_begin refactor, windows fixes

.github/workflows/build_linux.yml

@@ -16,7 +16,7 @@ jobs:
       uses: actions/checkout@v3
     - name: Install dependencies
       run: |
-        sudo apt-get install libx11-dev libxcursor-dev libxinerama-dev build-essential gettext libtool libtool-bin libpulse-dev libasound2-dev libjack-dev portaudio19-dev
+        sudo apt-get install libx11-dev libxcursor-dev libxinerama-dev build-essential gettext libtool libtool-bin libpulse-dev libasound2-dev libjack-dev portaudio19-dev libwayland-dev
     - name: Setup Vulkan
       uses: ./.github/actions/vulkan
     - name: Setup .NET
@@ -44,7 +44,7 @@ jobs:
       uses: actions/checkout@v3
     - name: Install dependencies
       run: |
-        sudo apt-get install libx11-dev libxcursor-dev libxinerama-dev
+        sudo apt-get install libx11-dev libxcursor-dev libxinerama-dev libwayland-dev
     - name: Setup Vulkan
       uses: ./.github/actions/vulkan
     - name: Setup .NET

.github/workflows/tests.yml

@@ -28,7 +28,7 @@ jobs:
         git lfs pull
     - name: Install dependencies
       run: |
-        sudo apt-get install libx11-dev libxcursor-dev libxinerama-dev build-essential gettext libtool libtool-bin libpulse-dev libasound2-dev libjack-dev portaudio19-dev
+        sudo apt-get install libx11-dev libxcursor-dev libxinerama-dev build-essential gettext libtool libtool-bin libpulse-dev libasound2-dev libjack-dev portaudio19-dev libwayland-dev
     - name: Build
       run: |
         ./GenerateProjectFiles.sh -vs2022 -log -verbose -printSDKs -dotnet=8

.lfsconfig

@@ -1,4 +1,4 @@
 # Redirect to our own Git LFS server
 [lfs]
-url="https://gitlab.flaxengine.com/flax/flaxengine.git/info/lfs"
+#url="https://gitlab.flaxengine.com/flax/flaxengine.git/info/lfs"
 locksverify = false

Flax.flaxproj

@@ -13,6 +13,7 @@
   "Configuration": {
     "UseCSharp": true,
     "UseLargeWorlds": false,
-    "UseDotNet": true
+    "UseDotNet": true,
+    "UseSDL": true
   }
 }

Source/Editor/GUI/ContextMenu/ContextMenuBase.cs

@@ -1,7 +1,10 @@
-#if PLATFORM_WINDOWS
+#if PLATFORM_WINDOWS || PLATFORM_SDL
 #define USE_IS_FOREGROUND
 #else
 #endif
+#if PLATFORM_SDL
+#define USE_SDL_WORKAROUNDS
+#endif
 // Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
 
 using System.Collections.Generic;
@@ -111,7 +114,7 @@ namespace FlaxEditor.GUI.ContextMenu
         }
 
         /// <summary>
-        /// Shows the empty menu popup o na screen.
+        /// Shows the empty menu popup on a screen.
         /// </summary>
         /// <param name="control">The target control.</param>
         /// <param name="area">The target control area to cover.</param>
@@ -203,6 +206,7 @@ namespace FlaxEditor.GUI.ContextMenu
             // Create window
             var desc = CreateWindowSettings.Default;
             desc.Position = locationSS;
+            //Editor.Log($"contextmenu loc: {locationSS}, in parentloc: {location}");
             desc.StartPosition = WindowStartPosition.Manual;
             desc.Size = dpiSize;
             desc.Fullscreen = false;
@@ -215,21 +219,27 @@ namespace FlaxEditor.GUI.ContextMenu
             desc.AllowMaximize = false;
             desc.AllowDragAndDrop = false;
             desc.IsTopmost = true;
-            desc.IsRegularWindow = false;
+            desc.Type = WindowType.Popup;
+            desc.Parent = parentWin.Window;
+            desc.Title = "ContextMenu";
             desc.HasSizingFrame = false;
             OnWindowCreating(ref desc);
             _window = Platform.CreateWindow(ref desc);
             _window.GotFocus += OnWindowGotFocus;
             _window.LostFocus += OnWindowLostFocus;
 
+#if USE_IS_FOREGROUND && USE_SDL_WORKAROUNDS
+            // The focus between popup and parent windows doesn't change, force hide the popup when clicked on parent
+            parentWin.Window.MouseDown += OnWindowMouseDown;
+            _window.Closed += () => parentWin.Window.MouseDown -= OnWindowMouseDown;
+#endif
+
             // Attach to the window
             _parentCM = parent as ContextMenuBase;
             Parent = _window.GUI;
 
             // Show
             Visible = true;
-            if (_window == null)
-                return;
             _window.Show();
             PerformLayout();
             _previouslyFocused = parentWin.FocusedControl;
@@ -378,6 +388,17 @@ namespace FlaxEditor.GUI.ContextMenu
             }
         }
 
+#if USE_SDL_WORKAROUNDS
+        private void OnWindowGotFocus()
+        {
+        }
+        
+        private void OnWindowMouseDown(ref Float2 mousePosition, MouseButton button, ref bool handled)
+        {
+            // The user clicked outside the popup window
+            Hide();
+        }
+#else
         private void OnWindowGotFocus()
         {
             var child = _childCM;
@@ -391,6 +412,7 @@ namespace FlaxEditor.GUI.ContextMenu
                 });
             }
         }
+#endif
 
         private void OnWindowLostFocus()
         {
@@ -489,7 +511,12 @@ namespace FlaxEditor.GUI.ContextMenu
             // Let root context menu to check if none of the popup windows
             if (_parentCM == null && !IsForeground)
             {
+#if USE_SDL_WORKAROUNDS
+                if (!IsMouseOver)
+                    Hide();
+#else
                 Hide();
+#endif
             }
         }
 #endif

Source/Editor/GUI/Docking/DockHintWindow.cs

@@ -67,9 +67,7 @@ namespace FlaxEditor.GUI.Docking
             Proxy.Window.MouseUp += OnMouseUp;
             Proxy.Window.MouseMove += OnMouseMove;
             Proxy.Window.LostFocus += OnLostFocus;
-
-            // Start tracking mouse
-            Proxy.Window.StartTrackingMouse(false);
+            _toMove.Window.Window.MouseUp += OnMouseUp; // Intercept the drag release mouse event from source window
 
             // Update window GUI
             Proxy.Window.GUI.PerformLayout();
@@ -77,13 +75,16 @@ namespace FlaxEditor.GUI.Docking
             // Update rectangles
             UpdateRects();
 
-            // Hide base window
-            window.Hide();
-
             // Enable hit window presentation
             Proxy.Window.RenderingEnabled = true;
             Proxy.Window.Show();
             Proxy.Window.Focus();
+            
+            // Hide base window
+            window.Hide();
+            
+            // Start tracking mouse
+            Proxy.Window.StartTrackingMouse(false);
         }
 
         /// <summary>
@@ -101,6 +102,8 @@ namespace FlaxEditor.GUI.Docking
             Proxy.Window.MouseUp -= OnMouseUp;
             Proxy.Window.MouseMove -= OnMouseMove;
             Proxy.Window.LostFocus -= OnLostFocus;
+            if (_toMove?.Window?.Window)
+                _toMove.Window.Window.MouseUp -= OnMouseUp;
 
             // Hide the proxy
             Proxy.Hide();
@@ -240,6 +243,8 @@ namespace FlaxEditor.GUI.Docking
         {
             var baseWinPos = _toMove.Window.Window.Position;
             _dragOffset = mouseScreenPosition - baseWinPos;
+
+            Editor.Log($"_dragOffset: {_dragOffset}, mouse: {mouseScreenPosition}, basewinpos: {baseWinPos}");
         }
 
         private void UpdateRects()
@@ -438,7 +443,7 @@ namespace FlaxEditor.GUI.Docking
                     settings.AllowMinimize = false;
                     settings.HasBorder = false;
                     settings.HasSizingFrame = false;
-                    settings.IsRegularWindow = false;
+                    settings.Type = WindowType.Utility;
                     settings.SupportsTransparency = true;
                     settings.ShowInTaskbar = false;
                     settings.ShowAfterFirstPaint = false;
@@ -470,7 +475,7 @@ namespace FlaxEditor.GUI.Docking
                 settings.AllowMinimize = false;
                 settings.HasBorder = false;
                 settings.HasSizingFrame = false;
-                settings.IsRegularWindow = false;
+                settings.Type = WindowType.Utility;
                 settings.SupportsTransparency = true;
                 settings.ShowInTaskbar = false;
                 settings.ActivateWhenFirstShown = false;

Source/Editor/GUI/Docking/FloatWindowDockPanel.cs

@@ -82,7 +82,7 @@ namespace FlaxEditor.GUI.Docking
             settings.AllowMaximize = true;
             settings.AllowDragAndDrop = true;
             settings.IsTopmost = false;
-            settings.IsRegularWindow = true;
+            settings.Type = WindowType.Regular;
             settings.HasSizingFrame = true;
             settings.ShowAfterFirstPaint = false;
             settings.ShowInTaskbar = true;

Source/Editor/GUI/Input/ValueBox.cs

@@ -266,6 +266,7 @@ namespace FlaxEditor.GUI.Input
             return base.OnMouseDown(location, button);
         }
 
+#if !PLATFORM_SDL
         /// <inheritdoc />
         public override void OnMouseMove(Float2 location)
         {
@@ -292,6 +293,36 @@ namespace FlaxEditor.GUI.Input
             base.OnMouseMove(location);
         }
 
+#else
+
+        /// <inheritdoc />
+        public override void OnMouseMoveRelative(Float2 mouseMotion)
+        {
+            var location = Root.TrackingMouseOffset;
+            if (_isSliding)
+            {
+                // Update sliding
+                ApplySliding(Root.TrackingMouseOffset.X * _slideSpeed);
+                return;
+            }
+
+            // Update cursor type so user knows they can slide value
+            if (CanUseSliding && SlideRect.Contains(location) && !_isSliding)
+            {
+                Cursor = CursorType.SizeWE;
+                _cursorChanged = true;
+            }
+            else if (_cursorChanged && !_isSliding)
+            {
+                Cursor = CursorType.Default;
+                _cursorChanged = false;
+            }
+
+            base.OnMouseMoveRelative(mouseMotion);
+        }
+
+#endif
+
         /// <inheritdoc />
         public override bool OnMouseUp(Float2 location, MouseButton button)
         {

Source/Editor/GUI/MainMenu.cs

@@ -12,7 +12,7 @@ namespace FlaxEditor.GUI
     /// <seealso cref="FlaxEngine.GUI.ContainerControl" />
     public sealed class MainMenu : ContainerControl
     {
-#if PLATFORM_WINDOWS
+#if PLATFORM_WINDOWS || PLATFORM_SDL
         private bool _useCustomWindowSystem;
         private Image _icon;
         private Label _title;
@@ -67,7 +67,7 @@ namespace FlaxEditor.GUI
             AutoFocus = false;
             AnchorPreset = AnchorPresets.HorizontalStretchTop;
 
-#if PLATFORM_WINDOWS
+#if PLATFORM_WINDOWS || PLATFORM_SDL
             _useCustomWindowSystem = !Editor.Instance.Options.Options.Interface.UseNativeWindowSystem;
             if (_useCustomWindowSystem)
             {
@@ -166,7 +166,7 @@ namespace FlaxEditor.GUI
             }
         }
 
-#if PLATFORM_WINDOWS
+#if PLATFORM_WINDOWS || PLATFORM_SDL
         /// <inheritdoc />
         public override void Update(float deltaTime)
         {
@@ -291,7 +291,7 @@ namespace FlaxEditor.GUI
             if (base.OnMouseDoubleClick(location, button))
                 return true;
 
-#if PLATFORM_WINDOWS
+#if PLATFORM_WINDOWS || PLATFORM_SDL
             var child = GetChildAtRecursive(location);
             if (_useCustomWindowSystem && child is not Button && child is not MainMenuButton)
             {
@@ -321,7 +321,7 @@ namespace FlaxEditor.GUI
         {
             float x = 0;
 
-#if PLATFORM_WINDOWS
+#if PLATFORM_WINDOWS || PLATFORM_SDL
             if (_useCustomWindowSystem)
             {
                 // Icon
@@ -349,7 +349,7 @@ namespace FlaxEditor.GUI
                 }
             }
 
-#if PLATFORM_WINDOWS
+#if PLATFORM_WINDOWS || PLATFORM_SDL
             if (_useCustomWindowSystem)
             {
                 // Buttons
@@ -367,7 +367,7 @@ namespace FlaxEditor.GUI
 #endif
         }
 
-#if PLATFORM_WINDOWS
+#if PLATFORM_WINDOWS || PLATFORM_SDL
         /// <inheritdoc />
         public override void OnDestroy()
         {

Source/Editor/GUI/MainMenuButton.cs

@@ -42,7 +42,7 @@ namespace FlaxEditor.GUI
             Text = text;
 
             var style = Style.Current;
-#if PLATFORM_WINDOWS
+#if PLATFORM_WINDOWS || PLATFORM_SDL
             if (Editor.Instance.Options.Options.Interface.UseNativeWindowSystem)
             {
                 BackgroundColorMouseOver = style.BackgroundHighlighted;

Source/Editor/Managed/ManagedEditor.Internal.cpp

@@ -435,6 +435,9 @@ DEFINE_INTERNAL_CALL(void) EditorInternal_RunVisualScriptBreakpointLoopTick(floa
             case InputDevice::EventType::MouseMove:
                 window->OnMouseMove(window->ScreenToClient(e.MouseData.Position));
                 break;
+            case InputDevice::EventType::MouseMoveRelative:
+                window->OnMouseMoveRelative(e.MouseMovementData.PositionRelative);
+                break;
             case InputDevice::EventType::MouseLeave:
                 window->OnMouseLeave();
                 break;

Source/Editor/Modules/UIModule.cs

@@ -381,7 +381,7 @@ namespace FlaxEditor.Modules
             Editor.Options.OptionsChanged += OnOptionsChanged;
 
             // Add dummy control for drawing the main window borders if using a custom style
-#if PLATFORM_WINDOWS
+#if PLATFORM_WINDOWS || PLATFORM_SDL
             if (!Editor.Options.Options.Interface.UseNativeWindowSystem)
 #endif
             {

Source/Editor/Modules/WindowsModule.cs

@@ -760,8 +760,10 @@ namespace FlaxEditor.Modules
             {
                 settings.HasBorder = false;
 
+#if !PLATFORM_SDL
                 // Skip OS sizing frame and implement it using LeftButtonHit
                 settings.HasSizingFrame = false;
+#endif
             }
 #elif PLATFORM_LINUX
             settings.HasBorder = false;

Source/Editor/Options/InterfaceOptions.cs

@@ -167,7 +167,7 @@ namespace FlaxEditor.Options
         [EditorDisplay("Interface"), EditorOrder(10), Tooltip("Editor User Interface scale. Applied to all UI elements, windows and text. Can be used to scale the interface up on a bigger display. Editor restart required.")]
         public float InterfaceScale { get; set; } = 1.0f;
 
-#if PLATFORM_WINDOWS
+#if PLATFORM_WINDOWS || PLATFORM_SDL
         /// <summary>
         /// Gets or sets a value indicating whether use native window title bar. Editor restart required.
         /// </summary>

Source/Editor/Utilities/ScreenUtilities.cpp

@@ -1,131 +0,0 @@
-// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
-
-#include "ScreenUtilities.h"
-#include "Engine/Core/Math/Vector2.h"
-#include "Engine/Core/Delegate.h"
-#include "Engine/Core/Log.h"
-#include "Engine/Profiler/ProfilerCPU.h"
-
-Delegate<Color32> ScreenUtilities::PickColorDone;
-
-#if PLATFORM_WINDOWS
-
-#include <Windows.h>
-
-#pragma comment(lib, "Gdi32.lib")
-
-static HHOOK MouseCallbackHook;
-
-LRESULT CALLBACK OnScreenUtilsMouseCallback(_In_ int nCode, _In_ WPARAM wParam, _In_ LPARAM lParam)
-{
-    if (nCode >= 0 && wParam == WM_LBUTTONDOWN)
-    {
-        UnhookWindowsHookEx(MouseCallbackHook);
-
-        // Push event with the picked color
-        const Float2 cursorPos = Platform::GetMousePosition();
-        const Color32 colorPicked = ScreenUtilities::GetColorAt(cursorPos);
-        ScreenUtilities::PickColorDone(colorPicked);
-        return 1;
-    }
-    return CallNextHookEx(NULL, nCode, wParam, lParam);
-}
-
-Color32 ScreenUtilities::GetColorAt(const Float2& pos)
-{
-    PROFILE_CPU();
-    HDC deviceContext = GetDC(NULL);
-    COLORREF color = GetPixel(deviceContext, (int)pos.X, (int)pos.Y);
-    ReleaseDC(NULL, deviceContext);
-    return Color32(GetRValue(color), GetGValue(color), GetBValue(color), 255);
-}
-
-void ScreenUtilities::PickColor()
-{
-    MouseCallbackHook = SetWindowsHookEx(WH_MOUSE_LL, OnScreenUtilsMouseCallback, NULL, NULL);
-    if (MouseCallbackHook == NULL)
-    {
-        LOG(Warning, "Failed to set mouse hook.");
-        LOG(Warning, "Error: {0}", GetLastError());
-    }
-}
-
-#elif PLATFORM_LINUX
-
-#include "Engine/Platform/Linux/LinuxPlatform.h"
-#include "Engine/Platform/Linux/IncludeX11.h"
-
-Color32 ScreenUtilities::GetColorAt(const Float2& pos)
-{
-    X11::XColor color;
-    
-    X11::Display* display = (X11::Display*) LinuxPlatform::GetXDisplay();
-    int defaultScreen = X11::XDefaultScreen(display);
-
-    X11::XImage* image;
-    image = X11::XGetImage(display, X11::XRootWindow(display, defaultScreen), (int)pos.X, (int)pos.Y, 1, 1, AllPlanes, XYPixmap);
-    color.pixel = XGetPixel(image, 0, 0);
-    X11::XFree(image);
-
-    X11::XQueryColor(display, X11::XDefaultColormap(display, defaultScreen), &color);
-
-    Color32 outputColor;
-    outputColor.R = color.red / 256;
-    outputColor.G = color.green / 256;
-    outputColor.B = color.blue / 256;
-    outputColor.A = 255;
-    return outputColor;
-}
-
-void OnScreenUtilsXEventCallback(void* eventPtr)
-{
-    X11::XEvent* event = (X11::XEvent*) eventPtr;
-    X11::Display* display = (X11::Display*)LinuxPlatform::GetXDisplay();
-    if (event->type == ButtonPress)
-    {
-        const Float2 cursorPos = Platform::GetMousePosition();
-        const Color32 colorPicked = ScreenUtilities::GetColorAt(cursorPos);
-        X11::XUngrabPointer(display, CurrentTime);
-        ScreenUtilities::PickColorDone(colorPicked);
-        LinuxPlatform::xEventRecieved.Unbind(OnScreenUtilsXEventCallback);
-    }
-}
-
-void ScreenUtilities::PickColor()
-{
-    PROFILE_CPU();
-    X11::Display* display = (X11::Display*) LinuxPlatform::GetXDisplay();
-    X11::Window rootWindow = X11::XRootWindow(display, X11::XDefaultScreen(display));
-
-    X11::Cursor cursor = XCreateFontCursor(display, 130);
-    int grabbedPointer = X11::XGrabPointer(display, rootWindow, 0,  ButtonPressMask, GrabModeAsync, GrabModeAsync, rootWindow, cursor, CurrentTime);
-    if (grabbedPointer != GrabSuccess)
-    {
-        LOG(Error, "Failed to grab cursor for events.");
-        X11::XFreeCursor(display, cursor);
-        return;
-    }
-
-    X11::XFreeCursor(display, cursor);
-    LinuxPlatform::xEventRecieved.Bind(OnScreenUtilsXEventCallback);
-}
-
-#elif PLATFORM_MAC
-
-#include <Cocoa/Cocoa.h>
-#include <AppKit/AppKit.h>
-
-Color32 ScreenUtilities::GetColorAt(const Float2& pos)
-{
-    // TODO: implement ScreenUtilities for macOS
-    return { 0, 0, 0, 255 };
-}
-
-void ScreenUtilities::PickColor()
-{
-    // This is what C# calls to start the color picking sequence
-    // This should stop mouse clicks from working for one click, and that click is on the selected color
-    // There is a class called NSColorSample that might implement that for you, but maybe not.
-}
-
-#endif

Source/Editor/Utilities/ScreenUtilities.h

@@ -2,32 +2,4 @@
 
 #pragma once
 
-#include "Engine/Core/Types/BaseTypes.h"
-#include "Engine/Core/Math/Color32.h"
-#include "Engine/Core/Math/Vector2.h"
-#include "Engine/Core/Delegate.h"
-
-/// <summary>
-/// Platform-dependent screen utilities.
-/// </summary>
-API_CLASS(Static) class FLAXENGINE_API ScreenUtilities
-{
-    DECLARE_SCRIPTING_TYPE_MINIMAL(ScreenUtilities);
-
-    /// <summary>
-    /// Gets the pixel color at the specified coordinates.
-    /// </summary>
-    /// <param name="pos">Screen-space coordinate to read.</param>
-    /// <returns>Pixel color at the specified coordinates.</returns>
-    API_FUNCTION() static Color32 GetColorAt(const Float2& pos);
-
-    /// <summary>
-    /// Starts async color picking. Color will be returned through PickColorDone event when the actions ends (user selected the final color with a mouse). When action is active, GetColorAt can be used to read the current value.
-    /// </summary>
-    API_FUNCTION() static void PickColor();
-
-    /// <summary>
-    /// Called when PickColor action is finished.
-    /// </summary>
-    API_EVENT() static Delegate<Color32> PickColorDone;
-};
+#include "Engine/Platform/ScreenUtilities.h"

Source/Editor/Viewport/EditorGizmoViewport.cs

@@ -77,7 +77,7 @@ namespace FlaxEditor.Viewport
         public bool SnapToVertex => ContainsFocus && Editor.Instance.Options.Options.Input.SnapToVertex.Process(Root);
 
         /// <inheritdoc />
-        public Float2 MouseDelta => _mouseDelta;
+        public Float2 MouseDelta => FlaxEngine.Input.MousePositionDelta;
 
         /// <inheritdoc />
         public bool UseSnapping => Root?.GetKey(KeyboardKeys.Control) ?? false;

Source/Editor/Viewport/EditorViewport.cs

@@ -158,18 +158,22 @@ namespace FlaxEditor.Viewport
         private float _movementSpeed;
         private float _minMovementSpeed;
         private float _maxMovementSpeed;
+#if !PLATFORM_SDL
         private float _mouseAccelerationScale;
         private bool _useMouseFiltering;
         private bool _useMouseAcceleration;
+#endif
 
         // Input
 
         internal bool _disableInputUpdate;
         private bool _isControllingMouse, _isViewportControllingMouse, _wasVirtualMouseRightDown, _isVirtualMouseRightDown;
-        private int _deltaFilteringStep;
         private Float2 _startPos;
+#if !PLATFORM_SDL
         private Float2 _mouseDeltaLast;
+        private int _deltaFilteringStep;
         private Float2[] _deltaFilteringBuffer = new Float2[FpsCameraFilteringFrames];
+#endif
 
         /// <summary>
         /// The previous input (from the previous update).
@@ -525,10 +529,11 @@ namespace FlaxEditor.Viewport
         : base(task)
         {
             _editor = Editor.Instance;
-
+#if !PLATFORM_SDL
             _mouseAccelerationScale = 0.1f;
             _useMouseFiltering = false;
             _useMouseAcceleration = false;
+#endif
             _camera = camera;
             if (_camera != null)
                 _camera.Viewport = this;
@@ -1456,7 +1461,9 @@ namespace FlaxEditor.Viewport
             // Hide cursor and start tracking mouse movement
             win.StartTrackingMouse(false);
             win.Cursor = CursorType.Hidden;
+            win.MouseMoveRelative += OnMouseMoveRelative;
 
+#if !PLATFORM_SDL
             // Center mouse position if it's too close to the edge
             var size = Size;
             var center = Float2.Round(size * 0.5f);
@@ -1465,6 +1472,7 @@ namespace FlaxEditor.Viewport
                 _viewMousePos = center;
                 win.MousePosition = PointToWindow(_viewMousePos);
             }
+#endif
         }
 
         /// <summary>
@@ -1476,6 +1484,7 @@ namespace FlaxEditor.Viewport
             // Restore cursor and stop tracking mouse movement
             win.Cursor = CursorType.Default;
             win.EndTrackingMouse();
+            win.MouseMoveRelative -= OnMouseMoveRelative;
         }
 
         /// <summary>
@@ -1580,6 +1589,14 @@ namespace FlaxEditor.Viewport
                     else
                         EndMouseCapture();
                 }
+#if PLATFORM_SDL
+                bool useMouse = IsControllingMouse || true;
+                _prevInput = _input;
+                if (canUseInput && ContainsFocus)
+                    _input.Gather(win.Window, useMouse, ref _prevInput);
+                else
+                    _input.Clear();
+#else
                 bool useMouse = IsControllingMouse || (Mathf.IsInRange(_viewMousePos.X, 0, Width) && Mathf.IsInRange(_viewMousePos.Y, 0, Height));
                 _prevInput = _input;
                 var hit = GetChildAt(_viewMousePos, c => c.Visible && !(c is CanvasRootControl) && !(c is UIEditorRoot));
@@ -1587,6 +1604,7 @@ namespace FlaxEditor.Viewport
                     _input.Gather(win.Window, useMouse, ref _prevInput);
                 else
                     _input.Clear();
+#endif
 
                 // Track controlling mouse state change
                 bool wasControllingMouse = _prevInput.IsControllingMouse;
@@ -1695,6 +1713,10 @@ namespace FlaxEditor.Viewport
                 if (_input.IsControlDown)
                     moveDelta *= 0.3f;
 
+#if PLATFORM_SDL
+                var mouseDelta = _mouseDelta;
+                _mouseDelta = Float2.Zero;
+#else
                 // Calculate smooth mouse delta not dependant on viewport size
                 var offset = _viewMousePos - _startPos;
                 if (_input.IsZooming && !_input.IsMouseRightDown && !_input.IsMouseLeftDown && !_input.IsMouseMiddleDown && !_isOrtho && !rmbWheel && !_isVirtualMouseRightDown)
@@ -1736,6 +1758,7 @@ namespace FlaxEditor.Viewport
                     mouseDelta += _mouseDeltaLast * _mouseAccelerationScale;
                     _mouseDeltaLast = currentDelta;
                 }
+#endif
 
                 // Update
                 moveDelta *= dt * (60.0f * 4.0f);
@@ -1744,12 +1767,14 @@ namespace FlaxEditor.Viewport
                     mouseDelta *= new Float2(1, -1);
                 UpdateView(dt, ref moveDelta, ref mouseDelta, out var centerMouse);
 
+#if !PLATFORM_SDL
                 // Move mouse back to the root position
                 if (centerMouse && (_input.IsMouseRightDown || _input.IsMouseLeftDown || _input.IsMouseMiddleDown || _isVirtualMouseRightDown))
                 {
                     var center = PointToWindow(_startPos);
                     win.MousePosition = center;
                 }
+#endif
 
                 // Change Ortho size on mouse scroll
                 if (_isOrtho && !rmbWheel)
@@ -1761,6 +1786,8 @@ namespace FlaxEditor.Viewport
             }
             else
             {
+#if PLATFORM_SDL
+#else
                 if (_input.IsMouseLeftDown || _input.IsMouseRightDown || _isVirtualMouseRightDown)
                 {
                     // Calculate smooth mouse delta not dependant on viewport size
@@ -1775,6 +1802,7 @@ namespace FlaxEditor.Viewport
                     _mouseDelta = Float2.Zero;
                 }
                 _mouseDeltaLast = Float2.Zero;
+#endif
 
                 if (ContainsFocus)
                 {
@@ -1824,6 +1852,12 @@ namespace FlaxEditor.Viewport
             _input.MouseWheelDelta = 0;
         }
 
+        /// <inheritdoc />
+        public void OnMouseMoveRelative(ref Float2 mouseMotion)
+        {
+            _mouseDelta += mouseMotion;
+        }
+
         /// <inheritdoc />
         public override bool OnMouseDown(Float2 location, MouseButton button)
         {

Source/Editor/Windows/GameWindow.cs

@@ -1068,8 +1068,11 @@ namespace FlaxEditor.Windows
 
             if (Editor.StateMachine.IsPlayMode && !Editor.StateMachine.PlayingState.IsPaused)
             {
+                // Make sure the cursor is always in the viewport when cursor is locked
+                bool forceCenter = _cursorLockMode != CursorLockMode.None && !IsMouseOver;
+
                 // Center mouse in play mode
-                if (CenterMouseOnFocus)
+                if (CenterMouseOnFocus || forceCenter)
                 {
                     var center = PointToWindow(Size * 0.5f);
                     Root.MousePosition = center;

Source/Editor/Windows/Profiler/CPU.cs

@@ -175,7 +175,7 @@ namespace FlaxEditor.Windows.Profiler
 
         private string FormatCellBytes(object x)
         {
-            return Utilities.Utils.FormatBytesCount((ulong)x);
+            return Utilities.Utils.FormatBytesCount((ulong)(int)x);
         }
 
         /// <inheritdoc />

Source/Editor/Windows/SplashScreen.cpp

@@ -28,7 +28,7 @@ const Char* SplashScreenQuotes[] =
 #elif PLATFORM_LINUX
     TEXT("Try it on a Raspberry"),
     TEXT("Trying to exit vim"),
-    TEXT("Sudo flax --loadproject"),
+    TEXT("sudo flax --project HelloWorld.flaxproj"),
 #elif PLATFORM_MAC
     TEXT("don't compare Macbooks to oranges."),
     TEXT("Why does macbook heat up?\nBecause it doesn't have windows"),
@@ -104,6 +104,7 @@ const Char* SplashScreenQuotes[] =
     TEXT("You have my bow.\nAnd my axe!"),
     TEXT("To the bridge of Khazad-dum."),
     TEXT("One ring to rule them all.\nOne ring to find them."),
+    TEXT("Where there's a whip, there's a way."),
     TEXT("That's what she said"),
     TEXT("We could be compiling shaders here"),
     TEXT("Hello There"),
@@ -164,7 +165,7 @@ void SplashScreen::Show()
     settings.AllowMaximize = false;
     settings.AllowDragAndDrop = false;
     settings.IsTopmost = false;
-    settings.IsRegularWindow = false;
+    settings.Type = WindowType::Utility;
     settings.HasSizingFrame = false;
     settings.ShowAfterFirstPaint = true;
     settings.StartPosition = WindowStartPosition::CenterScreen;

Source/Engine/Engine/CommandLine.cpp

@@ -145,6 +145,12 @@ bool CommandLine::Parse(const Char* cmdLine)
     PARSE_BOOL_SWITCH("-monolog ", MonoLog);
     PARSE_BOOL_SWITCH("-mute ", Mute);
     PARSE_BOOL_SWITCH("-lowdpi ", LowDPI);
+
+#if PLATFORM_LINUX && PLATFORM_SDL
+    PARSE_BOOL_SWITCH("-wayland ", Wayland);
+    PARSE_BOOL_SWITCH("-x11 ", X11);
+#endif
+
 #if USE_EDITOR
     PARSE_BOOL_SWITCH("-clearcache ", ClearCache);
     PARSE_BOOL_SWITCH("-clearcooker ", ClearCookerCache);

Source/Engine/Engine/CommandLine.h

@@ -127,6 +127,20 @@ public:
         /// </summary>
         Nullable<bool> LowDPI;
 
+#if PLATFORM_LINUX && PLATFORM_SDL
+
+        /// <summary>
+        /// -wayland (prefer Wayland over X11 as display server)
+        /// </summary>
+        Nullable<bool> Wayland;
+
+        /// <summary>
+        /// -x11 (prefer X11 over Wayland as display server)
+        /// </summary>
+        Nullable<bool> X11;
+
+#endif
+
 #if USE_EDITOR
         /// <summary>
         /// -project !path! (Startup project path)

Source/Engine/Engine/Engine.cpp

@@ -95,13 +95,14 @@ int32 Engine::Main(const Char* cmdLine)
     CommandLine::Options.Std = true;
 #endif
 
+    Platform::SetHighDpiAwarenessEnabled(!CommandLine::Options.LowDPI.IsTrue());
+
     if (Platform::Init())
     {
         Platform::Fatal(TEXT("Cannot init platform."));
         return -1;
     }
 
-    Platform::SetHighDpiAwarenessEnabled(!CommandLine::Options.LowDPI.IsTrue());
     Time::StartupTime = DateTime::Now();
     Globals::StartupFolder = Globals::BinariesFolder = Platform::GetMainDirectory();
 #if USE_EDITOR

Source/Engine/Engine/Screen.cpp

@@ -6,6 +6,8 @@
 #include "Engine/Core/Types/Nullable.h"
 #include "Engine/Platform/Window.h"
 #include "Engine/Engine/EngineService.h"
+#include "Engine/Input/Input.h"
+#include "Engine/Input/Mouse.h"
 #if USE_EDITOR
 #include "Editor/Editor.h"
 #include "Editor/Managed/ManagedEditor.h"
@@ -13,10 +15,14 @@
 #include "Engine/Engine/Engine.h"
 #endif
 
-Nullable<bool> Fullscreen;
-Nullable<Float2> Size;
-bool CursorVisible = true;
-CursorLockMode CursorLock = CursorLockMode::None;
+namespace
+{
+    Nullable<bool> Fullscreen;
+    Nullable<Float2> Size;
+    bool CursorVisible = true;
+    CursorLockMode CursorLock = CursorLockMode::None;
+    bool LastGameViewportFocus = false;
+}
 
 class ScreenService : public EngineService
 {
@@ -100,11 +106,25 @@ void Screen::SetCursorVisible(const bool value)
 #else
 	const auto win = Engine::MainWindow;
 #endif
+    bool focused = false;
     if (win && Engine::HasGameViewportFocus())
     {
         win->SetCursor(value ? CursorType::Default : CursorType::Hidden);
+        focused = true;
     }
+    else if (win)
+        win->SetCursor(CursorType::Default);
     CursorVisible = value;
+
+    // Just enable relative mode when cursor is constrained and not visible
+    if (CursorLock != CursorLockMode::None && !CursorVisible && focused)
+    {
+        Input::Mouse->SetRelativeMode(true, win);
+    }
+    else if (CursorLock == CursorLockMode::None || CursorVisible || !focused)
+    {
+        Input::Mouse->SetRelativeMode(false, win);
+    }
 }
 
 CursorLockMode Screen::GetCursorLock()
@@ -133,6 +153,17 @@ void Screen::SetCursorLock(CursorLockMode mode)
         win->EndClippingCursor();
     }
     CursorLock = mode;
+
+    // Just enable relative mode when cursor is constrained and not visible
+    bool focused = win && Engine::HasGameViewportFocus();
+    if (CursorLock != CursorLockMode::None && !CursorVisible && focused)
+    {
+        Input::Mouse->SetRelativeMode(true, win);
+    }
+    else if (CursorLock == CursorLockMode::None || CursorVisible || !focused)
+    {
+        Input::Mouse->SetRelativeMode(false, win);
+    }
 }
 
 GameWindowMode Screen::GetGameWindowMode()
@@ -190,7 +221,11 @@ void ScreenService::Update()
 {
 #if USE_EDITOR
     // Sync current cursor state in Editor (eg. when viewport focus can change)
-    Screen::SetCursorVisible(CursorVisible);
+    const auto win = Editor::Managed->GetGameWindow(true);
+    bool gameViewportFocus = win && Engine::HasGameViewportFocus();
+    if (gameViewportFocus != LastGameViewportFocus)
+        Screen::SetCursorVisible(CursorVisible);
+    LastGameViewportFocus = gameViewportFocus;
 #endif
 }
 

Source/Engine/GraphicsDevice/Vulkan/Android/AndroidVulkanPlatform.cpp

@@ -4,6 +4,7 @@
 
 #include "AndroidVulkanPlatform.h"
 #include "../RenderToolsVulkan.h"
+#include "Engine/Platform/Window.h"
 
 void AndroidVulkanPlatform::GetInstanceExtensions(Array<const char*>& extensions, Array<const char*>& layers)
 {
@@ -17,8 +18,10 @@ void AndroidVulkanPlatform::GetDeviceExtensions(Array<const char*>& extensions,
 	extensions.Add(VK_KHR_ANDROID_SURFACE_EXTENSION_NAME);
 }
 
-void AndroidVulkanPlatform::CreateSurface(void* windowHandle, VkInstance instance, VkSurfaceKHR* surface)
+void AndroidVulkanPlatform::CreateSurface(Window* window, VkInstance instance, VkSurfaceKHR* surface)
 {
+    ASSERT(window);
+    void* windowHandle = window->GetNativePtr();
     ASSERT(windowHandle);
     VkAndroidSurfaceCreateInfoKHR surfaceCreateInfo;
     RenderToolsVulkan::ZeroStruct(surfaceCreateInfo, VK_STRUCTURE_TYPE_ANDROID_SURFACE_CREATE_INFO_KHR);

Source/Engine/GraphicsDevice/Vulkan/Android/AndroidVulkanPlatform.h

@@ -17,7 +17,7 @@ class AndroidVulkanPlatform : public VulkanPlatformBase
 public:
 	static void GetInstanceExtensions(Array<const char*>& extensions, Array<const char*>& layers);
 	static void GetDeviceExtensions(Array<const char*>& extensions, Array<const char*>& layers);
-	static void CreateSurface(void* windowHandle, VkInstance instance, VkSurfaceKHR* surface);
+	static void CreateSurface(Window* window, VkInstance instance, VkSurfaceKHR* surface);
 };
 
 typedef AndroidVulkanPlatform VulkanPlatform;

Source/Engine/GraphicsDevice/Vulkan/GPUSwapChainVulkan.cpp

@@ -192,7 +192,7 @@ bool GPUSwapChainVulkan::CreateSwapChain(int32 width, int32 height)
     ASSERT_LOW_LAYER(_backBuffers.Count() == 0);
 
     // Create platform-dependent surface
-    VulkanPlatform::CreateSurface(windowHandle, GPUDeviceVulkan::Instance, &_surface);
+    VulkanPlatform::CreateSurface(_window, GPUDeviceVulkan::Instance, &_surface);
     if (_surface == VK_NULL_HANDLE)
     {
         LOG(Warning, "Failed to create Vulkan surface.");

Source/Engine/GraphicsDevice/Vulkan/Linux/LinuxVulkanPlatform.cpp

@@ -4,62 +4,62 @@
 
 #include "LinuxVulkanPlatform.h"
 #include "../RenderToolsVulkan.h"
+#include "Engine/Platform/Window.h"
 
-// Contents of vulkan\vulkan_xlib.h inlined here to prevent typename collisions with engine types due to X11 types
 #include "Engine/Platform/Linux/IncludeX11.h"
-#ifdef __cplusplus
-extern "C" {
-#endif
-#define VK_KHR_xlib_surface 1
-#define VK_KHR_XLIB_SURFACE_SPEC_VERSION  6
-#define VK_KHR_XLIB_SURFACE_EXTENSION_NAME "VK_KHR_xlib_surface"
-typedef VkFlags VkXlibSurfaceCreateFlagsKHR;
+#define Display X11::Display
+#define Window X11::Window
+#define VisualID X11::VisualID
+#include "vulkan/vulkan_xlib.h"
+#undef Display
+#undef Window
+#undef VisualID
 
-typedef struct VkXlibSurfaceCreateInfoKHR
-{
-	VkStructureType sType;
-	const void* pNext;
-	VkXlibSurfaceCreateFlagsKHR flags;
-	X11::Display* dpy;
-	X11::Window window;
-} VkXlibSurfaceCreateInfoKHR;
+#include "vulkan/vulkan_wayland.h"
 
-typedef VkResult (VKAPI_PTR *PFN_vkCreateXlibSurfaceKHR)(VkInstance instance, const VkXlibSurfaceCreateInfoKHR* pCreateInfo, const VkAllocationCallbacks* pAllocator, VkSurfaceKHR* pSurface);
-typedef VkBool32 (VKAPI_PTR *PFN_vkGetPhysicalDeviceXlibPresentationSupportKHR)(VkPhysicalDevice physicalDevice, uint32_t queueFamilyIndex, X11::Display* dpy, X11::VisualID visualID);
-#ifndef VK_NO_PROTOTYPES
-VKAPI_ATTR VkResult VKAPI_CALL vkCreateXlibSurfaceKHR(
-    VkInstance                                  instance,
-    const VkXlibSurfaceCreateInfoKHR*           pCreateInfo,
-    const VkAllocationCallbacks*                pAllocator,
-    VkSurfaceKHR*                               pSurface);
-VKAPI_ATTR VkBool32 VKAPI_CALL vkGetPhysicalDeviceXlibPresentationSupportKHR(
-    VkPhysicalDevice                            physicalDevice,
-    uint32_t                                    queueFamilyIndex,
-    Display*                                    dpy,
-    VisualID                                    visualID);
-#endif
-#ifdef __cplusplus
-}
-#endif
-//
-
-// Export X11 surface extension from volk
+// Export extension from volk
 extern PFN_vkCreateXlibSurfaceKHR vkCreateXlibSurfaceKHR;
 extern PFN_vkGetPhysicalDeviceXlibPresentationSupportKHR vkGetPhysicalDeviceXlibPresentationSupportKHR;
+extern PFN_vkCreateWaylandSurfaceKHR vkCreateWaylandSurfaceKHR;
+extern PFN_vkGetPhysicalDeviceWaylandPresentationSupportKHR vkGetPhysicalDeviceWaylandPresentationSupportKHR;
 
 void LinuxVulkanPlatform::GetInstanceExtensions(Array<const char*>& extensions, Array<const char*>& layers)
 {
 	extensions.Add(VK_KHR_SURFACE_EXTENSION_NAME);
 	extensions.Add(VK_KHR_XLIB_SURFACE_EXTENSION_NAME);
+    extensions.Add(VK_KHR_WAYLAND_SURFACE_EXTENSION_NAME);
 }
 
-void LinuxVulkanPlatform::CreateSurface(void* windowHandle, VkInstance instance, VkSurfaceKHR* surface)
+void LinuxVulkanPlatform::CreateSurface(Window* window, VkInstance instance, VkSurfaceKHR* surface)
 {
+#if !PLATFORM_SDL
+    void* windowHandle = window->GetNativePtr();
 	VkXlibSurfaceCreateInfoKHR surfaceCreateInfo;
 	RenderToolsVulkan::ZeroStruct(surfaceCreateInfo, VK_STRUCTURE_TYPE_XLIB_SURFACE_CREATE_INFO_KHR);
-	surfaceCreateInfo.dpy = (X11::Display*)LinuxPlatform::GetXDisplay();
+	surfaceCreateInfo.dpy = (X11::Display*)Platform::GetXDisplay();
 	surfaceCreateInfo.window = (X11::Window)windowHandle;
 	VALIDATE_VULKAN_RESULT(vkCreateXlibSurfaceKHR(instance, &surfaceCreateInfo, nullptr, surface));
+#else
+    SDLWindow* sdlWindow = static_cast<Window*>(window);
+    X11::Window x11Window = (X11::Window)sdlWindow->GetX11WindowHandle();
+    wl_surface* waylandSurface = (wl_surface*)sdlWindow->GetWaylandSurfacePtr();
+    if (waylandSurface != nullptr)
+    {
+        VkWaylandSurfaceCreateInfoKHR surfaceCreateInfo;
+        RenderToolsVulkan::ZeroStruct(surfaceCreateInfo, VK_STRUCTURE_TYPE_WAYLAND_SURFACE_CREATE_INFO_KHR);
+        surfaceCreateInfo.display = (wl_display*)sdlWindow->GetWaylandDisplay();
+        surfaceCreateInfo.surface = waylandSurface;
+        VALIDATE_VULKAN_RESULT(vkCreateWaylandSurfaceKHR(instance, &surfaceCreateInfo, nullptr, surface));
+    }
+    else if (x11Window != 0)
+    {
+        VkXlibSurfaceCreateInfoKHR surfaceCreateInfo;
+        RenderToolsVulkan::ZeroStruct(surfaceCreateInfo, VK_STRUCTURE_TYPE_XLIB_SURFACE_CREATE_INFO_KHR);
+        surfaceCreateInfo.dpy = (X11::Display*)sdlWindow->GetX11Display();
+        surfaceCreateInfo.window = x11Window;
+        VALIDATE_VULKAN_RESULT(vkCreateXlibSurfaceKHR(instance, &surfaceCreateInfo, nullptr, surface));
+    }
+#endif
 }
 
 #endif

Source/Engine/GraphicsDevice/Vulkan/Linux/LinuxVulkanPlatform.h

@@ -19,7 +19,7 @@ class LinuxVulkanPlatform : public VulkanPlatformBase
 {
 public:
 	static void GetInstanceExtensions(Array<const char*>& extensions, Array<const char*>& layers);
-	static void CreateSurface(void* windowHandle, VkInstance instance, VkSurfaceKHR* outSurface);
+	static void CreateSurface(Window* window, VkInstance instance, VkSurfaceKHR* outSurface);
 };
 
 typedef LinuxVulkanPlatform VulkanPlatform;

Source/Engine/GraphicsDevice/Vulkan/Mac/MacVulkanPlatform.cpp

@@ -4,6 +4,7 @@
 
 #include "MacVulkanPlatform.h"
 #include "../RenderToolsVulkan.h"
+#include "Engine/Platform/Window.h"
 #include <Cocoa/Cocoa.h>
 
 void MacVulkanPlatform::GetInstanceExtensions(Array<const char*>& extensions, Array<const char*>& layers)
@@ -12,12 +13,13 @@ void MacVulkanPlatform::GetInstanceExtensions(Array<const char*>& extensions, Ar
 	extensions.Add(VK_MVK_MACOS_SURFACE_EXTENSION_NAME);
 }
 
-void MacVulkanPlatform::CreateSurface(void* windowHandle, VkInstance instance, VkSurfaceKHR* surface)
+void MacVulkanPlatform::CreateSurface(Window* window, VkInstance instance, VkSurfaceKHR* surface)
 {
-    NSWindow* window = (NSWindow*)windowHandle;
+    void* windowHandle = window->GetNativePtr();
+    NSWindow* nswindow = (NSWindow*)windowHandle;
 	VkMacOSSurfaceCreateInfoMVK surfaceCreateInfo;
 	RenderToolsVulkan::ZeroStruct(surfaceCreateInfo, VK_STRUCTURE_TYPE_MACOS_SURFACE_CREATE_INFO_MVK);
-	surfaceCreateInfo.pView = (void*)window.contentView;
+	surfaceCreateInfo.pView = (void*)nswindow.contentView;
 	VALIDATE_VULKAN_RESULT(vkCreateMacOSSurfaceMVK(instance, &surfaceCreateInfo, nullptr, surface));
 }
 

Source/Engine/GraphicsDevice/Vulkan/Mac/MacVulkanPlatform.h

@@ -18,7 +18,7 @@ class MacVulkanPlatform : public VulkanPlatformBase
 {
 public:
 	static void GetInstanceExtensions(Array<const char*>& extensions, Array<const char*>& layers);
-	static void CreateSurface(void* windowHandle, VkInstance instance, VkSurfaceKHR* outSurface);
+	static void CreateSurface(Window* window, VkInstance instance, VkSurfaceKHR* outSurface);
 };
 
 typedef MacVulkanPlatform VulkanPlatform;

Source/Engine/GraphicsDevice/Vulkan/Win32/Win32VulkanPlatform.cpp

@@ -6,6 +6,7 @@
 
 #include "../RenderToolsVulkan.h"
 #include "Engine/Graphics/GPUDevice.h"
+#include "Engine/Platform/Window.h"
 
 void Win32VulkanPlatform::GetInstanceExtensions(Array<const char*>& extensions, Array<const char*>& layers)
 {
@@ -13,8 +14,9 @@ void Win32VulkanPlatform::GetInstanceExtensions(Array<const char*>& extensions,
     extensions.Add(VK_KHR_WIN32_SURFACE_EXTENSION_NAME);
 }
 
-void Win32VulkanPlatform::CreateSurface(void* windowHandle, VkInstance instance, VkSurfaceKHR* surface)
+void Win32VulkanPlatform::CreateSurface(Window* window, VkInstance instance, VkSurfaceKHR* surface)
 {
+    void* windowHandle = window->GetNativePtr();
     VkWin32SurfaceCreateInfoKHR surfaceCreateInfo;
     RenderToolsVulkan::ZeroStruct(surfaceCreateInfo, VK_STRUCTURE_TYPE_WIN32_SURFACE_CREATE_INFO_KHR);
     surfaceCreateInfo.hinstance = GetModuleHandle(nullptr);

Source/Engine/GraphicsDevice/Vulkan/Win32/Win32VulkanPlatform.h

@@ -17,7 +17,7 @@ class Win32VulkanPlatform : public VulkanPlatformBase
 {
 public:
     static void GetInstanceExtensions(Array<const char*>& extensions, Array<const char*>& layers);
-    static void CreateSurface(void* windowHandle, VkInstance instance, VkSurfaceKHR* surface);
+    static void CreateSurface(Window* window, VkInstance instance, VkSurfaceKHR* surface);
 };
 
 typedef Win32VulkanPlatform VulkanPlatform;

Source/Engine/GraphicsDevice/Vulkan/iOS/iOSVulkanPlatform.cpp

@@ -5,6 +5,7 @@
 #include "iOSVulkanPlatform.h"
 #include "../RenderToolsVulkan.h"
 #include "Engine/Core/Delegate.h"
+#include "Engine/Platform/Window.h"
 #include <UIKit/UIKit.h>
 
 void iOSVulkanPlatform::GetInstanceExtensions(Array<const char*>& extensions, Array<const char*>& layers)
@@ -13,8 +14,9 @@ void iOSVulkanPlatform::GetInstanceExtensions(Array<const char*>& extensions, Ar
 	extensions.Add(VK_MVK_IOS_SURFACE_EXTENSION_NAME);
 }
 
-void iOSVulkanPlatform::CreateSurface(void* windowHandle, VkInstance instance, VkSurfaceKHR* surface)
+void iOSVulkanPlatform::CreateSurface(Window* window, VkInstance instance, VkSurfaceKHR* surface)
 {
+    void* windowHandle = window->GetNativePtr();
 	// Create surface on a main UI Thread
 	Function<void()> func = [&windowHandle, &instance, &surface]()
 	{

Source/Engine/GraphicsDevice/Vulkan/iOS/iOSVulkanPlatform.h

@@ -18,7 +18,7 @@ class iOSVulkanPlatform : public VulkanPlatformBase
 {
 public:
 	static void GetInstanceExtensions(Array<const char*>& extensions, Array<const char*>& layers);
-	static void CreateSurface(void* windowHandle, VkInstance instance, VkSurfaceKHR* outSurface);
+	static void CreateSurface(Window* window, VkInstance instance, VkSurfaceKHR* outSurface);
 };
 
 typedef iOSVulkanPlatform VulkanPlatform;

Source/Engine/Input/Input.cpp

@@ -79,6 +79,7 @@ Delegate<const Float2&, MouseButton> Input::MouseUp;
 Delegate<const Float2&, MouseButton> Input::MouseDoubleClick;
 Delegate<const Float2&, float> Input::MouseWheel;
 Delegate<const Float2&> Input::MouseMove;
+Delegate<const Float2&> Input::MouseMoveRelative;
 Action Input::MouseLeave;
 Delegate<const Float2&, int32> Input::TouchDown;
 Delegate<const Float2&, int32> Input::TouchMove;
@@ -209,6 +210,14 @@ void Mouse::OnMouseMove(const Float2& position, Window* target)
     e.MouseData.Position = position;
 }
 
+void Mouse::OnMouseMoveRelative(const Float2& positionRelative, Window* target)
+{
+    Event& e = _queue.AddOne();
+    e.Type = EventType::MouseMoveRelative;
+    e.Target = target;
+    e.MouseMovementData.PositionRelative = positionRelative;
+}
+
 void Mouse::OnMouseLeave(Window* target)
 {
     Event& e = _queue.AddOne();
@@ -274,6 +283,11 @@ bool Mouse::Update(EventQueue& queue)
             _state.MousePosition = e.MouseData.Position;
             break;
         }
+        case EventType::MouseMoveRelative:
+        {
+            _state.MousePosition += e.MouseMovementData.PositionRelative;
+            break;
+        }
         case EventType::MouseLeave:
         {
             break;
@@ -731,6 +745,9 @@ void InputService::Update()
         case InputDevice::EventType::MouseMove:
             window->OnMouseMove(window->ScreenToClient(e.MouseData.Position));
             break;
+        case InputDevice::EventType::MouseMoveRelative:
+            window->OnMouseMoveRelative(e.MouseMovementData.PositionRelative);
+            break;
         case InputDevice::EventType::MouseLeave:
             window->OnMouseLeave();
             break;
@@ -787,6 +804,9 @@ void InputService::Update()
         case InputDevice::EventType::MouseMove:
             Input::MouseMove(e.MouseData.Position);
             break;
+        case InputDevice::EventType::MouseMoveRelative:
+            Input::MouseMoveRelative(e.MouseMovementData.PositionRelative);
+            break;
         case InputDevice::EventType::MouseLeave:
             Input::MouseLeave();
             break;
@@ -1000,12 +1020,14 @@ void InputService::Update()
         }
     }
 
+#if !PLATFORM_SDL
     // Lock mouse if need to
     const auto lockMode = Screen::GetCursorLock();
     if (lockMode == CursorLockMode::Locked)
     {
         Input::SetMousePosition(Screen::GetSize() * 0.5f);
     }
+#endif
 
     // Send events for the active actions and axes (send events only in play mode)
     if (!Time::GetGamePaused())

Source/Engine/Input/Input.h

@@ -107,6 +107,11 @@ public:
     /// </summary>
     API_EVENT() static Delegate<const Float2&> MouseMove;
 
+    /// <summary>
+    /// Event fired when mouse moves while in relative mode.
+    /// </summary>
+    API_EVENT() static Delegate<const Float2&> MouseMoveRelative;
+
     /// <summary>
     /// Event fired when mouse leaves window.
     /// </summary>

Source/Engine/Input/InputDevice.h

@@ -25,6 +25,7 @@ public:
         MouseDoubleClick,
         MouseWheel,
         MouseMove,
+        MouseMoveRelative,
         MouseLeave,
         TouchDown,
         TouchMove,
@@ -54,6 +55,11 @@ public:
                 Float2 Position;
             } MouseData;
 
+            struct
+            {
+                Float2 PositionRelative;
+            } MouseMovementData;
+
             struct
             {
                 float WheelDelta;

Source/Engine/Input/Mouse.h

@@ -46,12 +46,14 @@ public:
 protected:
     State _state;
     State _prevState;
+    bool _relativeMode;
 
     explicit Mouse()
         : InputDevice(SpawnParams(Guid::New(), TypeInitializer), TEXT("Mouse"))
     {
         _state.Clear();
         _prevState.Clear();
+        _relativeMode = false;
     }
 
 public:
@@ -114,6 +116,14 @@ public:
         return !_state.MouseButtons[static_cast<int32>(button)] && _prevState.MouseButtons[static_cast<int32>(button)];
     }
 
+    /// <summary>
+    /// Gets the current state of mouse relative mode. 
+    /// </summary>
+    API_FUNCTION() FORCE_INLINE bool IsRelative() const
+    {
+        return _relativeMode;
+    }
+
 public:
     /// <summary>
     /// Sets the mouse position.
@@ -121,6 +131,17 @@ public:
     /// <param name="newPosition">The new position.</param>
     virtual void SetMousePosition(const Float2& newPosition) = 0;
 
+    /// <summary>
+    /// Sets the mouse relative mode state. While enabled, the mouse movement tracking becomes more accurate.
+    /// The cursor will be hidden while in relative mode.
+    /// </summary>
+    /// <param name="relativeMode">The new relative mode state.</param>
+    /// <param name="window">The window.</param>
+    virtual void SetRelativeMode(bool relativeMode, Window* window)
+    {
+        _relativeMode = relativeMode;
+    }
+
     /// <summary>
     /// Called when mouse cursor gets moved by the application. Invalidates the previous cached mouse position to prevent mouse jitter when locking the cursor programmatically.
     /// </summary>
@@ -158,6 +179,13 @@ public:
     /// <param name="target">The target window to receive this event, otherwise input system will pick the window automatically.</param>
     void OnMouseMove(const Float2& position, Window* target = nullptr);
 
+    /// <summary>
+    /// Called when mouse moves in relative mode.
+    /// </summary>
+    /// <param name="positionRelative">The mouse position change.</param>
+    /// <param name="target">The target window to receive this event, otherwise input system will pick the window automatically.</param>
+    void OnMouseMoveRelative(const Float2& positionRelative, Window* target = nullptr);
+
     /// <summary>
     /// Called when mouse leaves the input source area.
     /// </summary>

Source/Engine/Platform/Base/Enums.h

@@ -0,0 +1,251 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#include "Engine/Core/Config.h"
+
+/// <summary>
+/// Window closing reasons.
+/// </summary>
+API_ENUM() enum class ClosingReason
+{
+    /// <summary>
+    /// The unknown.
+    /// </summary>
+    Unknown = 0,
+
+    /// <summary>
+    /// The user.
+    /// </summary>
+    User,
+
+    /// <summary>
+    /// The engine exit.
+    /// </summary>
+    EngineExit,
+
+    /// <summary>
+    /// The close event.
+    /// </summary>
+    CloseEvent,
+};
+
+/// <summary>
+/// Types of default cursors.
+/// </summary>
+API_ENUM() enum class CursorType
+{
+    /// <summary>
+    /// The default.
+    /// </summary>
+    Default = 0,
+
+    /// <summary>
+    /// The cross.
+    /// </summary>
+    Cross,
+
+    /// <summary>
+    /// The hand.
+    /// </summary>
+    Hand,
+
+    /// <summary>
+    /// The help icon
+    /// </summary>
+    Help,
+
+    /// <summary>
+    /// The I beam.
+    /// </summary>
+    IBeam,
+
+    /// <summary>
+    /// The blocking image.
+    /// </summary>
+    No,
+
+    /// <summary>
+    /// The wait.
+    /// </summary>
+    Wait,
+
+    /// <summary>
+    /// The size all sides.
+    /// </summary>
+    SizeAll,
+
+    /// <summary>
+    /// The size NE-SW.
+    /// </summary>
+    SizeNESW,
+
+    /// <summary>
+    /// The size NS.
+    /// </summary>
+    SizeNS,
+
+    /// <summary>
+    /// The size NW-SE.
+    /// </summary>
+    SizeNWSE,
+
+    /// <summary>
+    /// The size WE.
+    /// </summary>
+    SizeWE,
+
+    /// <summary>
+    /// The cursor is hidden.
+    /// </summary>
+    Hidden,
+
+    MAX
+};
+
+/// <summary>
+/// Data drag and drop effects.
+/// </summary>
+API_ENUM() enum class DragDropEffect
+{
+    /// <summary>
+    /// The none.
+    /// </summary>
+    None = 0,
+
+    /// <summary>
+    /// The copy.
+    /// </summary>
+    Copy,
+
+    /// <summary>
+    /// The move.
+    /// </summary>
+    Move,
+
+    /// <summary>
+    /// The link.
+    /// </summary>
+    Link,
+};
+
+/// <summary>
+/// Window hit test codes. Note: they are 1:1 mapping for Win32 values.
+/// </summary>
+API_ENUM() enum class WindowHitCodes
+{
+    /// <summary>
+    /// The transparent area.
+    /// </summary>
+    Transparent = -1,
+
+    /// <summary>
+    /// The no hit.
+    /// </summary>
+    NoWhere = 0,
+
+    /// <summary>
+    /// The client area.
+    /// </summary>
+    Client = 1,
+
+    /// <summary>
+    /// The caption area.
+    /// </summary>
+    Caption = 2,
+
+    /// <summary>
+    /// The system menu.
+    /// </summary>
+    SystemMenu = 3,
+
+    /// <summary>
+    /// The grow box
+    /// </summary>
+    GrowBox = 4,
+
+    /// <summary>
+    /// The menu.
+    /// </summary>
+    Menu = 5,
+
+    /// <summary>
+    /// The horizontal scroll.
+    /// </summary>
+    HScroll = 6,
+
+    /// <summary>
+    /// The vertical scroll.
+    /// </summary>
+    VScroll = 7,
+
+    /// <summary>
+    /// The minimize button.
+    /// </summary>
+    MinButton = 8,
+
+    /// <summary>
+    /// The maximize button.
+    /// </summary>
+    MaxButton = 9,
+
+    /// <summary>
+    /// The left side;
+    /// </summary>
+    Left = 10,
+
+    /// <summary>
+    /// The right side.
+    /// </summary>
+    Right = 11,
+
+    /// <summary>
+    /// The top side.
+    /// </summary>
+    Top = 12,
+
+    /// <summary>
+    /// The top left corner.
+    /// </summary>
+    TopLeft = 13,
+
+    /// <summary>
+    /// The top right corner.
+    /// </summary>
+    TopRight = 14,
+
+    /// <summary>
+    /// The bottom side.
+    /// </summary>
+    Bottom = 15,
+
+    /// <summary>
+    /// The bottom left corner.
+    /// </summary>
+    BottomLeft = 16,
+
+    /// <summary>
+    /// The bottom right corner.
+    /// </summary>
+    BottomRight = 17,
+
+    /// <summary>
+    /// The border.
+    /// </summary>
+    Border = 18,
+
+    /// <summary>
+    /// The object.
+    /// </summary>
+    Object = 19,
+
+    /// <summary>
+    /// The close button.
+    /// </summary>
+    Close = 20,
+
+    /// <summary>
+    /// The help button.
+    /// </summary>
+    Help = 21,
+};

Source/Engine/Platform/Base/PlatformBase.cpp

@@ -45,6 +45,7 @@ static_assert(sizeof(double) == 8, "Invalid double type size.");
 static_assert((PLATFORM_THREADS_LIMIT & (PLATFORM_THREADS_LIMIT - 1)) == 0, "Threads limit must be power of two.");
 static_assert(PLATFORM_THREADS_LIMIT % 4 == 0, "Threads limit must be multiple of 4.");
 
+const Char* PlatformBase::ApplicationClassName = TEXT("FlaxWindow");
 float PlatformBase::CustomDpiScale = 1.0f;
 Array<User*, FixedAllocation<8>> PlatformBase::Users;
 Delegate<User*> PlatformBase::UserAdded;

Source/Engine/Platform/Base/PlatformBase.h

@@ -166,6 +166,13 @@ DECLARE_SCRIPTING_TYPE_MINIMAL(PlatformBase);
     /// </summary>
     static void Exit();
 
+public:
+
+    /// <summary>
+    /// Application windows class name.
+    /// </summary>
+    static const Char* ApplicationClassName;
+
 public:
     /// <summary>
     /// Copy memory region

Source/Engine/Platform/Base/ScreenUtilitiesBase.h

@@ -0,0 +1,42 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#include "Engine/Core/Types/BaseTypes.h"
+#include "Engine/Core/Math/Color32.h"
+#include "Engine/Core/Math/Vector2.h"
+#include "Engine/Core/Delegate.h"
+
+API_INJECT_CODE(cpp, "#include \"Engine/Platform/ScreenUtilities.h\"");
+
+/// <summary>
+/// Platform-dependent screen utilities.
+/// </summary>
+API_CLASS(Static, Name="ScreenUtilities", Tag="NativeInvokeUseName")
+class FLAXENGINE_API ScreenUtilitiesBase
+{
+public:
+    static struct FLAXENGINE_API ScriptingTypeInitializer TypeInitializer;
+    
+    /// <summary>
+    /// Gets the pixel color at the specified coordinates.
+    /// </summary>
+    /// <param name="pos">Screen-space coordinate to read.</param>
+    /// <returns>Pixel color at the specified coordinates.</returns>
+    API_FUNCTION() static Color32 GetColorAt(const Float2& pos)
+    {
+        return Color32::Transparent;
+    }
+
+    /// <summary>
+    /// Starts async color picking. Color will be returned through PickColorDone event when the actions ends (user selected the final color with a mouse). When action is active, GetColorAt can be used to read the current value.
+    /// </summary>
+    API_FUNCTION() static void PickColor()
+    {
+    }
+
+    /// <summary>
+    /// Called when PickColor action is finished.
+    /// </summary>
+    API_EVENT() static Delegate<Color32> PickColorDone;
+};

Source/Engine/Platform/Base/WindowBase.cpp

@@ -106,7 +106,7 @@ WindowBase::WindowBase(const CreateWindowSettings& settings)
     if (settings.StartPosition == WindowStartPosition::CenterParent
         || settings.StartPosition == WindowStartPosition::CenterScreen)
     {
-        Rectangle parentBounds = Rectangle(Float2::Zero, Platform::GetDesktopSize());
+        Rectangle parentBounds = Platform::GetMonitorBounds(Float2::Minimum);
         if (settings.Parent != nullptr && settings.StartPosition == WindowStartPosition::CenterParent)
             parentBounds = settings.Parent->GetClientBounds();
 
@@ -257,6 +257,13 @@ void WindowBase::OnMouseMove(const Float2& mousePosition)
     INVOKE_EVENT_PARAMS_1(OnMouseMove, (void*)&mousePosition);
 }
 
+void WindowBase::OnMouseMoveRelative(const Float2& mousePositionRelative)
+{
+    PROFILE_CPU_NAMED("GUI.OnMouseMoveRelative");
+    MouseMoveRelative(mousePositionRelative);
+    INVOKE_EVENT_PARAMS_1(OnMouseMoveRelative, (void*)&mousePositionRelative);
+}
+
 void WindowBase::OnMouseLeave()
 {
     PROFILE_CPU_NAMED("GUI.OnMouseLeave");

Source/Engine/Platform/Base/WindowBase.h

@@ -8,6 +8,7 @@
 #include "Engine/Scripting/ScriptingObject.h"
 #include "Engine/Input/KeyboardKeys.h"
 #include "Engine/Input/Enums.h"
+#include "Enums.h"
 
 class Input;
 class Engine;
@@ -17,252 +18,6 @@ class GPUSwapChain;
 class TextureData;
 class IGuiData;
 
-/// <summary>
-/// Window closing reasons.
-/// </summary>
-API_ENUM() enum class ClosingReason
-{
-    /// <summary>
-    /// The unknown.
-    /// </summary>
-    Unknown = 0,
-
-    /// <summary>
-    /// The user.
-    /// </summary>
-    User,
-
-    /// <summary>
-    /// The engine exit.
-    /// </summary>
-    EngineExit,
-
-    /// <summary>
-    /// The close event.
-    /// </summary>
-    CloseEvent,
-};
-
-/// <summary>
-/// Types of default cursors.
-/// </summary>
-API_ENUM() enum class CursorType
-{
-    /// <summary>
-    /// The default.
-    /// </summary>
-    Default = 0,
-
-    /// <summary>
-    /// The cross.
-    /// </summary>
-    Cross,
-
-    /// <summary>
-    /// The hand.
-    /// </summary>
-    Hand,
-
-    /// <summary>
-    /// The help icon
-    /// </summary>
-    Help,
-
-    /// <summary>
-    /// The I beam.
-    /// </summary>
-    IBeam,
-
-    /// <summary>
-    /// The blocking image.
-    /// </summary>
-    No,
-
-    /// <summary>
-    /// The wait.
-    /// </summary>
-    Wait,
-
-    /// <summary>
-    /// The size all sides.
-    /// </summary>
-    SizeAll,
-
-    /// <summary>
-    /// The size NE-SW.
-    /// </summary>
-    SizeNESW,
-
-    /// <summary>
-    /// The size NS.
-    /// </summary>
-    SizeNS,
-
-    /// <summary>
-    /// The size NW-SE.
-    /// </summary>
-    SizeNWSE,
-
-    /// <summary>
-    /// The size WE.
-    /// </summary>
-    SizeWE,
-
-    /// <summary>
-    /// The cursor is hidden.
-    /// </summary>
-    Hidden,
-
-    MAX
-};
-
-/// <summary>
-/// Data drag and drop effects.
-/// </summary>
-API_ENUM() enum class DragDropEffect
-{
-    /// <summary>
-    /// The none.
-    /// </summary>
-    None = 0,
-
-    /// <summary>
-    /// The copy.
-    /// </summary>
-    Copy,
-
-    /// <summary>
-    /// The move.
-    /// </summary>
-    Move,
-
-    /// <summary>
-    /// The link.
-    /// </summary>
-    Link,
-};
-
-/// <summary>
-/// Window hit test codes. Note: they are 1:1 mapping for Win32 values.
-/// </summary>
-API_ENUM() enum class WindowHitCodes
-{
-    /// <summary>
-    /// The transparent area.
-    /// </summary>
-    Transparent = -1,
-
-    /// <summary>
-    /// The no hit.
-    /// </summary>
-    NoWhere = 0,
-
-    /// <summary>
-    /// The client area.
-    /// </summary>
-    Client = 1,
-
-    /// <summary>
-    /// The caption area.
-    /// </summary>
-    Caption = 2,
-
-    /// <summary>
-    /// The system menu.
-    /// </summary>
-    SystemMenu = 3,
-
-    /// <summary>
-    /// The grow box
-    /// </summary>
-    GrowBox = 4,
-
-    /// <summary>
-    /// The menu.
-    /// </summary>
-    Menu = 5,
-
-    /// <summary>
-    /// The horizontal scroll.
-    /// </summary>
-    HScroll = 6,
-
-    /// <summary>
-    /// The vertical scroll.
-    /// </summary>
-    VScroll = 7,
-
-    /// <summary>
-    /// The minimize button.
-    /// </summary>
-    MinButton = 8,
-
-    /// <summary>
-    /// The maximize button.
-    /// </summary>
-    MaxButton = 9,
-
-    /// <summary>
-    /// The left side;
-    /// </summary>
-    Left = 10,
-
-    /// <summary>
-    /// The right side.
-    /// </summary>
-    Right = 11,
-
-    /// <summary>
-    /// The top side.
-    /// </summary>
-    Top = 12,
-
-    /// <summary>
-    /// The top left corner.
-    /// </summary>
-    TopLeft = 13,
-
-    /// <summary>
-    /// The top right corner.
-    /// </summary>
-    TopRight = 14,
-
-    /// <summary>
-    /// The bottom side.
-    /// </summary>
-    Bottom = 15,
-
-    /// <summary>
-    /// The bottom left corner.
-    /// </summary>
-    BottomLeft = 16,
-
-    /// <summary>
-    /// The bottom right corner.
-    /// </summary>
-    BottomRight = 17,
-
-    /// <summary>
-    /// The border.
-    /// </summary>
-    Border = 18,
-
-    /// <summary>
-    /// The object.
-    /// </summary>
-    Object = 19,
-
-    /// <summary>
-    /// The close button.
-    /// </summary>
-    Close = 20,
-
-    /// <summary>
-    /// The help button.
-    /// </summary>
-    Help = 21,
-};
-
 API_INJECT_CODE(cpp, "#include \"Engine/Platform/Window.h\"");
 
 /// <summary>
@@ -837,6 +592,12 @@ public:
     MouseDelegate MouseMove;
     void OnMouseMove(const Float2& mousePosition);
 
+    /// <summary>
+    /// Event fired when mouse moves in relative mode.
+    /// </summary>
+    MouseDelegate MouseMoveRelative;
+    void OnMouseMoveRelative(const Float2& mousePositionRelative);
+
     /// <summary>
     /// Event fired when mouse leaves window.
     /// </summary>

Source/Engine/Platform/Clipboard.h

@@ -2,7 +2,9 @@
 
 #pragma once
 
-#if PLATFORM_WINDOWS
+#if PLATFORM_SDL && PLATFORM_LINUX
+#include "SDL/SDLClipboard.h"
+#elif PLATFORM_WINDOWS
 #include "Windows/WindowsClipboard.h"
 #elif PLATFORM_LINUX
 #include "Linux/LinuxClipboard.h"

Source/Engine/Platform/CreateWindowSettings.cs

@@ -21,7 +21,7 @@ namespace FlaxEngine
             AllowMinimize = true,
             AllowMaximize = true,
             AllowDragAndDrop = true,
-            IsRegularWindow = true,
+            Type = WindowType.Regular,
             HasSizingFrame = true,
             ShowAfterFirstPaint = true,
         };

Source/Engine/Platform/CreateWindowSettings.h

@@ -26,6 +26,32 @@ API_ENUM() enum class WindowStartPosition
     Manual,
 };
 
+/// <summary>
+/// Specifies the type of the window.
+/// </summary>
+API_ENUM() enum class WindowType
+{
+    /// <summary>
+    /// Regular window.
+    /// </summary>
+    Regular,
+
+    /// <summary>
+    /// Utility window.
+    /// </summary>
+    Utility,
+
+    /// <summary>
+    /// Tooltip window.
+    /// </summary>
+    Tooltip,
+
+    /// <summary>
+    /// Popup window.
+    /// </summary>
+    Popup,
+};
+
 /// <summary>
 /// Settings for new window.
 /// </summary>
@@ -119,9 +145,15 @@ DECLARE_SCRIPTING_TYPE_MINIMAL(CreateWindowSettings);
     API_FIELD() bool IsTopmost = false;
 
     /// <summary>
-    /// True if it's a regular window, false for tooltips, contextmenu and other utility windows.
+    /// True if it's a regular window, false for tooltips, context menu and other utility windows.
     /// </summary>
-    API_FIELD() bool IsRegularWindow = true;
+    API_FIELD() DEPRECATED("Use Type instead") bool IsRegularWindow = true;
+
+    /// <summary>
+    /// The type of window. The type affects the behaviour of the window in system level.
+    /// Note: Tooltip and Popup windows require Parent to be set.
+    /// </summary>
+    API_FIELD() WindowType Type = WindowType::Regular;
 
     /// <summary>
     /// Enable/disable window sizing frame.

Source/Engine/Platform/Defines.h

@@ -140,6 +140,9 @@ API_ENUM() enum class ArchitectureType
 #if !defined(PLATFORM_SWITCH)
 #define PLATFORM_SWITCH 0
 #endif
+#if !defined(PLATFORM_SDL)
+#define PLATFORM_SDL 0
+#endif
 
 #if PLATFORM_WINDOWS
 #include "Windows/WindowsDefines.h"

Source/Engine/Platform/GDK/GDKPlatform.cpp

@@ -30,7 +30,6 @@ inline bool operator==(const APP_LOCAL_DEVICE_ID& l, const APP_LOCAL_DEVICE_ID&
     return Platform::MemoryCompare(&l, &r, sizeof(APP_LOCAL_DEVICE_ID)) == 0;
 }
 
-const Char* GDKPlatform::ApplicationWindowClass = TEXT("FlaxWindow");
 void* GDKPlatform::Instance = nullptr;
 Delegate<> GDKPlatform::Suspended;
 Delegate<> GDKPlatform::Resumed;
@@ -316,7 +315,7 @@ void GDKPlatform::PreInit(void* hInstance)
     windowsClass.style = CS_HREDRAW | CS_VREDRAW;
     windowsClass.lpfnWndProc = WndProc;
     windowsClass.hInstance = (HINSTANCE)Instance;
-    windowsClass.lpszClassName = ApplicationWindowClass;
+    windowsClass.lpszClassName = ApplicationClassName;
     if (!RegisterClassW(&windowsClass))
     {
         Error(TEXT("Window class registration failed!"));
@@ -474,7 +473,7 @@ void GDKPlatform::Exit()
     if (PlmSignalResume)
         CloseHandle(PlmSignalResume);
 
-    UnregisterClassW(ApplicationWindowClass, nullptr);
+    UnregisterClassW(ApplicationClassName, nullptr);
 
     XGameRuntimeUninitialize();
 }

Source/Engine/Platform/GDK/GDKPlatform.h

@@ -13,11 +13,6 @@ class FLAXENGINE_API GDKPlatform : public Win32Platform
 {
 public:
 
-    /// <summary>
-    /// Win32 application windows class name.
-    /// </summary>
-    static const Char* ApplicationWindowClass;
-
     /// <summary>
     /// Handle to Win32 application instance.
     /// </summary>

Source/Engine/Platform/GDK/GDKWindow.cpp

@@ -71,7 +71,7 @@ GDKWindow::GDKWindow(const CreateWindowSettings& settings)
     // Creating the window
     _handle = CreateWindowExW(
         exStyle,
-        Platform::ApplicationWindowClass,
+        Platform::ApplicationClassName,
         settings.Title.GetText(),
         style,
         x,

Source/Engine/Platform/Linux/IncludeX11.h

@@ -21,6 +21,7 @@ namespace X11
 #include <X11/Xresource.h>
 #include <X11/extensions/Xinerama.h>
 #include <X11/Xcursor/Xcursor.h>
+#include <X11/extensions/Xfixes.h>
 }
 
 // Helper macros

Source/Engine/Platform/Linux/LinuxPlatform.cpp

@@ -93,7 +93,9 @@ X11::Cursor Cursors[(int32)CursorType::MAX];
 X11::XcursorImage* CursorsImg[(int32)CursorType::MAX];
 Dictionary<StringAnsi, X11::KeyCode> KeyNameMap;
 Array<KeyboardKeys> KeyCodeMap;
-Delegate<void*> LinuxPlatform::xEventRecieved;
+#if !PLATFORM_SDL
+Delegate<void*> LinuxPlatform::xEventReceived;
+#endif
 Window* MouseTrackingWindow = nullptr;
 
 // Message boxes configuration
@@ -651,7 +653,11 @@ static int X11_MessageBoxLoop(MessageBoxData* data)
 	return 0;
 }
 
+#if !PLATFORM_SDL
 DialogResult MessageBox::Show(Window* parent, const StringView& text, const StringView& caption, MessageBoxButtons buttons, MessageBoxIcon icon)
+#else
+DialogResult MessageBox::ShowFallback(Window* parent, const StringView& text, const StringView& caption, MessageBoxButtons buttons, MessageBoxIcon icon)
+#endif
 {
     if (CommandLine::Options.Headless)
         return DialogResult::None;
@@ -838,6 +844,8 @@ DialogResult MessageBox::Show(Window* parent, const StringView& text, const Stri
 	return data.resultButtonIndex == -1 ? DialogResult::None : data.buttons[data.resultButtonIndex].result;
 }
 
+#if !PLATFORM_SDL
+
 int X11ErrorHandler(X11::Display* display, X11::XErrorEvent* event)
 {
     if (event->error_code == 5)
@@ -848,6 +856,8 @@ int X11ErrorHandler(X11::Display* display, X11::XErrorEvent* event)
 	return 0;
 }
 
+#endif
+
 int32 CalculateDpi()
 {
 	int dpi = 96;
@@ -1203,17 +1213,20 @@ public:
     }
 };
 
+#if !PLATFORM_SDL
 struct Property
 {
-	unsigned char* data;
-	int format, nitems;
-	X11::Atom type;
+    unsigned char* data;
+    int format, nitems;
+    X11::Atom type;
 };
+#endif
 
 namespace Impl
 {
 	LinuxKeyboard* Keyboard;
 	LinuxMouse* Mouse;
+#if !PLATFORM_SDL
     StringAnsi ClipboardText;
 
     void ClipboardGetText(String& result, X11::Atom source, X11::Atom atom, X11::Window window)
@@ -1328,8 +1341,10 @@ namespace Impl
         X11::XQueryPointer(display, w, &wtmp, &child, &tmp, &tmp, &tmp, &tmp, &utmp);
         return FindAppWindow(display, child);
     }
+#endif
 }
 
+#if !PLATFORM_SDL
 class LinuxDropFilesData : public IGuiData
 {
 public:
@@ -1367,7 +1382,7 @@ public:
     }
 };
 
-DragDropEffect LinuxWindow::DoDragDrop(const StringView& data)
+DragDropEffect Window::DoDragDrop(const StringView& data)
 {
     if (CommandLine::Options.Headless)
         return DragDropEffect::None;
@@ -1381,13 +1396,18 @@ DragDropEffect LinuxWindow::DoDragDrop(const StringView& data)
     StringAnsi dataAnsi(data);
     LinuxDropTextData dropData;
     dropData.Text = data;
+#if !PLATFORM_SDL
+    unsigned long mainWindow = _window;
+#else
+    unsigned long mainWindow = (unsigned long)_handle;
+#endif
 
     // Begin dragging
 	auto screen = X11::XDefaultScreen(xDisplay);
 	auto rootWindow = X11::XRootWindow(xDisplay, screen);
-    if (X11::XGrabPointer(xDisplay, _window, 1, Button1MotionMask | ButtonReleaseMask, GrabModeAsync, GrabModeAsync, rootWindow, cursorWrong, CurrentTime) != GrabSuccess)
+    if (X11::XGrabPointer(xDisplay, mainWindow, 1, Button1MotionMask | ButtonReleaseMask, GrabModeAsync, GrabModeAsync, rootWindow, cursorWrong, CurrentTime) != GrabSuccess)
 	    return DragDropEffect::None;
-    X11::XSetSelectionOwner(xDisplay, xAtomXdndSelection, _window, CurrentTime);
+    X11::XSetSelectionOwner(xDisplay, xAtomXdndSelection, mainWindow, CurrentTime);
 
     // Process events
     X11::XEvent event;
@@ -1495,7 +1515,7 @@ DragDropEffect LinuxWindow::DoDragDrop(const StringView& data)
                     m.window = previousWindow;
                     m.message_type = xAtomXdndLeave;
                     m.format = 32;
-                    m.data.l[0] = _window;
+                    m.data.l[0] = mainWindow;
                     m.data.l[1] = 0;
                     m.data.l[2] = 0;
                     m.data.l[3] = 0;
@@ -1524,7 +1544,7 @@ DragDropEffect LinuxWindow::DoDragDrop(const StringView& data)
                     m.window = window;
                     m.message_type = xAtomXdndEnter;
                     m.format = 32;
-                    m.data.l[0] = _window;
+                    m.data.l[0] = mainWindow;
                     m.data.l[1] = Math::Min(5, version) << 24  | (formats.Count() > 3);
                     m.data.l[2] = formats.Count() > 0 ? formats[0] : 0;
                     m.data.l[3] = formats.Count() > 1 ? formats[1] : 0;
@@ -1559,7 +1579,7 @@ DragDropEffect LinuxWindow::DoDragDrop(const StringView& data)
                     m.window = window;
                     m.message_type = xAtomXdndPosition;
                     m.format = 32;
-                    m.data.l[0] = _window;
+                    m.data.l[0] = mainWindow;
                     m.data.l[1] = 0;
                     m.data.l[2] = (x << 16) | y;
                     m.data.l[3] = CurrentTime;
@@ -1602,7 +1622,7 @@ DragDropEffect LinuxWindow::DoDragDrop(const StringView& data)
                     m.window = previousWindow;
                     m.message_type = xAtomXdndDrop;
                     m.format = 32;
-                    m.data.l[0] = _window;
+                    m.data.l[0] = mainWindow;
                     m.data.l[1] = 0;
                     m.data.l[2] = CurrentTime;
                     m.data.l[3] = 0;
@@ -1649,7 +1669,7 @@ DragDropEffect LinuxWindow::DoDragDrop(const StringView& data)
             m.window = previousWindow;
             m.message_type = xAtomXdndLeave;
             m.format = 32;
-            m.data.l[0] = _window;
+            m.data.l[0] = mainWindow;
             m.data.l[1] = 0;
             m.data.l[2] = 0;
             m.data.l[3] = 0;
@@ -1675,7 +1695,7 @@ void LinuxClipboard::SetText(const StringView& text)
 {
     if (CommandLine::Options.Headless)
         return;
-    auto mainWindow = (LinuxWindow*)Engine::MainWindow;
+    auto mainWindow = Engine::MainWindow;
     if (!mainWindow)
         return;
     X11::Window window = (X11::Window)mainWindow->GetNativePtr();
@@ -1698,7 +1718,7 @@ String LinuxClipboard::GetText()
     if (CommandLine::Options.Headless)
         return String::Empty;
     String result;
-    auto mainWindow = (LinuxWindow*)Engine::MainWindow;
+    auto mainWindow = Engine::MainWindow;
     if (!mainWindow)
         return result;
     X11::Window window = (X11::Window)mainWindow->GetNativePtr();
@@ -1727,9 +1747,11 @@ Array<String> LinuxClipboard::GetFiles()
     return Array<String>();
 }
 
+#endif
+
 void* LinuxPlatform::GetXDisplay()
 {
-	return xDisplay;
+    return xDisplay;
 }
 
 bool LinuxPlatform::CreateMutex(const Char* name)
@@ -2090,6 +2112,7 @@ bool LinuxPlatform::Init()
         DeviceId.D = (uint32)UnixCpu.ClockSpeed * UnixCpu.LogicalProcessorCount * UnixCpu.ProcessorCoreCount * UnixCpu.CacheLineSize;
     }
 
+#if !PLATFORM_SDL
     // Get user locale string
     setlocale(LC_ALL, "");
     const char* locale = setlocale(LC_CTYPE, NULL);
@@ -2099,6 +2122,7 @@ bool LinuxPlatform::Init()
     UserLocale.Replace('_', '-');
     if (UserLocale == TEXT("C"))
         UserLocale = TEXT("en");
+#endif
 
     // Get computer name string
     gethostname(buffer, UNIX_APP_BUFF_SIZE);
@@ -2117,10 +2141,15 @@ bool LinuxPlatform::Init()
 	Platform::MemoryClear(Cursors, sizeof(Cursors));
 	Platform::MemoryClear(CursorsImg, sizeof(CursorsImg));
 
+
     // Skip setup if running in headless mode (X11 might not be available on servers)
     if (CommandLine::Options.Headless)
         return false;
-
+#if PLATFORM_SDL
+    xDisplay = X11::XOpenDisplay(nullptr);
+#endif
+    
+#if !PLATFORM_SDL
 	X11::XInitThreads();
 
 	xDisplay = X11::XOpenDisplay(nullptr);
@@ -2259,7 +2288,7 @@ bool LinuxPlatform::Init()
     Input::Mouse = Impl::Mouse = New<LinuxMouse>();
     Input::Keyboard = Impl::Keyboard = New<LinuxKeyboard>();
 	LinuxInput::Init();
-
+#endif
     return false;
 }
 
@@ -2269,6 +2298,7 @@ void LinuxPlatform::BeforeRun()
 
 void LinuxPlatform::Tick()
 {
+#if !PLATFORM_SDL
 	UnixPlatform::Tick();
 
 	LinuxInput::UpdateState();
@@ -2285,9 +2315,9 @@ void LinuxPlatform::Tick()
 			continue;
 
         // External event handling
-		xEventRecieved(&event);
+		xEventReceived(&event);
 
-		LinuxWindow* window;
+		Window* window;
 		switch (event.type)
 		{
 			case ClientMessage:
@@ -2619,6 +2649,7 @@ void LinuxPlatform::Tick()
 	}
 
 	//X11::XFlush(xDisplay);
+#endif
 }
 
 void LinuxPlatform::BeforeExit()
@@ -2627,6 +2658,7 @@ void LinuxPlatform::BeforeExit()
 
 void LinuxPlatform::Exit()
 {
+#if !PLATFORM_SDL
 	for (int32 i = 0; i < (int32)CursorType::MAX; i++)
 	{
 		if (Cursors[i])
@@ -2652,8 +2684,10 @@ void LinuxPlatform::Exit()
 		X11::XCloseDisplay(xDisplay);
 		xDisplay = nullptr;
 	}
+#endif
 }
 
+#if !PLATFORM_SDL
 int32 LinuxPlatform::GetDpi()
 {
     return SystemDpi;
@@ -2663,6 +2697,7 @@ String LinuxPlatform::GetUserLocaleName()
 {
     return UserLocale;
 }
+#endif
 
 String LinuxPlatform::GetComputerName()
 {
@@ -2870,10 +2905,12 @@ bool LinuxPlatform::SetWorkingDirectory(const String& path)
     return chdir(StringAsANSI<>(*path).Get()) != 0;
 }
 
+#if !PLATFORM_SDL
 Window* LinuxPlatform::CreateWindow(const CreateWindowSettings& settings)
 {
     return New<LinuxWindow>(settings);
 }
+#endif
 
 extern char **environ;
 

Source/Engine/Platform/Linux/LinuxPlatform.h

@@ -36,7 +36,7 @@ public:
     /// <summary>
     /// An event that is fired when an XEvent is received during platform tick.
     /// </summary>
-    static Delegate<void*> xEventRecieved;
+    static Delegate<void*> xEventReceived;
 
 public:
 
@@ -122,8 +122,10 @@ public:
     static void Tick();
     static void BeforeExit();
     static void Exit();
+#if !PLATFORM_SDL
     static int32 GetDpi();
     static String GetUserLocaleName();
+#endif
     static String GetComputerName();
     static bool GetHasFocus();
     static bool CanOpenUrl(const StringView& url);
@@ -138,7 +140,9 @@ public:
     static Guid GetUniqueDeviceId();
     static String GetWorkingDirectory();
     static bool SetWorkingDirectory(const String& path);
+#if !PLATFORM_SDL
     static Window* CreateWindow(const CreateWindowSettings& settings);
+#endif
     static void GetEnvironmentVariables(Dictionary<String, String, HeapAllocation>& result);
     static bool GetEnvironmentVariable(const String& name, String& value);
     static bool SetEnvironmentVariable(const String& name, const String& value);

Source/Engine/Platform/Linux/LinuxScreenUtilities.cpp

@@ -0,0 +1,94 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+#if USE_EDITOR && PLATFORM_LINUX
+
+#include "Engine/Platform/Types.h"
+#include "Engine/Platform/ScreenUtilities.h"
+#include "Engine/Core/Math/Vector2.h"
+#include "Engine/Core/Delegate.h"
+#include "Engine/Core/Log.h"
+#include "Engine/Profiler/ProfilerCPU.h"
+#include "Engine/Platform/Linux/LinuxPlatform.h"
+#include "Engine/Platform/Linux/IncludeX11.h"
+
+Delegate<Color32> ScreenUtilitiesBase::PickColorDone;
+
+Color32 LinuxScreenUtilities::GetColorAt(const Float2& pos)
+{
+    X11::Display* display = (X11::Display*)Platform::GetXDisplay();
+    if (display)
+    {
+        int defaultScreen = X11::XDefaultScreen(display);
+        X11::Window rootWindow = X11::XRootWindow(display, defaultScreen);
+        X11::XImage* image = X11::XGetImage(display, rootWindow, (int)pos.X, (int)pos.Y, 1, 1, AllPlanes, XYPixmap);
+        if (image)
+        {
+            X11::XColor color;
+            color.pixel = XGetPixel(image, 0, 0);
+            X11::XFree(image);
+
+            X11::XQueryColor(display, X11::XDefaultColormap(display, defaultScreen), &color);
+
+            Color32 outputColor;
+            outputColor.R = color.red / 256;
+            outputColor.G = color.green / 256;
+            outputColor.B = color.blue / 256;
+            outputColor.A = 255;
+            return outputColor;
+        }
+        else
+        {
+            // XWayland doesn't support XGetImage...
+            // TODO: Fallback to Wayland implementation here?
+            return Color32::Black;
+        }
+    }
+    else
+    {
+        // TODO: Wayland
+        ASSERT(false);
+    }
+}
+
+void OnScreenUtilsXEventCallback(void* eventPtr)
+{
+    X11::XEvent* event = (X11::XEvent*) eventPtr;
+    X11::Display* display = (X11::Display*)Platform::GetXDisplay();
+    if (event->type == ButtonPress)
+    {
+        const Float2 cursorPos = Platform::GetMousePosition();
+        const Color32 colorPicked = ScreenUtilities::GetColorAt(cursorPos);
+        X11::XUngrabPointer(display, CurrentTime);
+        ScreenUtilities::PickColorDone(colorPicked);
+        LinuxPlatform::xEventReceived.Unbind(OnScreenUtilsXEventCallback);
+    }
+}
+
+void LinuxScreenUtilities::PickColor()
+{
+    PROFILE_CPU();
+    X11::Display* display = (X11::Display*)Platform::GetXDisplay();
+    if (display)
+    {
+        X11::Window rootWindow = X11::XRootWindow(display, X11::XDefaultScreen(display));
+
+        X11::Cursor cursor = XCreateFontCursor(display, 130);
+        int grabbedPointer = X11::XGrabPointer(display, rootWindow, 0,  ButtonPressMask, GrabModeAsync, GrabModeAsync, rootWindow, cursor, CurrentTime);
+        if (grabbedPointer != GrabSuccess)
+        {
+            LOG(Error, "Failed to grab cursor for events.");
+            X11::XFreeCursor(display, cursor);
+            return;
+        }
+
+        X11::XFreeCursor(display, cursor);
+        LinuxPlatform::xEventReceived.Bind(OnScreenUtilsXEventCallback);
+    }
+    else
+    {
+        // TODO: Wayland
+        ASSERT(false);
+    }
+}
+
+#endif

Source/Engine/Platform/Linux/LinuxScreenUtilities.h

@@ -0,0 +1,25 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#if USE_EDITOR && PLATFORM_LINUX
+
+#include "Engine/Platform/Base/ScreenUtilitiesBase.h"
+#include "Engine/Core/Types/BaseTypes.h"
+#include "Engine/Core/Math/Color32.h"
+#include "Engine/Core/Math/Vector2.h"
+#include "Engine/Core/Delegate.h"
+
+/// <summary>
+/// Platform-dependent screen utilities.
+/// </summary>
+class FLAXENGINE_API LinuxScreenUtilities : public ScreenUtilitiesBase
+{
+public:
+    
+    // [ScreenUtilitiesBase]
+    static Color32 GetColorAt(const Float2& pos);
+    static void PickColor();
+};
+
+#endif

Source/Engine/Platform/Linux/LinuxWindow.cpp

@@ -1,6 +1,6 @@
 // Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
 
-#if PLATFORM_LINUX
+#if PLATFORM_LINUX && !PLATFORM_SDL
 
 #include "../Window.h"
 #include "Engine/Input/Input.h"
@@ -617,7 +617,7 @@ void LinuxWindow::OnButtonPress(void* event)
 	}
 
 	// Handle double-click
-	if (buttonEvent->button == Button1)
+	if (buttonEvent->button == Button1 && !Input::Mouse->IsRelative())
 	{
 		if (
 			buttonEvent->time < (MouseLastButtonPressTime + MouseDoubleClickTime) &&

Source/Engine/Platform/Mac/MacScreenUtilities.cpp

@@ -0,0 +1,29 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+#if USE_EDITOR && PLATFORM_MAC
+
+#include "Engine/Platform/Types.h"
+#include "Engine/Platform/ScreenUtilities.h"
+#include "Engine/Core/Math/Vector2.h"
+#include "Engine/Core/Delegate.h"
+#include "Engine/Core/Log.h"
+
+#include <Cocoa/Cocoa.h>
+#include <AppKit/AppKit.h>
+
+Delegate<Color32> ScreenUtilitiesBase::PickColorDone;
+
+Color32 MacScreenUtilities::GetColorAt(const Float2& pos)
+{
+    // TODO: implement ScreenUtilities for macOS
+    return { 0, 0, 0, 255 };
+}
+
+void MacScreenUtilities::PickColor()
+{
+    // This is what C# calls to start the color picking sequence
+    // This should stop mouse clicks from working for one click, and that click is on the selected color
+    // There is a class called NSColorSample that might implement that for you, but maybe not.
+}
+
+#endif

Source/Engine/Platform/Mac/MacScreenUtilities.h

@@ -0,0 +1,25 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#if USE_EDITOR && PLATFORM_MAC
+
+#include "Engine/Platform/Base/ScreenUtilitiesBase.h"
+#include "Engine/Core/Types/BaseTypes.h"
+#include "Engine/Core/Math/Color32.h"
+#include "Engine/Core/Math/Vector2.h"
+#include "Engine/Core/Delegate.h"
+
+/// <summary>
+/// Platform-dependent screen utilities.
+/// </summary>
+class FLAXENGINE_API MacScreenUtilities : public ScreenUtilitiesBase
+{
+public:
+
+    // [ScreenUtilitiesBase]
+    static Color32 GetColorAt(const Float2& pos);
+    static void PickColor();
+};
+
+#endif

Source/Engine/Platform/Mac/MacWindow.cpp

@@ -507,7 +507,7 @@ static void ConvertNSRect(NSScreen *screen, NSRect *r)
 	Float2 mousePos = GetMousePosition(Window, event);
     mousePos = Window->ClientToScreen(mousePos);
     MouseButton mouseButton = MouseButton::Left;
-    if ([event clickCount] == 2)
+    if ([event clickCount] == 2 && !Input::Mouse->IsRelative())
         Input::Mouse->OnMouseDoubleClick(mousePos, mouseButton, Window);
     else
 	    Input::Mouse->OnMouseDown(mousePos, mouseButton, Window);
@@ -544,7 +544,7 @@ static void ConvertNSRect(NSScreen *screen, NSRect *r)
     if (IsWindowInvalid(Window)) return;
 	Float2 mousePos = GetMousePosition(Window, event);
     MouseButton mouseButton = MouseButton::Right;
-    if ([event clickCount] == 2)
+    if ([event clickCount] == 2 && !Input::Mouse->IsRelative())
         Input::Mouse->OnMouseDoubleClick(Window->ClientToScreen(mousePos), mouseButton, Window);
     else
 	    Input::Mouse->OnMouseDown(Window->ClientToScreen(mousePos), mouseButton, Window);
@@ -582,7 +582,7 @@ static void ConvertNSRect(NSScreen *screen, NSRect *r)
     default:
         return;
     }
-    if ([event clickCount] == 2)
+    if ([event clickCount] == 2 && !Input::Mouse->IsRelative())
         Input::Mouse->OnMouseDoubleClick(Window->ClientToScreen(mousePos), mouseButton, Window);
     else
 	    Input::Mouse->OnMouseDown(Window->ClientToScreen(mousePos), mouseButton, Window);

Source/Engine/Platform/MessageBox.h

@@ -237,4 +237,9 @@ DECLARE_SCRIPTING_TYPE_NO_SPAWN(MessageBox);
     /// <param name="icon">One of the MessageBoxIcon values that specifies which icon to display in the message box.</param>
     /// <returns>The message box dialog result.</returns>
     API_FUNCTION() static DialogResult Show(Window* parent, const StringView& text, const StringView& caption, MessageBoxButtons buttons, MessageBoxIcon icon);
+
+private:
+#if PLATFORM_SDL && PLATFORM_LINUX
+    static DialogResult ShowFallback(Window* parent, const StringView& text, const StringView& caption, MessageBoxButtons buttons, MessageBoxIcon icon);
+#endif
 };

Source/Engine/Platform/Platform.Build.cs

@@ -89,6 +89,19 @@ public class Platform : EngineModule
             break;
         default: throw new InvalidPlatformException(options.Platform.Target);
         }
+
+        if (EngineConfiguration.WithSDL(options))
+        {
+            switch (options.Platform.Target)
+            {
+            case TargetPlatform.Windows:
+            case TargetPlatform.Linux:
+            case TargetPlatform.Mac:
+                options.PublicDependencies.Add("SDL");
+                options.SourcePaths.Add(Path.Combine(FolderPath, "SDL"));
+                break;
+            }
+        }
         if (options.Target.IsEditor)
         {
             // Include platform settings headers

Source/Engine/Platform/Platform.h

@@ -8,7 +8,9 @@
 #include "Types.h"
 #include "Defines.h"
 
-#if PLATFORM_WINDOWS
+#if PLATFORM_SDL
+#include "SDL/SDLPlatform.h"
+#elif PLATFORM_WINDOWS
 #include "Windows/WindowsPlatform.h"
 #elif PLATFORM_UWP
 #include "UWP/UWPPlatform.h"

Source/Engine/Platform/SDL/SDLClipboard.h

@@ -0,0 +1,26 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#if PLATFORM_SDL && PLATFORM_LINUX
+
+#include "Engine/Platform/Base/ClipboardBase.h"
+
+/// <summary>
+/// SDL implementation of the clipboard service for Linux platform.
+/// </summary>
+class FLAXENGINE_API SDLClipboard : public ClipboardBase
+{
+public:
+
+    // [ClipboardBase]
+    static void Clear();
+    static void SetText(const StringView& text);
+    static void SetRawData(const Span<byte>& data);
+    static void SetFiles(const Array<String>& files);
+    static String GetText();
+    static Array<byte> GetRawData();
+    static Array<String> GetFiles();
+};
+
+#endif

Source/Engine/Platform/SDL/SDLInput.cpp

@@ -0,0 +1,792 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+#if PLATFORM_SDL
+
+#include "SDLInput.h"
+#include "SDLWindow.h"
+#include "Engine/Core/Collections/Dictionary.h"
+#include "Engine/Core/Log.h"
+#include "Engine/Input/Input.h"
+#include "Engine/Input/Mouse.h"
+#include "Engine/Input/Keyboard.h"
+#include "Engine/Input/Gamepad.h"
+
+#include <SDL3/SDL_events.h>
+
+class SDLMouse;
+class SDLKeyboard;
+class SDLGamepad;
+
+// TODO: Turn these into customizable values
+#define TRIGGER_THRESHOLD 30
+#define LEFT_STICK_THRESHOLD 7849
+#define RIGHT_STICK_THRESHOLD 8689
+
+namespace SDLInputImpl
+{
+    SDLMouse* Mouse = nullptr;
+    SDLKeyboard* Keyboard = nullptr;
+    Dictionary<SDL_JoystickID, SDLGamepad*> Gamepads;
+}
+
+static const KeyboardKeys SDL_TO_FLAX_KEYS_MAP[] =
+{
+    KeyboardKeys::None, // SDL_SCANCODE_UNKNOWN
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::A,
+    KeyboardKeys::B,
+    KeyboardKeys::C,
+    KeyboardKeys::D,
+    KeyboardKeys::E,
+    KeyboardKeys::F,
+    KeyboardKeys::G,
+    KeyboardKeys::H,
+    KeyboardKeys::I,
+    KeyboardKeys::J,
+    KeyboardKeys::K,
+    KeyboardKeys::L,
+    KeyboardKeys::M,
+    KeyboardKeys::N,
+    KeyboardKeys::O,
+    KeyboardKeys::P,
+    KeyboardKeys::Q,
+    KeyboardKeys::R,
+    KeyboardKeys::S,
+    KeyboardKeys::T,
+    KeyboardKeys::U,
+    KeyboardKeys::V,
+    KeyboardKeys::W,
+    KeyboardKeys::X,
+    KeyboardKeys::Y,
+    KeyboardKeys::Z, // 29
+    KeyboardKeys::Alpha1,
+    KeyboardKeys::Alpha2,
+    KeyboardKeys::Alpha3,
+    KeyboardKeys::Alpha4,
+    KeyboardKeys::Alpha5,
+    KeyboardKeys::Alpha6,
+    KeyboardKeys::Alpha7,
+    KeyboardKeys::Alpha8,
+    KeyboardKeys::Alpha9,
+    KeyboardKeys::Alpha0, // 39
+    KeyboardKeys::Return,
+    KeyboardKeys::Escape,
+    KeyboardKeys::Backspace,
+    KeyboardKeys::Tab,
+    KeyboardKeys::Spacebar,
+    KeyboardKeys::Minus,
+    KeyboardKeys::None, //KeyboardKeys::Equals, // ?
+    KeyboardKeys::LeftBracket,
+    KeyboardKeys::RightBracket,
+    KeyboardKeys::Backslash, // SDL_SCANCODE_BACKSLASH ?
+    KeyboardKeys::Oem102, // SDL_SCANCODE_NONUSHASH ?
+    KeyboardKeys::Colon, // SDL_SCANCODE_SEMICOLON ?
+    KeyboardKeys::Quote, // SDL_SCANCODE_APOSTROPHE
+    KeyboardKeys::BackQuote, // SDL_SCANCODE_GRAVE
+    KeyboardKeys::Comma,
+    KeyboardKeys::Period,
+    KeyboardKeys::Slash,
+    KeyboardKeys::Capital,
+    KeyboardKeys::F1,
+    KeyboardKeys::F2,
+    KeyboardKeys::F3,
+    KeyboardKeys::F4,
+    KeyboardKeys::F5,
+    KeyboardKeys::F6,
+    KeyboardKeys::F7,
+    KeyboardKeys::F8,
+    KeyboardKeys::F9,
+    KeyboardKeys::F10,
+    KeyboardKeys::F11,
+    KeyboardKeys::F12,
+    KeyboardKeys::PrintScreen,
+    KeyboardKeys::Scroll,
+    KeyboardKeys::Pause,
+    KeyboardKeys::Insert,
+    KeyboardKeys::Home,
+    KeyboardKeys::PageUp,
+    KeyboardKeys::Delete,
+    KeyboardKeys::End,
+    KeyboardKeys::PageDown,
+    KeyboardKeys::ArrowRight,
+    KeyboardKeys::ArrowLeft,
+    KeyboardKeys::ArrowDown,
+    KeyboardKeys::ArrowUp,
+    KeyboardKeys::Numlock,
+    KeyboardKeys::NumpadDivide,
+    KeyboardKeys::NumpadMultiply,
+    KeyboardKeys::NumpadSubtract,
+    KeyboardKeys::NumpadAdd,
+    KeyboardKeys::Return, // SDL_SCANCODE_KP_ENTER ?
+    KeyboardKeys::Numpad1,
+    KeyboardKeys::Numpad2,
+    KeyboardKeys::Numpad3,
+    KeyboardKeys::Numpad4,
+    KeyboardKeys::Numpad5,
+    KeyboardKeys::Numpad6,
+    KeyboardKeys::Numpad7,
+    KeyboardKeys::Numpad8,
+    KeyboardKeys::Numpad9,
+    KeyboardKeys::Numpad0, //98
+    KeyboardKeys::NumpadDecimal, // SDL_SCANCODE_KP_PERIOD
+    KeyboardKeys::Backslash, // SDL_SCANCODE_NONUSBACKSLASH ?
+    KeyboardKeys::Applications,
+    KeyboardKeys::Sleep, // SDL_SCANCODE_POWER ?
+    KeyboardKeys::None, // SDL_SCANCODE_KP_EQUALS ?
+    KeyboardKeys::F13,
+    KeyboardKeys::F14,
+    KeyboardKeys::F15,
+    KeyboardKeys::F16,
+    KeyboardKeys::F17,
+    KeyboardKeys::F18,
+    KeyboardKeys::F19,
+    KeyboardKeys::F20,
+    KeyboardKeys::F21,
+    KeyboardKeys::F22,
+    KeyboardKeys::F23,
+    KeyboardKeys::F24,
+    KeyboardKeys::Execute,
+    KeyboardKeys::Help,
+    KeyboardKeys::LeftMenu, // SDL_SCANCODE_MENU ?
+    KeyboardKeys::Select,
+    KeyboardKeys::None, // SDL_SCANCODE_STOP
+    KeyboardKeys::None, // SDL_SCANCODE_AGAIN
+    KeyboardKeys::None, // SDL_SCANCODE_UNDO
+    KeyboardKeys::None, // SDL_SCANCODE_CUT
+    KeyboardKeys::None, // SDL_SCANCODE_COPY
+    KeyboardKeys::None, // SDL_SCANCODE_PASTE
+    KeyboardKeys::None, // SDL_SCANCODE_FIND
+    KeyboardKeys::None, // SDL_SCANCODE_MUTE
+    KeyboardKeys::None, // SDL_SCANCODE_VOLUMEUP
+    KeyboardKeys::None, // SDL_SCANCODE_VOLUMEDOWN
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::NumpadSeparator, // SDL_SCANCODE_KP_COMMA ?
+    KeyboardKeys::None, // SDL_SCANCODE_KP_EQUALSAS400
+    KeyboardKeys::None, // SDL_SCANCODE_INTERNATIONAL1
+    KeyboardKeys::None, // SDL_SCANCODE_INTERNATIONAL2
+    KeyboardKeys::None, // SDL_SCANCODE_INTERNATIONAL3
+    KeyboardKeys::None, // SDL_SCANCODE_INTERNATIONAL4
+    KeyboardKeys::None, // SDL_SCANCODE_INTERNATIONAL5
+    KeyboardKeys::None, // SDL_SCANCODE_INTERNATIONAL6
+    KeyboardKeys::None, // SDL_SCANCODE_INTERNATIONAL7
+    KeyboardKeys::None, // SDL_SCANCODE_INTERNATIONAL8
+    KeyboardKeys::None, // SDL_SCANCODE_INTERNATIONAL9
+    KeyboardKeys::None, // SDL_SCANCODE_LANG1
+    KeyboardKeys::None, // SDL_SCANCODE_LANG2
+    KeyboardKeys::None, // SDL_SCANCODE_LANG3
+    KeyboardKeys::None, // SDL_SCANCODE_LANG4
+    KeyboardKeys::None, // SDL_SCANCODE_LANG5
+    KeyboardKeys::None, // SDL_SCANCODE_LANG6
+    KeyboardKeys::None, // SDL_SCANCODE_LANG7
+    KeyboardKeys::None, // SDL_SCANCODE_LANG8
+    KeyboardKeys::None, // SDL_SCANCODE_LANG9
+    KeyboardKeys::None, // SDL_SCANCODE_ALTERASE
+    KeyboardKeys::None, // SDL_SCANCODE_SYSREQ
+    KeyboardKeys::None, // SDL_SCANCODE_CANCEL
+    KeyboardKeys::Clear, // SDL_SCANCODE_CLEAR
+    KeyboardKeys::None, // SDL_SCANCODE_PRIOR
+    KeyboardKeys::None, // SDL_SCANCODE_RETURN2
+    KeyboardKeys::None, // SDL_SCANCODE_SEPARATOR
+    KeyboardKeys::None, // SDL_SCANCODE_OUT
+    KeyboardKeys::None, // SDL_SCANCODE_OPER
+    KeyboardKeys::None, // SDL_SCANCODE_CLEARAGAIN
+    KeyboardKeys::None, // SDL_SCANCODE_CRSEL
+    KeyboardKeys::None, // SDL_SCANCODE_EXSEL
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_00
+    KeyboardKeys::None, // SDL_SCANCODE_KP_000
+    KeyboardKeys::None, // SDL_SCANCODE_THOUSANDSSEPARATOR
+    KeyboardKeys::None, // SDL_SCANCODE_DECIMALSEPARATOR
+    KeyboardKeys::None, // SDL_SCANCODE_CURRENCYUNIT
+    KeyboardKeys::None, // SDL_SCANCODE_CURRENCYSUBUNIT
+    KeyboardKeys::None, // SDL_SCANCODE_KP_LEFTPAREN = 182,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_RIGHTPAREN = 183,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_LEFTBRACE = 184,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_RIGHTBRACE = 185,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_TAB = 186,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_BACKSPACE = 187,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_A = 188,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_B = 189,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_C = 190,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_D = 191,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_E = 192,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_F = 193,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_XOR = 194,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_POWER = 195,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_PERCENT = 196,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_LESS = 197,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_GREATER = 198,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_AMPERSAND = 199,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_DBLAMPERSAND = 200,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_VERTICALBAR = 201,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_DBLVERTICALBAR = 202,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_COLON = 203,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_HASH = 204,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_SPACE = 205,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_AT = 206,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_EXCLAM = 207,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_MEMSTORE = 208,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_MEMRECALL = 209,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_MEMCLEAR = 210,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_MEMADD = 211,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_MEMSUBTRACT = 212,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_MEMMULTIPLY = 213,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_MEMDIVIDE = 214,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_PLUSMINUS = 215,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_CLEAR = 216,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_CLEARENTRY = 217,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_BINARY = 218,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_OCTAL = 219,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_DECIMAL = 220,
+    KeyboardKeys::None, // SDL_SCANCODE_KP_HEXADECIMAL = 221,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::Control, // SDL_SCANCODE_LCTRL = 224,
+    KeyboardKeys::Shift, // SDL_SCANCODE_LSHIFT = 225,
+    KeyboardKeys::Alt, // SDL_SCANCODE_LALT = 226,
+    KeyboardKeys::LeftMenu, // SDL_SCANCODE_LGUI = 227,
+    KeyboardKeys::Control, // SDL_SCANCODE_RCTRL = 228,
+    KeyboardKeys::Shift, // SDL_SCANCODE_RSHIFT = 229,
+    KeyboardKeys::Alt, // SDL_SCANCODE_RALT = 230,
+    KeyboardKeys::RightMenu, // SDL_SCANCODE_RGUI = 231,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::None,
+    KeyboardKeys::Modechange, // SDL_SCANCODE_MODE
+    KeyboardKeys::Sleep, // SDL_SCANCODE_SLEEP
+    KeyboardKeys::None, // SDL_SCANCODE_WAKE
+    KeyboardKeys::None, // SDL_SCANCODE_CHANNEL_INCREMENT = 260,
+    KeyboardKeys::None, // SDL_SCANCODE_CHANNEL_DECREMENT = 261,
+    KeyboardKeys::None, // SDL_SCANCODE_MEDIA_PLAY = 262,
+    KeyboardKeys::None, // SDL_SCANCODE_MEDIA_PAUSE = 263,
+    KeyboardKeys::None, // SDL_SCANCODE_MEDIA_RECORD = 264,
+    KeyboardKeys::None, // SDL_SCANCODE_MEDIA_FAST_FORWARD = 265,
+    KeyboardKeys::None, // SDL_SCANCODE_MEDIA_REWIND = 266,
+    KeyboardKeys::MediaNextTrack, // SDL_SCANCODE_MEDIA_NEXT_TRACK = 267,
+    KeyboardKeys::MediaPrevTrack, // SDL_SCANCODE_MEDIA_PREVIOUS_TRACK = 268,
+    KeyboardKeys::MediaStop, // SDL_SCANCODE_MEDIA_STOP = 269,
+    KeyboardKeys::None, // SDL_SCANCODE_MEDIA_EJECT = 270,
+    KeyboardKeys::MediaPlayPause, // SDL_SCANCODE_MEDIA_PLAY_PAUSE = 271,
+    KeyboardKeys::None, // SDL_SCANCODE_MEDIA_SELECT = 272,
+    KeyboardKeys::None, // SDL_SCANCODE_AC_NEW = 273,
+    KeyboardKeys::None, // SDL_SCANCODE_AC_OPEN = 274,
+    KeyboardKeys::None, // SDL_SCANCODE_AC_CLOSE = 275,
+    KeyboardKeys::None, // SDL_SCANCODE_AC_EXIT = 276,
+    KeyboardKeys::None, // SDL_SCANCODE_AC_SAVE = 277,
+    KeyboardKeys::None, // SDL_SCANCODE_AC_PRINT = 278,
+    KeyboardKeys::None, // SDL_SCANCODE_AC_PROPERTIES = 279,
+    KeyboardKeys::None, // SDL_SCANCODE_AC_SEARCH = 280,
+    KeyboardKeys::None, // SDL_SCANCODE_AC_HOME = 281,
+    KeyboardKeys::None, // SDL_SCANCODE_AC_BACK = 282,
+    KeyboardKeys::None, // SDL_SCANCODE_AC_FORWARD = 283,
+    KeyboardKeys::None, // SDL_SCANCODE_AC_STOP = 284,
+    KeyboardKeys::None, // SDL_SCANCODE_AC_REFRESH = 285,
+    KeyboardKeys::None, // SDL_SCANCODE_AC_BOOKMARKS = 286,
+    KeyboardKeys::None, // SDL_SCANCODE_SOFTLEFT = 287,
+    KeyboardKeys::None, // SDL_SCANCODE_SOFTRIGHT = 288,
+    KeyboardKeys::None, // SDL_SCANCODE_CALL = 289,
+    KeyboardKeys::None, // SDL_SCANCODE_ENDCALL = 290
+};
+
+/// <summary>
+/// Implementation of the keyboard device for Windows platform.
+/// </summary>
+/// <seealso cref="Keyboard" />
+class SDLKeyboard : public Keyboard
+{
+public:
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="SDLKeyboard"/> class.
+    /// </summary>
+    explicit SDLKeyboard()
+        : Keyboard()
+    {
+    }
+
+public:
+
+};
+
+/// <summary>
+/// Implementation of the mouse device for SDL platform.
+/// </summary>
+/// <seealso cref="Mouse" />
+class SDLMouse : public Mouse
+{
+private:
+    Float2 oldPosition;
+public:
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="SDLMouse"/> class.
+    /// </summary>
+    explicit SDLMouse()
+        : Mouse()
+    {
+    }
+
+public:
+
+    /// <summary>
+    /// Returns the previous known position of the mouse before entering relative mode.
+    /// </summary>
+    Float2 GetOldMousePosition() const
+    {
+        return oldPosition;
+    }
+
+    // [Mouse]
+    void SetMousePosition(const Float2& newPosition) final override
+    {
+        SDL_WarpMouseGlobal(newPosition.X, newPosition.Y);
+        
+        OnMouseMoved(newPosition);
+    }
+
+    void SetRelativeMode(bool relativeMode, Window* window) final override
+    {
+        if (relativeMode == _relativeMode)
+            return;
+
+        if (relativeMode)
+            SDL_GetGlobalMouseState(&oldPosition.X, &oldPosition.Y);
+
+        Mouse::SetRelativeMode(relativeMode, window);
+        if (!SDL_SetWindowRelativeMouseMode(static_cast<SDLWindow*>(window)->_window, relativeMode))
+            LOG(Error, "Failed to set mouse relative mode: {0}", String(SDL_GetError()));
+
+        if (!relativeMode)
+            SetMousePosition(oldPosition);
+    }
+};
+
+/// <summary>
+/// Implementation of the gamepad device for SDL platform.
+/// </summary>
+/// <seealso cref="Gamepad" />
+class SDLGamepad : public Gamepad
+{
+private:
+
+    SDL_Gamepad* _gamepad;
+    SDL_JoystickID _instanceId;
+
+public:
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="SDLGamepad"/> class.
+    /// </summary>
+    /// <param name="userIndex">The joystick.</param>
+    explicit SDLGamepad(SDL_JoystickID instanceId);
+
+    /// <summary>
+    /// Finalizes an instance of the <see cref="SDLGamepad"/> class.
+    /// </summary>
+    ~SDLGamepad();
+
+private:
+
+    SDLGamepad(SDL_Gamepad* gamepad, SDL_JoystickID instanceId);
+
+public:
+
+    static SDLGamepad* GetGamepadById(SDL_JoystickID id)
+    {
+        SDLGamepad* gamepad = nullptr;
+        SDLInputImpl::Gamepads.TryGet(id, gamepad);
+        return gamepad;
+    }
+
+    SDL_JoystickID GetJoystickInstanceId() const
+    {
+        return _instanceId;
+    }
+
+    void OnAxisMotion(SDL_GamepadAxis axis, int16 value);
+
+    void OnButtonState(SDL_GamepadButton axis, bool pressed);
+
+    // [Gamepad]
+    void SetVibration(const GamepadVibrationState& state) override;
+
+protected:
+
+    // [Gamepad]
+    bool UpdateState() override;
+};
+
+void SDLInput::Init()
+{
+    Input::Mouse = SDLInputImpl::Mouse = New<SDLMouse>();
+    Input::Keyboard = SDLInputImpl::Keyboard = New<SDLKeyboard>();
+}
+
+void SDLInput::Update()
+{
+}
+
+float NormalizeAxisValue(const int16 axisVal)
+{
+    // Normalize [-32768..32767] -> [-1..1]
+    const float norm = axisVal <= 0 ? 32768.0f : 32767.0f;
+    return float(axisVal) / norm;
+}
+
+bool SDLInput::HandleEvent(SDLWindow* window, SDL_Event& event)
+{
+    switch (event.type)
+    {
+    case SDL_EVENT_MOUSE_MOTION:
+    {
+        if (Input::Mouse->IsRelative())
+        {
+            const Float2 mouseDelta(event.motion.xrel, event.motion.yrel);
+            Input::Mouse->OnMouseMoveRelative(mouseDelta, window);
+        }
+        else
+        {
+            const Float2 mousePos = window->ClientToScreen({ event.motion.x, event.motion.y });
+            Int2 p;
+            Float2 wp = window->ClientToScreen({0, 0});
+            //SDL_GetWindowPosition(window->GetSDLWindow(), &p.X, &p.Y);
+            p.X = wp.X;
+            p.Y = wp.Y;
+            //LOG(Info, "motion {},{}, mouse: {}, win: {}, winpos {},{}", event.motion.x, event.motion.y, mousePos, String(window->GetTitle()), p.X, p.Y);
+            Input::Mouse->OnMouseMove(mousePos, window);
+        }
+        return true;
+    }
+    case SDL_EVENT_WINDOW_MOUSE_LEAVE:
+    {
+        Input::Mouse->OnMouseLeave(window);
+        return true;
+    }
+    case SDL_EVENT_MOUSE_BUTTON_DOWN:
+    case SDL_EVENT_MOUSE_BUTTON_UP:
+    {
+        Float2 mousePos = window->ClientToScreen({ event.button.x, event.button.y });
+        MouseButton button = MouseButton::None;
+        if (event.button.button == SDL_BUTTON_LEFT)
+            button = MouseButton::Left;
+        else if (event.button.button == SDL_BUTTON_RIGHT)
+            button = MouseButton::Right;
+        else if (event.button.button == SDL_BUTTON_MIDDLE)
+            button = MouseButton::Middle;
+        else if (event.button.button == SDL_BUTTON_X1)
+            button = MouseButton::Extended1;
+        else if (event.button.button == SDL_BUTTON_X2)
+            button = MouseButton::Extended2;
+
+        if (Input::Mouse->IsRelative())
+        {
+            // Use the previous visible mouse position here, the event or global
+            // mouse position would cause input to trigger in other editor windows.
+            mousePos = SDLInputImpl::Mouse->GetOldMousePosition();
+        }
+
+        if (!event.button.down)
+            Input::Mouse->OnMouseUp(mousePos, button, window);
+        // Prevent sending multiple mouse down event when double-clicking UI elements
+        else if (event.button.clicks % 2 == 1)
+            Input::Mouse->OnMouseDown(mousePos, button, window);
+        else
+            Input::Mouse->OnMouseDoubleClick(mousePos, button, window);
+
+        return true;
+    }
+    case SDL_EVENT_MOUSE_WHEEL:
+    {
+        Float2 mousePos = window->ClientToScreen({ event.wheel.mouse_x, event.wheel.mouse_y });
+        const float delta = event.wheel.y;
+
+        if (Input::Mouse->IsRelative())
+        {
+            // Use the previous visible mouse position here, the event or global
+            // mouse position would cause input to trigger in other editor windows.
+            mousePos = SDLInputImpl::Mouse->GetOldMousePosition();
+        }
+
+        Input::Mouse->OnMouseWheel(mousePos, delta, window);
+        return true;
+    }
+    case SDL_EVENT_KEY_DOWN:
+    case SDL_EVENT_KEY_UP:
+    {
+        // TODO: scancode support
+        KeyboardKeys key = SDL_TO_FLAX_KEYS_MAP[event.key.scancode];
+        //event.key.mod
+        if (!event.key.down)
+            Input::Keyboard->OnKeyUp(key, window);
+        else
+            Input::Keyboard->OnKeyDown(key, window);
+        return true;
+    }
+    case SDL_EVENT_TEXT_EDITING:
+    {
+        auto edit = event.edit;
+        return true;
+    }
+    case SDL_EVENT_TEXT_INPUT:
+    {
+        String text(event.text.text);
+        for (int i = 0; i < text.Length(); i++)
+        {
+            Input::Keyboard->OnCharInput(text[i], window);
+        }
+        return true;
+    }
+    case SDL_EVENT_GAMEPAD_AXIS_MOTION:
+    {
+        SDLGamepad* gamepad = SDLGamepad::GetGamepadById(event.gaxis.which);
+        SDL_GamepadAxis axis = (SDL_GamepadAxis)event.gaxis.axis;
+        gamepad->OnAxisMotion(axis, event.gaxis.value);
+
+        LOG(Info, "SDL_EVENT_GAMEPAD_AXIS_MOTION");
+        break;
+    }
+    case SDL_EVENT_GAMEPAD_BUTTON_DOWN:
+    case SDL_EVENT_GAMEPAD_BUTTON_UP:
+    {
+        SDLGamepad* gamepad = SDLGamepad::GetGamepadById(event.gbutton.which);
+        SDL_GamepadButton button = (SDL_GamepadButton)event.gbutton.button;
+        gamepad->OnButtonState(button, event.gbutton.down);
+
+        LOG(Info, "SDL_EVENT_GAMEPAD_BUTTON_");
+        break;
+    }
+    case SDL_EVENT_GAMEPAD_ADDED:
+    {
+        Input::Gamepads.Add(New<SDLGamepad>(event.gdevice.which));
+        Input::OnGamepadsChanged();
+
+        LOG(Info, "SDL_EVENT_GAMEPAD_ADDED");
+        break;
+    }
+    case SDL_EVENT_GAMEPAD_REMOVED:
+    {
+        for (int i = 0; i < Input::Gamepads.Count(); i++)
+        {
+            SDLGamepad* gamepad = static_cast<SDLGamepad*>(Input::Gamepads[i]);
+            if (gamepad->GetJoystickInstanceId() == event.gdevice.which)
+            {
+                Input::Gamepads[i]->DeleteObject();
+                Input::Gamepads.RemoveAtKeepOrder(i);
+                Input::OnGamepadsChanged();
+                break;
+            }
+        }
+        
+        LOG(Info, "SDL_EVENT_GAMEPAD_REMOVED");
+        break;
+    }
+    case SDL_EVENT_GAMEPAD_REMAPPED:
+    {
+        auto ev = event.gdevice;
+        LOG(Info, "SDL_EVENT_GAMEPAD_REMAPPED");
+        break;
+    }
+    case SDL_EVENT_GAMEPAD_TOUCHPAD_DOWN:
+    {
+        LOG(Info, "SDL_EVENT_GAMEPAD_TOUCHPAD_DOWN");
+        break;
+    }
+    case SDL_EVENT_GAMEPAD_TOUCHPAD_MOTION:
+    {
+        LOG(Info, "SDL_EVENT_GAMEPAD_TOUCHPAD_MOTION");
+        break;
+    }
+    case SDL_EVENT_GAMEPAD_TOUCHPAD_UP:
+    {
+        LOG(Info, "SDL_EVENT_GAMEPAD_TOUCHPAD_UP");
+        break;
+    }
+    case SDL_EVENT_GAMEPAD_SENSOR_UPDATE:
+    {
+        LOG(Info, "SDL_EVENT_GAMEPAD_SENSOR_UPDATE");
+        break;
+    }
+    case SDL_EVENT_GAMEPAD_STEAM_HANDLE_UPDATED:
+    {
+        auto ev = event.gdevice;
+        LOG(Info, "SDL_EVENT_GAMEPAD_STEAM_HANDLE_UPDATED");
+        break;
+    }
+    }
+    return false;
+}
+
+Guid GetGamepadGuid(SDL_JoystickID instanceId)
+{
+    SDL_GUID joystickGuid = SDL_GetGamepadGUIDForID(instanceId);
+    Guid guid;
+    Platform::MemoryCopy(&guid.Raw, joystickGuid.data, sizeof(uint8) * 16);
+    return guid;
+}
+
+SDLGamepad::SDLGamepad(SDL_JoystickID instanceId)
+    : SDLGamepad(SDL_OpenGamepad(instanceId), instanceId)
+{
+}
+
+SDLGamepad::SDLGamepad(SDL_Gamepad* gamepad, SDL_JoystickID instanceId)
+    : Gamepad(GetGamepadGuid(instanceId), String(SDL_GetGamepadName(gamepad)))
+    , _gamepad(gamepad)
+    , _instanceId(instanceId)
+{
+    SDLInputImpl::Gamepads.Add(_instanceId, this);
+}
+
+SDLGamepad::~SDLGamepad()
+{
+    SDL_CloseGamepad(_gamepad);
+    SDLInputImpl::Gamepads.Remove(_instanceId);
+}
+
+void SDLGamepad::SetVibration(const GamepadVibrationState& state)
+{
+    Gamepad::SetVibration(state);
+}
+
+bool SDLGamepad::UpdateState()
+{
+    return false;
+}
+
+void SDLGamepad::OnAxisMotion(SDL_GamepadAxis sdlAxis, int16 value)
+{
+    GamepadAxis axis;
+    int16 deadzone = 1; // SDL reports -1 for centered axis?
+    float valueNormalized = NormalizeAxisValue(value);
+    switch (sdlAxis)
+    {
+    case SDL_GAMEPAD_AXIS_LEFTX:
+        axis = GamepadAxis::LeftStickX;
+        deadzone = LEFT_STICK_THRESHOLD;
+        _state.Buttons[(int32)GamepadButton::LeftStickLeft] = value > LEFT_STICK_THRESHOLD;
+        _state.Buttons[(int32)GamepadButton::LeftStickRight] = value < -LEFT_STICK_THRESHOLD;
+        break;
+    case SDL_GAMEPAD_AXIS_LEFTY:
+        axis = GamepadAxis::LeftStickY;
+        deadzone = LEFT_STICK_THRESHOLD;
+        _state.Buttons[(int32)GamepadButton::LeftStickUp] = value < -LEFT_STICK_THRESHOLD;
+        _state.Buttons[(int32)GamepadButton::LeftStickDown] = value > LEFT_STICK_THRESHOLD;
+        valueNormalized = -valueNormalized;
+        break;
+    case SDL_GAMEPAD_AXIS_RIGHTX:
+        deadzone = RIGHT_STICK_THRESHOLD;
+        axis = GamepadAxis::RightStickX;
+        _state.Buttons[(int32)GamepadButton::RightStickLeft] = value > RIGHT_STICK_THRESHOLD;
+        _state.Buttons[(int32)GamepadButton::RightStickRight] = value < -RIGHT_STICK_THRESHOLD;
+        break;
+    case SDL_GAMEPAD_AXIS_RIGHTY:
+        deadzone = RIGHT_STICK_THRESHOLD;
+        axis = GamepadAxis::RightStickY;
+        _state.Buttons[(int32)GamepadButton::RightStickUp] = value < -RIGHT_STICK_THRESHOLD;
+        _state.Buttons[(int32)GamepadButton::RightStickDown] = value > RIGHT_STICK_THRESHOLD;
+        valueNormalized = -valueNormalized;
+        break;
+    case SDL_GAMEPAD_AXIS_LEFT_TRIGGER:
+        deadzone = TRIGGER_THRESHOLD;
+        axis = GamepadAxis::LeftTrigger;
+        _state.Buttons[(int32)GamepadButton::LeftTrigger] = value > TRIGGER_THRESHOLD;
+        break;
+    case SDL_GAMEPAD_AXIS_RIGHT_TRIGGER:
+        deadzone = TRIGGER_THRESHOLD;
+        axis = GamepadAxis::RightTrigger;
+        _state.Buttons[(int32)GamepadButton::RightTrigger] = value > TRIGGER_THRESHOLD;
+        break;
+    default:
+        return;
+    }
+    if (value <= deadzone && value >= -deadzone)
+        valueNormalized = 0.0f;
+    _state.Axis[(int32)axis] = valueNormalized;
+}
+
+void SDLGamepad::OnButtonState(SDL_GamepadButton sdlButton, bool pressed)
+{
+    switch (sdlButton)
+    {
+    case SDL_GamepadButton::SDL_GAMEPAD_BUTTON_SOUTH:
+        _state.Buttons[(int32)GamepadButton::A] = pressed;
+        break;
+    case SDL_GamepadButton::SDL_GAMEPAD_BUTTON_EAST:
+        _state.Buttons[(int32)GamepadButton::B] = pressed;
+        break;
+    case SDL_GamepadButton::SDL_GAMEPAD_BUTTON_WEST:
+        _state.Buttons[(int32)GamepadButton::X] = pressed;
+        break;
+    case SDL_GamepadButton::SDL_GAMEPAD_BUTTON_NORTH:
+        _state.Buttons[(int32)GamepadButton::Y] = pressed;
+        break;
+    case SDL_GamepadButton::SDL_GAMEPAD_BUTTON_LEFT_SHOULDER:
+        _state.Buttons[(int32)GamepadButton::LeftShoulder] = pressed;
+        break;
+    case SDL_GamepadButton::SDL_GAMEPAD_BUTTON_RIGHT_SHOULDER:
+        _state.Buttons[(int32)GamepadButton::RightShoulder] = pressed;
+        break;
+    case SDL_GamepadButton::SDL_GAMEPAD_BUTTON_BACK:
+        _state.Buttons[(int32)GamepadButton::Back] = pressed;
+        break;
+    case SDL_GamepadButton::SDL_GAMEPAD_BUTTON_START:
+        _state.Buttons[(int32)GamepadButton::Start] = pressed;
+        break;
+    case SDL_GamepadButton::SDL_GAMEPAD_BUTTON_LEFT_STICK:
+        _state.Buttons[(int32)GamepadButton::LeftThumb] = pressed;
+        break;
+    case SDL_GamepadButton::SDL_GAMEPAD_BUTTON_RIGHT_STICK:
+        _state.Buttons[(int32)GamepadButton::RightThumb] = pressed;
+        break;
+    case SDL_GamepadButton::SDL_GAMEPAD_BUTTON_DPAD_UP:
+        _state.Buttons[(int32)GamepadButton::DPadUp] = pressed;
+        break;
+    case SDL_GamepadButton::SDL_GAMEPAD_BUTTON_DPAD_DOWN:
+        _state.Buttons[(int32)GamepadButton::DPadDown] = pressed;
+        break;
+    case SDL_GamepadButton::SDL_GAMEPAD_BUTTON_DPAD_LEFT:
+        _state.Buttons[(int32)GamepadButton::DPadLeft] = pressed;
+        break;
+    case SDL_GamepadButton::SDL_GAMEPAD_BUTTON_DPAD_RIGHT:
+        _state.Buttons[(int32)GamepadButton::DPadRight] = pressed;
+        break;
+    }
+}
+
+#endif

Source/Engine/Platform/SDL/SDLInput.h

@@ -0,0 +1,22 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#if PLATFORM_SDL
+
+class SDLWindow;
+union SDL_Event;
+
+/// <summary>
+/// SDL specific implementation of the input system parts.
+/// </summary>
+class SDLInput
+{
+public:
+
+    static void Init();
+    static void Update();
+    static bool HandleEvent(SDLWindow* window, SDL_Event& event);
+};
+
+#endif

Source/Engine/Platform/SDL/SDLPlatform.Linux.cpp

@@ -0,0 +1,937 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+#if PLATFORM_SDL && PLATFORM_LINUX
+
+#include "Engine/Platform/Platform.h"
+#include "SDLWindow.h"
+#include "Engine/Platform/IGuiData.h"
+#include "Engine/Engine/Engine.h"
+#include "Engine/Platform/SDL/SDLClipboard.h"
+#include "Engine/Profiler/ProfilerCPU.h"
+#include "Engine/Core/Log.h"
+#include "Engine/Core/Collections/Array.h"
+#include "Engine/Engine/CommandLine.h"
+#include "Engine/Platform/WindowsManager.h"
+#include "Engine/Platform/Linux/IncludeX11.h"
+
+#include <SDL3/SDL_video.h>
+#include <SDL3/SDL_system.h>
+#include <SDL3/SDL_hints.h>
+#include <SDL3/SDL_timer.h>
+
+Delegate<void*> LinuxPlatform::xEventReceived;
+
+// Missing Wayland features:
+// - Application icon (xdg-toplevel-icon-v1) https://github.com/libsdl-org/SDL/pull/9584
+// - Window positioning and position tracking
+// - Color picker (xdg-desktop-portal?) https://flatpak.github.io/xdg-desktop-portal/docs/doc-org.freedesktop.portal.Screenshot.html
+// - 
+
+namespace
+{
+    bool UseWayland = false;
+    bool UseXWayland = false;
+    X11::Display* xDisplay = nullptr;
+    X11::XIM IM = nullptr;
+    X11::XIC IC = nullptr;
+    X11::Atom xAtomDeleteWindow;
+    X11::Atom xAtomXdndEnter;
+    X11::Atom xAtomXdndPosition;
+    X11::Atom xAtomXdndLeave;
+    X11::Atom xAtomXdndDrop;
+    X11::Atom xAtomXdndActionCopy;
+    X11::Atom xAtomXdndStatus;
+    X11::Atom xAtomXdndSelection;
+    X11::Atom xAtomXdndFinished;
+    X11::Atom xAtomXdndAware;
+    X11::Atom xAtomWmState;
+    X11::Atom xAtomWmStateHidden;
+    X11::Atom xAtomWmStateMaxVert;
+    X11::Atom xAtomWmStateMaxHorz;
+    X11::Atom xAtomWmWindowOpacity;
+    X11::Atom xAtomWmName;
+    X11::Atom xAtomAtom;
+    X11::Atom xAtomClipboard;
+    X11::Atom xAtomPrimary;
+    X11::Atom xAtomTargets;
+    X11::Atom xAtomText;
+    X11::Atom xAtomString;
+    X11::Atom xAtomUTF8String;
+    X11::Atom xAtomXselData;
+    
+    X11::Atom xDnDRequested = 0;
+    X11::Window xDndSourceWindow = 0;
+    DragDropEffect xDndResult;
+    Float2 xDndPos;
+    int32 xDnDVersion = 0;
+    int32 XFixesSelectionNotifyEvent = 0;
+}
+
+class LinuxDropFilesData : public IGuiData
+{
+public:
+    Array<String> Files;
+
+    Type GetType() const override
+    {
+        return Type::Files;
+    }
+    String GetAsText() const override
+    {
+        return String::Empty;
+    }
+    void GetAsFiles(Array<String>* files) const override
+    {
+        files->Add(Files);
+    }
+};
+
+class LinuxDropTextData : public IGuiData
+{
+public:
+    StringView Text;
+
+    Type GetType() const override
+    {
+        return Type::Text;
+    }
+    String GetAsText() const override
+    {
+        return String(Text);
+    }
+    void GetAsFiles(Array<String>* files) const override
+    {
+    }
+};
+
+struct Property
+{
+    unsigned char* data;
+    int format, nitems;
+    X11::Atom type;
+};
+
+namespace Impl
+{
+    StringAnsi ClipboardText;
+    
+    void ClipboardGetText(String& result, X11::Atom source, X11::Atom atom, X11::Window window)
+    {
+        X11::Window selectionOwner = X11::XGetSelectionOwner(xDisplay, source);
+        if (selectionOwner == 0)
+        {
+            // No copy owner
+            return;
+        }
+        if (selectionOwner == window)
+        {
+            // Copy/paste from self
+            result.Set(ClipboardText.Get(), ClipboardText.Length());
+            return;
+        }
+
+        // Send event to get data from the owner
+        int format;
+        unsigned long N, size;
+        char* data;
+        X11::Atom target;
+        X11::XEvent event;
+        X11::XConvertSelection(xDisplay, xAtomClipboard, atom, xAtomXselData, window, CurrentTime);
+        X11::XSync(xDisplay, 0);
+        if (X11::XCheckTypedEvent(xDisplay, SelectionNotify, &event))
+        {
+            if (event.xselection.selection != xAtomClipboard)
+                return;
+            if (event.xselection.property)
+            {
+                X11::XGetWindowProperty(event.xselection.display, event.xselection.requestor, event.xselection.property, 0L,(~0L), 0, AnyPropertyType, &target, &format, &size, &N,(unsigned char**)&data);
+                if (target == xAtomUTF8String || target == xAtomString)
+                {
+                    // Got text to paste
+                    result.Set(data , size);
+                    X11::XFree(data);
+                }
+                X11::XDeleteProperty(event.xselection.display, event.xselection.requestor, event.xselection.property);
+            }
+        }
+    }
+    
+    Property ReadProperty(X11::Display* display, X11::Window window, X11::Atom property)
+    {
+        X11::Atom readType = 0;
+        int readFormat = 0;
+        unsigned long nitems = 0;
+        unsigned long readBytes = 0;
+        unsigned char* result = nullptr;
+        int bytesCount = 1024;
+        if (property != 0)
+        {
+            do
+            {
+                if (result != nullptr)
+                    X11::XFree(result);
+                XGetWindowProperty(display, window, property, 0, bytesCount, 0, AnyPropertyType, &readType, &readFormat, &nitems, &readBytes, &result);
+                bytesCount *= 2;
+            } while (readBytes != 0);
+        }
+        Property p = { result, readFormat, (int)nitems, readType };
+        return p;
+    }
+
+    static X11::Atom SelectTargetFromList(X11::Display* display, const char* targetType, X11::Atom* list, int count)
+    {
+        for (int i = 0; i < count; i++)
+        {
+            X11::Atom atom = list[i];
+            if (atom != 0 && StringAnsi(XGetAtomName(display, atom)) == targetType)
+                return atom;
+        }
+        return 0;
+    }
+
+    static X11::Atom SelectTargetFromAtoms(X11::Display* display, const char* targetType, X11::Atom t1, X11::Atom t2, X11::Atom t3)
+    {
+        if (t1 != 0 && StringAnsi(XGetAtomName(display, t1)) == targetType)
+            return t1;
+        if (t2 != 0 && StringAnsi(XGetAtomName(display, t2)) == targetType)
+            return t2;
+        if (t3 != 0 && StringAnsi(XGetAtomName(display, t3)) == targetType)
+            return t3;
+        return 0;
+    }
+
+    static X11::Window FindAppWindow(X11::Display* display, X11::Window w)
+    {
+        int nprops, i = 0;
+        X11::Atom* a;
+        if (w == 0)
+            return 0;
+        a = X11::XListProperties(display, w, &nprops);
+        for (i = 0; i < nprops; i++)
+        {
+            if (a[i] == xAtomXdndAware)
+                break;
+        }
+        if (nprops)
+            X11::XFree(a);
+        if (i != nprops)
+            return w;
+        X11::Window child, wtmp;
+        int tmp;
+        unsigned int utmp;
+        X11::XQueryPointer(display, w, &wtmp, &child, &tmp, &tmp, &tmp, &tmp, &utmp);
+        return FindAppWindow(display, child);
+    }
+
+    static Float2 GetX11MousePosition()
+    {
+        if (!xDisplay)
+            return Float2::Zero;
+        int32 x = 0, y = 0;
+        uint32 screenCount = (uint32)X11::XScreenCount(xDisplay);
+        for (uint32 i = 0; i < screenCount; i++)
+        {
+            X11::Window outRoot, outChild;
+            int32 childX, childY;
+            uint32 mask;
+            if (X11::XQueryPointer(xDisplay, X11::XRootWindow(xDisplay, i), &outRoot, &outChild, &x, &y, &childX, &childY, &mask))
+                break;
+        }
+        return Float2((float)x, (float)y);
+    }
+}
+
+DragDropEffect Window::DoDragDrop(const StringView& data)
+{
+    if (CommandLine::Options.Headless)
+        return DragDropEffect::None;
+
+    if (UseWayland)
+        return DoDragDropWayland(data);
+    else
+        return DoDragDropX11(data);
+}
+
+DragDropEffect Window::DoDragDropWayland(const StringView& data)
+{
+    // TODO: Wayland
+    LOG(Warning, "Wayland Drag and drop is not implemented yet.");
+    return DragDropEffect::None;
+}
+
+DragDropEffect Window::DoDragDropX11(const StringView& data)
+{
+	auto cursorWrong = X11::XCreateFontCursor(xDisplay, 54);
+	auto cursorTransient = X11::XCreateFontCursor(xDisplay, 24);
+	auto cursorGood = X11::XCreateFontCursor(xDisplay, 4);
+    Array<X11::Atom, FixedAllocation<3>> formats;
+    formats.Add(X11::XInternAtom(xDisplay, "text/plain", 0));
+    formats.Add(xAtomText);
+    formats.Add(xAtomString);
+    StringAnsi dataAnsi(data);
+    LinuxDropTextData dropData;
+    dropData.Text = data;
+#if !PLATFORM_SDL
+    X11::Window mainWindow = _window;
+#else
+    X11::Window mainWindow = static_cast<X11::Window>(GetX11WindowHandle());
+#endif
+
+    // Make sure SDL hasn't grabbed the pointer, and force ungrab it
+    XUngrabPointer(xDisplay, CurrentTime);
+    SDL_SetHint(SDL_HINT_MOUSE_AUTO_CAPTURE, "0");
+
+    // Begin dragging
+	auto screen = X11::XDefaultScreen(xDisplay);
+	auto rootWindow = X11::XRootWindow(xDisplay, screen);
+
+    if (X11::XGrabPointer(xDisplay, mainWindow, 1, Button1MotionMask | ButtonReleaseMask, GrabModeAsync, GrabModeAsync, rootWindow, cursorWrong, CurrentTime) != GrabSuccess)
+    {
+        SDL_SetHint(SDL_HINT_MOUSE_AUTO_CAPTURE, "1");
+        return DragDropEffect::None;
+    }
+    X11::XSetSelectionOwner(xDisplay, xAtomXdndSelection, mainWindow, CurrentTime);
+
+    // Process events
+    X11::XEvent event;
+    enum Status
+    {
+        Unaware,
+        Unreceptive,
+        CanDrop,
+    };
+    int status = Unaware, previousVersion = -1;
+    X11::Window previousWindow = 0;
+    DragDropEffect result = DragDropEffect::None;
+    float lastDraw = Platform::GetTimeSeconds();
+    float startTime = lastDraw;
+    while (true)
+    {
+        X11::XNextEvent(xDisplay, &event);
+
+        if (event.type == SelectionClear)
+            break;
+        if (event.type == SelectionRequest)
+        {
+            // Extract the relavent data
+            X11::Window owner = event.xselectionrequest.owner;
+            X11::Atom selection = event.xselectionrequest.selection;
+            X11::Atom target = event.xselectionrequest.target;
+            X11::Atom property = event.xselectionrequest.property;
+            X11::Window requestor = event.xselectionrequest.requestor;
+            X11::Time timestamp = event.xselectionrequest.time;
+            X11::Display* disp = event.xselection.display;
+            X11::XEvent s;
+            s.xselection.type = SelectionNotify;
+            s.xselection.requestor = requestor;
+            s.xselection.selection = selection;
+            s.xselection.target = target;
+            s.xselection.property = 0;
+            s.xselection.time = timestamp;
+            if (target == xAtomTargets)
+            {
+                Array<X11::Atom> targets;
+                targets.Add(target);
+                targets.Add(X11::XInternAtom(disp, "MULTIPLE", 0));
+                targets.Add(formats.Get(), formats.Count());
+                X11::XChangeProperty(disp, requestor, property, xAtomAtom, 32, PropModeReplace, (unsigned char*)targets.Get(), targets.Count());
+                s.xselection.property = property;
+            }
+            else if (formats.Contains(target))
+            {
+                s.xselection.property = property;
+                X11::XChangeProperty(disp, requestor, property, target, 8, PropModeReplace, reinterpret_cast<const unsigned char*>(dataAnsi.Get()), dataAnsi.Length());
+            }
+            X11::XSendEvent(event.xselection.display, event.xselectionrequest.requestor, 1, 0, &s);
+        }
+        else if (event.type == MotionNotify)
+        {
+            // Find window under mouse
+            auto window = Impl::FindAppWindow(xDisplay, rootWindow);
+			int fmt, version = -1;
+			X11::Atom atmp;
+			unsigned long nitems, bytesLeft;
+			unsigned char* data = nullptr;
+            if (window == previousWindow)
+                version = previousVersion;
+            else if(window == 0)
+                ;
+            else if (X11::XGetWindowProperty(xDisplay, window, xAtomXdndAware, 0, 2, 0, AnyPropertyType, &atmp, &fmt, &nitems, &bytesLeft, &data) != Success)
+                continue;
+            else if (data == 0)
+                continue;
+            else if (fmt != 32)
+                continue;
+            else if (nitems != 1)
+                continue;
+            else
+				version = data[0];
+            if (status == Unaware && version != -1)
+            	status = Unreceptive;
+            else if(version == -1)
+            	status = Unaware;
+            xDndPos = Float2((float)event.xmotion.x_root, (float)event.xmotion.y_root);
+
+            // Update mouse grab
+            if (status == Unaware)
+                X11::XChangeActivePointerGrab(xDisplay, Button1MotionMask | ButtonReleaseMask, cursorWrong, CurrentTime);
+            else if(status == Unreceptive)
+                X11::XChangeActivePointerGrab(xDisplay, Button1MotionMask | ButtonReleaseMask, cursorTransient, CurrentTime);
+            else
+                X11::XChangeActivePointerGrab(xDisplay, Button1MotionMask | ButtonReleaseMask, cursorGood, CurrentTime);
+
+            if (window != previousWindow && previousVersion != -1)
+            {
+                // Send drag left event
+                auto ww = WindowsManager::GetByNativePtr((void*)previousWindow);
+                if (ww)
+                {
+                    ww->_dragOver = false;
+                    ww->OnDragLeave();
+                }
+                else
+                {
+                    X11::XClientMessageEvent m;
+                    memset(&m, 0, sizeof(m));
+                    m.type = ClientMessage;
+                    m.display = event.xclient.display;
+                    m.window = previousWindow;
+                    m.message_type = xAtomXdndLeave;
+                    m.format = 32;
+                    m.data.l[0] = mainWindow;
+                    m.data.l[1] = 0;
+                    m.data.l[2] = 0;
+                    m.data.l[3] = 0;
+                    m.data.l[4] = 0;
+                    X11::XSendEvent(xDisplay, previousWindow, 0, NoEventMask, (X11::XEvent*)&m);
+                    X11::XFlush(xDisplay);
+                }
+            }
+
+            if (window != previousWindow && version != -1)
+            {
+                // Send drag enter event
+                auto ww = WindowsManager::GetByNativePtr((void*)window);
+                if (ww)
+                {
+                    xDndPos = ww->ScreenToClient(Impl::GetX11MousePosition());
+                    xDndResult = DragDropEffect::None;
+                    ww->OnDragEnter(&dropData, xDndPos, xDndResult);
+                }
+                else
+                {
+                    X11::XClientMessageEvent m;
+                    memset(&m, 0, sizeof(m));
+                    m.type = ClientMessage;
+                    m.display = event.xclient.display;
+                    m.window = window;
+                    m.message_type = xAtomXdndEnter;
+                    m.format = 32;
+                    m.data.l[0] = mainWindow;
+                    m.data.l[1] = Math::Min(5, version) << 24  | (formats.Count() > 3);
+                    m.data.l[2] = formats.Count() > 0 ? formats[0] : 0;
+                    m.data.l[3] = formats.Count() > 1 ? formats[1] : 0;
+                    m.data.l[4] = formats.Count() > 2 ? formats[2] : 0;
+                    X11::XSendEvent(xDisplay, window, 0, NoEventMask, (X11::XEvent*)&m);
+                    X11::XFlush(xDisplay);
+                }
+            }
+
+            if (version != -1)
+            {
+                // Send position event
+                auto ww = WindowsManager::GetByNativePtr((void*)window);
+                if (ww)
+                {
+                    xDndPos = ww->ScreenToClient(Impl::GetX11MousePosition());
+                    ww->_dragOver = true;
+                    xDndResult = DragDropEffect::None;
+                    ww->OnDragOver(&dropData, xDndPos, xDndResult);
+                    status = CanDrop;
+                }
+                else
+                {
+                    int x, y, tmp;
+                    unsigned int utmp;
+                    X11::Window wtmp;
+                    X11::XQueryPointer(xDisplay, window, &wtmp, &wtmp, &tmp, &tmp, &x, &y, &utmp);
+                    X11::XClientMessageEvent m;
+                    memset(&m, 0, sizeof(m));
+                    m.type = ClientMessage;
+                    m.display = event.xclient.display;
+                    m.window = window;
+                    m.message_type = xAtomXdndPosition;
+                    m.format = 32;
+                    m.data.l[0] = mainWindow;
+                    m.data.l[1] = 0;
+                    m.data.l[2] = (x << 16) | y;
+                    m.data.l[3] = CurrentTime;
+                    m.data.l[4] = xAtomXdndActionCopy;
+                    X11::XSendEvent(xDisplay, window, 0, NoEventMask, (X11::XEvent*)&m);
+                    X11::XFlush(xDisplay);
+                }
+            }
+
+            previousWindow = window;
+            previousVersion = version;
+        }
+        else if (event.type == ClientMessage && event.xclient.message_type == xAtomXdndStatus)
+        {
+            if ((event.xclient.data.l[1]&1) && status != Unaware)
+                status = CanDrop;
+            if (!(event.xclient.data.l[1]&1) && status != Unaware)
+                status = Unreceptive;
+        }
+        else if (event.type == ButtonRelease && event.xbutton.button == Button1)
+        {
+            if (status == CanDrop)
+            {
+                // Send drop event
+                auto ww = WindowsManager::GetByNativePtr((void*)previousWindow);
+                if (ww)
+                {
+                    xDndPos = ww->ScreenToClient(Impl::GetX11MousePosition());
+                    xDndResult = DragDropEffect::None;
+                    ww->OnDragDrop(&dropData, xDndPos, xDndResult);
+                    ww->Focus();
+					result = xDndResult;
+                }
+                else
+                {
+                    X11::XClientMessageEvent m;
+                    memset(&m, 0, sizeof(m));
+                    m.type = ClientMessage;
+                    m.display = event.xclient.display;
+                    m.window = previousWindow;
+                    m.message_type = xAtomXdndDrop;
+                    m.format = 32;
+                    m.data.l[0] = mainWindow;
+                    m.data.l[1] = 0;
+                    m.data.l[2] = CurrentTime;
+                    m.data.l[3] = 0;
+                    m.data.l[4] = 0;
+                    X11::XSendEvent(xDisplay, previousWindow, 0, NoEventMask, (X11::XEvent*)&m);
+                    X11::XFlush(xDisplay);
+                	result = DragDropEffect::Copy;
+                }
+            }
+            break;
+        }
+
+        // Redraw
+        const float time = Platform::GetTimeSeconds();
+        if (time - lastDraw >= 1.0f / 20.0f)
+        {
+            lastDraw = time;
+            
+            Engine::OnDraw();
+        }
+
+        // Prevent dead-loop
+        if (time - startTime >= 10.0f)
+        {
+            LOG(Warning, "DoDragDrop timed out after 10 seconds.");
+            break;
+        }
+    }
+
+    // Drag end
+    if (previousWindow != 0 && previousVersion != -1)
+    {
+        // Send drag left event
+        auto ww = WindowsManager::GetByNativePtr((void*)previousWindow);
+        if (ww)
+        {
+            ww->_dragOver = false;
+            ww->OnDragLeave();
+        }
+        else
+        {
+            X11::XClientMessageEvent m;
+            memset(&m, 0, sizeof(m));
+            m.type = ClientMessage;
+            m.display = event.xclient.display;
+            m.window = previousWindow;
+            m.message_type = xAtomXdndLeave;
+            m.format = 32;
+            m.data.l[0] = mainWindow;
+            m.data.l[1] = 0;
+            m.data.l[2] = 0;
+            m.data.l[3] = 0;
+            m.data.l[4] = 0;
+            X11::XSendEvent(xDisplay, previousWindow, 0, NoEventMask, (X11::XEvent*)&m);
+            X11::XFlush(xDisplay);
+        }
+    }
+
+    // End grabbing
+    X11::XChangeActivePointerGrab(xDisplay, Button1MotionMask | ButtonReleaseMask, 0, CurrentTime);
+    XUngrabPointer(xDisplay, CurrentTime);
+    X11::XFlush(xDisplay);
+
+    SDL_SetHint(SDL_HINT_MOUSE_AUTO_CAPTURE, "1");
+
+	return result;
+}
+
+void SDLClipboard::Clear()
+{
+    SetText(StringView::Empty);
+}
+
+void SDLClipboard::SetText(const StringView& text)
+{
+    if (CommandLine::Options.Headless)
+        return;
+    auto mainWindow = Engine::MainWindow;
+    if (!mainWindow)
+        return;
+
+    if (xDisplay)
+    {
+        X11::Window window = (X11::Window)(mainWindow->GetX11WindowHandle());
+        Impl::ClipboardText.Set(text.Get(), text.Length());
+        X11::XSetSelectionOwner(xDisplay, xAtomClipboard, window, CurrentTime); // CLIPBOARD
+        //X11::XSetSelectionOwner(xDisplay, xAtomPrimary, window, CurrentTime); // XA_PRIMARY
+        X11::XFlush(xDisplay);
+        X11::XGetSelectionOwner(xDisplay, xAtomClipboard);
+        //X11::XGetSelectionOwner(xDisplay, xAtomPrimary);
+    }
+    else
+    {
+        LOG(Warning, "Wayland clipboard support is not implemented yet."); // TODO: Wayland
+    }
+}
+
+void SDLClipboard::SetRawData(const Span<byte>& data)
+{
+}
+
+void SDLClipboard::SetFiles(const Array<String>& files)
+{
+}
+
+String SDLClipboard::GetText()
+{
+    if (CommandLine::Options.Headless)
+        return String::Empty;
+    String result;
+    auto mainWindow = Engine::MainWindow;
+    if (!mainWindow)
+        return result;
+    if (xDisplay)
+    {
+        X11::Window window = (X11::Window)mainWindow->GetX11WindowHandle();
+
+        Impl::ClipboardGetText(result, xAtomClipboard, xAtomUTF8String, window);
+        if (result.HasChars())
+            return result;
+        Impl::ClipboardGetText(result, xAtomClipboard, xAtomString, window);
+        if (result.HasChars())
+            return result;
+        Impl::ClipboardGetText(result, xAtomPrimary, xAtomUTF8String, window);
+        if (result.HasChars())
+            return result;
+        Impl::ClipboardGetText(result, xAtomPrimary, xAtomString, window);
+        return result;
+    }
+    else
+    {
+        LOG(Warning, "Wayland clipboard is not implemented yet."); // TODO: Wayland
+        return String::Empty;
+    }
+}
+
+Array<byte> SDLClipboard::GetRawData()
+{
+    return Array<byte>();
+}
+
+Array<String> SDLClipboard::GetFiles()
+{
+    return Array<String>();
+}
+
+bool SDLCALL SDLPlatform::X11EventHook(void *userdata, _XEvent *xevent)
+{
+    const X11::XEvent& event = *(X11::XEvent*)xevent;
+    Window* window;
+
+    // External event handling
+    xEventReceived(xevent);
+
+    if (event.type == ClientMessage)
+    {
+        if ((uint32)event.xclient.message_type == (uint32)xAtomXdndEnter)
+        {
+            // Drag&drop enter
+            X11::Window source = event.xclient.data.l[0];
+            xDnDVersion = (int32)(event.xclient.data.l[1] >> 24);
+            const char* targetTypeFiles = "text/uri-list";
+            if (event.xclient.data.l[1] & 1)
+            {
+                Property p = Impl::ReadProperty(xDisplay, source, XInternAtom(xDisplay, "XdndTypeList", 0));
+                xDnDRequested = Impl::SelectTargetFromList(xDisplay, targetTypeFiles, (X11::Atom*)p.data, p.nitems);
+                X11::XFree(p.data);
+            }
+            else
+            {
+                xDnDRequested = Impl::SelectTargetFromAtoms(xDisplay, targetTypeFiles, event.xclient.data.l[2], event.xclient.data.l[3], event.xclient.data.l[4]);
+            }
+            return false;
+        }
+        else if ((uint32)event.xclient.message_type == (uint32)xAtomXdndPosition)
+        {
+            // Drag&drop move
+            X11::XClientMessageEvent m;
+            memset(&m, 0, sizeof(m));
+            m.type = ClientMessage;
+            m.display = event.xclient.display;
+            m.window = event.xclient.data.l[0];
+            m.message_type = xAtomXdndStatus;
+            m.format = 32;
+            m.data.l[0] = event.xany.window;
+            m.data.l[1] = (xDnDRequested != 0);
+            m.data.l[2] = 0;
+            m.data.l[3] = 0;
+            m.data.l[4] = xAtomXdndActionCopy;
+            X11::XSendEvent(xDisplay, event.xclient.data.l[0], 0, NoEventMask, (X11::XEvent*)&m);
+            X11::XFlush(xDisplay);
+            xDndPos = Float2((float)(event.xclient.data.l[2]  >> 16), (float)(event.xclient.data.l[2] & 0xffff));
+            window = WindowsManager::GetByNativePtr((void*)event.xany.window);
+            if (window)
+            {
+                LinuxDropFilesData dropData;
+                xDndResult = DragDropEffect::None;
+                if (window->_dragOver)
+                {
+                    window->OnDragOver(&dropData, xDndPos, xDndResult);
+                }
+                else
+                {
+                    window->_dragOver = true;
+                    window->OnDragEnter(&dropData, xDndPos, xDndResult);
+                }
+            }
+            return false;
+        }
+        else if ((uint32)event.xclient.message_type == (uint32)xAtomXdndLeave)
+        {
+            window = WindowsManager::GetByNativePtr((void*)event.xany.window);
+            if (window && window->_dragOver)
+            {
+                window->_dragOver = false;
+                window->OnDragLeave();
+            }
+            return false;
+        }
+        else if ((uint32)event.xclient.message_type == (uint32)xAtomXdndDrop)
+        {
+            auto w = event.xany.window;
+            if (xDnDRequested != 0)
+            {
+                xDndSourceWindow = event.xclient.data.l[0];
+                if (xDnDVersion >= 1)
+                    XConvertSelection(xDisplay, xAtomXdndSelection, xDnDRequested, xAtomPrimary, w, event.xclient.data.l[2]);
+                else
+                    XConvertSelection(xDisplay, xAtomXdndSelection, xDnDRequested, xAtomPrimary, w, CurrentTime);
+            }
+            else
+            {
+                X11::XClientMessageEvent m;
+                memset(&m, 0, sizeof(m));
+                m.type = ClientMessage;
+                m.display = event.xclient.display;
+                m.window = event.xclient.data.l[0];
+                m.message_type = xAtomXdndFinished;
+                m.format = 32;
+                m.data.l[0] = w;
+                m.data.l[1] = 0;
+                m.data.l[2] = 0;
+                X11::XSendEvent(xDisplay, event.xclient.data.l[0], 0, NoEventMask, (X11::XEvent*)&m);
+            }
+            return false;
+        }
+    }
+    else if (event.type == SelectionNotify)
+    {
+        if (event.xselection.target == xDnDRequested)
+        {
+            // Drag&drop
+            window = WindowsManager::GetByNativePtr((void*)event.xany.window);
+            if (window)
+            {
+                Property p = Impl::ReadProperty(xDisplay, event.xany.window, xAtomPrimary);
+                if (xDndResult != DragDropEffect::None)
+                {
+                    LinuxDropFilesData dropData;
+                    const String filesList((const char*)p.data);
+                    filesList.Split('\n', dropData.Files);
+                    for (auto& e : dropData.Files)
+                    {
+                        e.Replace(TEXT("file://"), TEXT(""));
+                        e.Replace(TEXT("%20"), TEXT(" "));
+                        e = e.TrimTrailing();
+                    }
+                    xDndResult = DragDropEffect::None;
+                    window->OnDragDrop(&dropData, xDndPos, xDndResult);
+                }
+            }
+            X11::XClientMessageEvent m;
+            memset(&m, 0, sizeof(m));
+            m.type = ClientMessage;
+            m.display = xDisplay;
+            m.window = xDndSourceWindow;
+            m.message_type = xAtomXdndFinished;
+            m.format = 32;
+            m.data.l[0] = event.xany.window;
+            m.data.l[1] = 1;
+            m.data.l[2] = xAtomXdndActionCopy;
+            XSendEvent(xDisplay, xDndSourceWindow, 0, NoEventMask, (X11::XEvent*)&m);
+            return false;
+        }
+        return false;
+    }
+    else if (event.type == SelectionRequest)
+    {
+        if (event.xselectionrequest.selection != xAtomClipboard)
+            return false;
+        
+        const X11::XSelectionRequestEvent* xsr = &event.xselectionrequest;
+        X11::XSelectionEvent ev = { 0 };
+        ev.type = SelectionNotify;
+        ev.display = xsr->display;
+        ev.requestor = xsr->requestor;
+        ev.selection = xsr->selection;
+        ev.time = xsr->time;
+        ev.target = xsr->target;
+        ev.property = xsr->property;
+        
+        int result = 0;
+        if (ev.target == xAtomTargets)
+        {
+            Array<X11::Atom, FixedAllocation<2>> types(2);
+            types.Add(xAtomTargets);
+            types.Add(xAtomUTF8String);
+            result = X11::XChangeProperty(xDisplay, ev.requestor, ev.property, xAtomAtom, 32, PropModeReplace, (unsigned char*)types.Get(), types.Count());
+        }
+        else if (ev.target == xAtomString || ev.target == xAtomText)
+            result = X11::XChangeProperty(xDisplay, ev.requestor, ev.property, xAtomString, 8, PropModeReplace, (unsigned char*)Impl::ClipboardText.Get(), Impl::ClipboardText.Length());
+        else if (ev.target == xAtomUTF8String)
+            result = X11::XChangeProperty(xDisplay, ev.requestor, ev.property, xAtomUTF8String, 8, PropModeReplace, (unsigned char*)Impl::ClipboardText.Get(), Impl::ClipboardText.Length());
+        else
+            ev.property = 0;
+        if ((result & 2) == 0)
+            X11::XSendEvent(xDisplay, ev.requestor, 0, 0, (X11::XEvent*)&ev);
+        return false;
+    }
+    else if (event.type == SelectionClear)
+        return false;
+    else if (event.type == XFixesSelectionNotifyEvent)
+        return false;
+    return true;
+}
+
+int X11ErrorHandler(X11::Display* display, X11::XErrorEvent* event)
+{
+    if (event->error_code == 5)
+        return 0; // BadAtom (invalid Atom parameter)
+    char buffer[256];
+    XGetErrorText(display, event->error_code, buffer, sizeof(buffer));
+    LOG(Error, "X11 Error: {0}", String(buffer));
+    return 0;
+}
+
+bool SDLPlatform::InitPlatform()
+{
+    if (LinuxPlatform::Init())
+        return true;
+
+    if (!CommandLine::Options.Headless)
+    {
+        UseWayland = strcmp(SDL_GetCurrentVideoDriver(), "wayland") == 0;
+        String waylandDisplay;
+        if (/*!UseWayland &&*/ !Platform::GetEnvironmentVariable(TEXT("WAYLAND_DISPLAY"), waylandDisplay))
+            UseXWayland = waylandDisplay.Length() > 1;
+    }
+
+    return false;
+}
+
+bool SDLPlatform::InitPlatformX11(void* display)
+{
+    if (xDisplay || UseWayland)
+        return false;
+
+    // The Display instance must be the same one SDL uses internally
+    xDisplay = (X11::Display*)display;
+    SDL_SetX11EventHook((SDL_X11EventHook)&X11EventHook, nullptr);
+    X11::XSetErrorHandler(X11ErrorHandler);
+
+    //xDisplay = X11::XOpenDisplay(nullptr);
+    xAtomDeleteWindow = X11::XInternAtom(xDisplay, "WM_DELETE_WINDOW", 0);
+    xAtomXdndEnter = X11::XInternAtom(xDisplay, "XdndEnter", 0);
+    xAtomXdndPosition = X11::XInternAtom(xDisplay, "XdndPosition", 0);
+    xAtomXdndLeave = X11::XInternAtom(xDisplay, "XdndLeave", 0);
+    xAtomXdndDrop = X11::XInternAtom(xDisplay, "XdndDrop", 0);
+    xAtomXdndActionCopy = X11::XInternAtom(xDisplay, "XdndActionCopy", 0);
+    xAtomXdndStatus = X11::XInternAtom(xDisplay, "XdndStatus", 0);
+    xAtomXdndSelection = X11::XInternAtom(xDisplay, "XdndSelection", 0);
+    xAtomXdndFinished = X11::XInternAtom(xDisplay, "XdndFinished", 0);
+    xAtomXdndAware = X11::XInternAtom(xDisplay, "XdndAware", 0);
+    xAtomWmStateHidden = X11::XInternAtom(xDisplay, "_NET_WM_STATE_HIDDEN", 0);
+    xAtomWmStateMaxHorz = X11::XInternAtom(xDisplay, "_NET_WM_STATE_MAXIMIZED_HORZ", 0);
+    xAtomWmStateMaxVert = X11::XInternAtom(xDisplay, "_NET_WM_STATE_MAXIMIZED_VERT", 0);
+    xAtomWmWindowOpacity = X11::XInternAtom(xDisplay, "_NET_WM_WINDOW_OPACITY", 0);
+    xAtomWmName = X11::XInternAtom(xDisplay, "_NET_WM_NAME", 0);
+    xAtomAtom = static_cast<X11::Atom>(4); // XA_ATOM
+    xAtomClipboard = X11::XInternAtom(xDisplay, "CLIPBOARD", 0);
+    xAtomPrimary = static_cast<X11::Atom>(1); // XA_PRIMARY
+    xAtomTargets = X11::XInternAtom(xDisplay, "TARGETS", 0);
+    xAtomText = X11::XInternAtom(xDisplay, "TEXT", 0);
+    xAtomString = static_cast<X11::Atom>(31); // XA_STRING
+    xAtomUTF8String = X11::XInternAtom(xDisplay, "UTF8_STRING", 1);
+    if (xAtomUTF8String == 0)
+        xAtomUTF8String = xAtomString;
+    xAtomXselData = X11::XInternAtom(xDisplay, "XSEL_DATA", 0);
+
+    // We need to override handling of the XFixes selection tracking events from SDL
+    auto screen = X11::XDefaultScreen(xDisplay);
+    auto rootWindow = X11::XRootWindow(xDisplay, screen);
+    int eventBase = 0, errorBase = 0;
+    if (X11::XFixesQueryExtension(xDisplay, &eventBase, &errorBase))
+    {
+        XFixesSelectionNotifyEvent = eventBase + XFixesSelectionNotify;
+        X11::XFixesSelectSelectionInput(xDisplay, rootWindow, xAtomClipboard, XFixesSetSelectionOwnerNotifyMask);
+        X11::XFixesSelectSelectionInput(xDisplay, rootWindow, xAtomPrimary, XFixesSetSelectionOwnerNotifyMask);
+    }
+
+    return false;
+}
+
+void* SDLPlatform::GetXDisplay()
+{
+    return xDisplay;
+}
+
+void SDLPlatform::SetHighDpiAwarenessEnabled(bool enable)
+{
+    base::SetHighDpiAwarenessEnabled(enable);
+}
+
+bool SDLPlatform::UsesWayland()
+{
+    return UseWayland;
+}
+
+bool SDLPlatform::UsesXWayland()
+{
+    return UseXWayland;
+}
+
+bool SDLPlatform::UsesX11()
+{
+    return !UseWayland;
+}
+
+#endif

Source/Engine/Platform/SDL/SDLPlatform.Mac.cpp

@@ -0,0 +1,12 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+#if PLATFORM_SDL && PLATFORM_MAC
+
+static_assert(false, "TODO");
+
+void SDLPlatform::SetHighDpiAwarenessEnabled(bool enable)
+{
+    // TODO: This is now called before Platform::Init, ensure the scaling is changed accordingly during Platform::Init (see ApplePlatform::SetHighDpiAwarenessEnabled)
+}
+
+#endif

Source/Engine/Platform/SDL/SDLPlatform.Windows.cpp

@@ -0,0 +1,64 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+
+#if PLATFORM_SDL && PLATFORM_WINDOWS
+
+#include "SDLPlatform.h"
+#include "Engine/Core/Collections/Array.h"
+#include "Engine/Platform/WindowsManager.h"
+#include "Engine/Platform/Win32/IncludeWindowsHeaders.h"
+
+#include <SDL3/SDL_hints.h>
+#include <SDL3/SDL_init.h>
+#include <SDL3/SDL_system.h>
+
+// The events for releasing the mouse during window dragging are missing, handle the mouse release event here
+bool SDLCALL SDLPlatform::EventMessageHook(void* userdata, MSG* msg)
+{
+#define GET_WINDOW_WITH_HWND(window, hwnd) \
+    do { \
+        (window) = nullptr; \
+        WindowsManager::WindowsLocker.Lock(); \
+        for (int32 i = 0; i < WindowsManager::Windows.Count(); i++) \
+        { \
+            if (WindowsManager::Windows[i]->GetNativePtr() == (hwnd)) \
+            { \
+                (window) = WindowsManager::Windows[i]; \
+                break; \
+            } \
+        } \
+        WindowsManager::WindowsLocker.Unlock(); \
+        ASSERT((window) != nullptr); \
+    } while (false)
+
+    if (msg->message == WM_NCLBUTTONDOWN)
+    {
+        Window* window;
+        GET_WINDOW_WITH_HWND(window, msg->hwnd);
+        
+        auto hit = static_cast<WindowHitCodes>(msg->wParam);
+        if (SDLPlatform::CheckWindowDragging(window, hit))
+            return false;
+    }
+    return true;
+#undef GET_WINDOW_WITH_HWND
+}
+
+bool SDLPlatform::InitPlatform()
+{
+    // Workaround required for handling window dragging events properly for DockHintWindow
+    SDL_SetWindowsMessageHook(&EventMessageHook, nullptr);
+
+    if (WindowsPlatform::Init())
+        return true;
+
+    return false;
+}
+
+void SDLPlatform::SetHighDpiAwarenessEnabled(bool enable)
+{
+    // Other supported values: "permonitor", "permonitorv2"
+    SDL_SetHint("SDL_WINDOWS_DPI_AWARENESS", enable ? "system" : "unaware");
+}
+
+#endif

Source/Engine/Platform/SDL/SDLPlatform.cpp

@@ -0,0 +1,493 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+#if PLATFORM_SDL
+
+#include "SDLPlatform.h"
+#include "SDLWindow.h"
+#include "Engine/Core/Log.h"
+#include "Engine/Input/Input.h"
+#include "Engine/Input/Mouse.h"
+#include "Engine/Platform/BatteryInfo.h"
+#include "Engine/Platform/WindowsManager.h"
+#include "Engine/Platform/SDL/SDLInput.h"
+
+#include <SDL3/SDL_hints.h>
+#include <SDL3/SDL_init.h>
+#include <SDL3/SDL_misc.h>
+#include <SDL3/SDL_power.h>
+#include <SDL3/SDL_revision.h>
+#include <SDL3/SDL_system.h>
+#include <SDL3/SDL_version.h>
+#include <SDL3/SDL_locale.h>
+
+#if PLATFORM_LINUX
+#include "Engine/Engine/CommandLine.h"
+#include "Engine/Platform/MessageBox.h"
+#include <SDL3/SDL_messagebox.h>
+#endif
+
+#define DefaultDPI 96
+
+uint32 SDLPlatform::DraggedWindowId = 0;
+
+namespace
+{
+    int32 SystemDpi = 96;
+    String UserLocale("en");
+}
+
+bool SDLPlatform::Init()
+{
+#if PLATFORM_LINUX
+    if (CommandLine::Options.X11)
+        SDL_SetHintWithPriority(SDL_HINT_VIDEO_DRIVER, "x11", SDL_HINT_OVERRIDE);
+    else if (CommandLine::Options.Wayland)
+        SDL_SetHintWithPriority(SDL_HINT_VIDEO_DRIVER, "wayland", SDL_HINT_OVERRIDE);
+    //SDL_SetHintWithPriority(SDL_HINT_VIDEO_DRIVER, "wayland", SDL_HINT_OVERRIDE);
+    // If the hint is not present, SDL will prefer more stable X11 driver over Wayland
+#endif
+
+#if PLATFORM_LINUX
+    // TODO: This should be read from the platform configuration (needed for desktop icon handling)
+#if USE_EDITOR
+    SDL_SetHint(SDL_HINT_APP_ID, StringAnsi("com.FlaxEngine.FlaxEditor").Get());
+#else
+    SDL_SetHint(SDL_HINT_APP_ID, StringAnsi("com.FlaxEngine.FlaxGame").Get());
+#endif
+#else
+    SDL_SetHint(SDL_HINT_APP_ID, StringAnsi(ApplicationClassName).Get());
+#endif
+
+    SDL_SetHint(SDL_HINT_WINDOW_ACTIVATE_WHEN_SHOWN, "0");
+    SDL_SetHint(SDL_HINT_WINDOW_ACTIVATE_WHEN_RAISED, "0");
+    SDL_SetHint(SDL_HINT_MOUSE_FOCUS_CLICKTHROUGH, "1"); // Fixes context menu focus issues when clicking unfocused menus
+    SDL_SetHint(SDL_HINT_WINDOWS_ERASE_BACKGROUND_MODE, "0");
+    SDL_SetHint(SDL_HINT_TIMER_RESOLUTION, "0"); // Already handled during platform initialization
+    SDL_SetHint("SDL_BORDERLESS_RESIZABLE_STYLE", "1"); // Allow borderless windows to be resizable on Windows
+    //SDL_SetHint("SDL_BORDERLESS_WINDOWED_STYLE", "1"); 
+    
+    SDL_SetHint(SDL_HINT_MOUSE_RELATIVE_WARP_MOTION, "0");
+    SDL_SetHint(SDL_HINT_MOUSE_RELATIVE_CURSOR_VISIBLE, "1"); // Needed for tracking mode
+    SDL_SetHint(SDL_HINT_MOUSE_RELATIVE_MODE_CENTER, "1"); // Is this needed?
+
+    //SDL_SetHint(SDL_HINT_MOUSE_RELATIVE_MODE_WARP, "1"); // Disables raw mouse input
+    SDL_SetHint(SDL_HINT_WINDOWS_RAW_KEYBOARD, "1");
+
+    SDL_SetHint(SDL_HINT_VIDEO_WAYLAND_SCALE_TO_DISPLAY, "1");
+
+    // Disable SDL clipboard support
+    SDL_SetEventEnabled(SDL_EVENT_CLIPBOARD_UPDATE, false);
+
+    // Disable SDL drag and drop support
+    SDL_SetEventEnabled(SDL_EVENT_DROP_FILE, false);
+    SDL_SetEventEnabled(SDL_EVENT_DROP_TEXT, false);
+    SDL_SetEventEnabled(SDL_EVENT_DROP_BEGIN, false);
+    SDL_SetEventEnabled(SDL_EVENT_DROP_COMPLETE, false);
+    SDL_SetEventEnabled(SDL_EVENT_DROP_POSITION, false);
+
+    if (!SDL_InitSubSystem(SDL_INIT_VIDEO | SDL_INIT_GAMEPAD))
+        Platform::Fatal(String::Format(TEXT("Failed to initialize SDL: {0}."), String(SDL_GetError())));
+
+    int localesCount = 0;
+    auto locales = SDL_GetPreferredLocales(&localesCount);
+    for (int i = 0; i < localesCount; i++)
+    {
+        auto language = StringAnsiView(locales[i]->language);
+        auto country = StringAnsiView(locales[i]->country);
+        if (language.StartsWith("en"))
+        {
+            if (country != nullptr)
+                UserLocale = String::Format(TEXT("{0}-{1}"), String(language), String(locales[i]->country));
+            else
+                UserLocale = String(language);
+            break;
+        }
+    }
+    SDL_free(locales);
+    
+    if (InitPlatform())
+        return true;
+
+    SDLInput::Init();
+
+    SystemDpi = (int)(SDL_GetDisplayContentScale(SDL_GetPrimaryDisplay()) * DefaultDPI);
+
+    //SDL_StartTextInput(); // TODO: Call this only when text input is expected (shows virtual keyboard in some cases)
+
+    return base::Init();
+}
+
+void SDLPlatform::LogInfo()
+{
+    base::LogInfo();
+
+    const int32 runtimeVersion = SDL_GetVersion();
+    LOG(Info, "Using SDL version {}.{}.{} ({}), runtime: {}.{}.{} ({})",
+        SDL_VERSIONNUM_MAJOR(SDL_VERSION), SDL_VERSIONNUM_MINOR(SDL_VERSION), SDL_VERSIONNUM_MICRO(SDL_VERSION), String(SDL_REVISION),
+        SDL_VERSIONNUM_MAJOR(runtimeVersion), SDL_VERSIONNUM_MINOR(runtimeVersion), SDL_VERSIONNUM_MICRO(runtimeVersion), String(SDL_GetRevision()));
+
+    LOG(Info, "SDL video driver: {}", String(SDL_GetCurrentVideoDriver()));
+}
+
+bool SDLPlatform::CheckWindowDragging(Window* window, WindowHitCodes hit)
+{
+    bool handled = false;
+    window->OnLeftButtonHit(hit, handled);
+    if (handled)
+        DraggedWindowId = window->_windowId;
+    return handled;
+}
+
+void SDLPlatform::Tick()
+{
+    SDLInput::Update();
+
+    if (DraggedWindowId != 0)
+    {
+        Float2 mousePos;
+        auto buttons = SDL_GetGlobalMouseState(&mousePos.X, &mousePos.Y);
+        if (!(buttons & SDL_BUTTON_MASK(SDL_BUTTON_LEFT)))
+        {
+            Window* window = nullptr;
+            WindowsManager::WindowsLocker.Lock();
+            for (int32 i = 0; i < WindowsManager::Windows.Count(); i++)
+            {
+                if (WindowsManager::Windows[i]->_windowId == DraggedWindowId)
+                {
+                    window = WindowsManager::Windows[i];
+                    break;
+                }
+            }
+            WindowsManager::WindowsLocker.Unlock();
+
+            if (window != nullptr)
+            {
+                int top, left, bottom, right;
+                SDL_GetWindowBordersSize(window->_window, &top, &left, &bottom, &right);
+                mousePos += Float2(static_cast<float>(left), static_cast<float>(-top));
+                Input::Mouse->OnMouseUp(mousePos, MouseButton::Left, window);
+            }
+            DraggedWindowId = 0;
+        }
+        else
+        {
+#if PLATFORM_LINUX
+            String dockHintWindow("DockHint.Window");
+            Window* window = nullptr;
+            WindowsManager::WindowsLocker.Lock();
+            for (int32 i = 0; i < WindowsManager::Windows.Count(); i++)
+            {
+                if (WindowsManager::Windows[i]->_title.Compare(dockHintWindow) == 0)
+                //if (WindowsManager::Windows[i]->_windowId == DraggedWindowId)
+                {
+                    window = WindowsManager::Windows[i];
+                    break;
+                }
+            }
+            WindowsManager::WindowsLocker.Unlock();
+
+            if (window != nullptr)
+            {
+                int top, left, bottom, right;
+                SDL_GetWindowBordersSize(window->_window, &top, &left, &bottom, &right);
+                mousePos += Float2(static_cast<float>(left), static_cast<float>(-top));
+                Input::Mouse->OnMouseMove(mousePos, window);
+            }
+#endif
+        }
+    }
+
+    SDL_PumpEvents();
+    SDL_Event events[32];
+    int count = SDL_PeepEvents(events, SDL_arraysize(events), SDL_GETEVENT, SDL_EVENT_FIRST, SDL_EVENT_LAST);
+    for (int i = 0; i < count; ++i)
+    {
+        SDLWindow* window = SDLWindow::GetWindowFromEvent(events[i]);
+        if (window)
+            window->HandleEvent(events[i]);
+        else if (events[i].type >= SDL_EVENT_JOYSTICK_AXIS_MOTION && events[i].type <= SDL_EVENT_GAMEPAD_STEAM_HANDLE_UPDATED)
+            SDLInput::HandleEvent(nullptr, events[i]);
+        else
+            SDLPlatform::HandleEvent(events[i]);
+    }
+}
+
+bool SDLPlatform::HandleEvent(SDL_Event& event)
+{
+    return true;
+}
+
+BatteryInfo SDLPlatform::GetBatteryInfo()
+{
+    BatteryInfo info;
+    int percentage;
+    SDL_PowerState powerState = SDL_GetPowerInfo(nullptr, &percentage);
+
+    if (percentage < 0)
+        info.BatteryLifePercent = 1.0f;
+    else
+        info.BatteryLifePercent = (float)percentage / 100.0f;
+
+    switch (powerState)
+    {
+    case SDL_POWERSTATE_CHARGING:
+        info.State = BatteryInfo::States::BatteryCharging;
+        break;
+    case SDL_POWERSTATE_ON_BATTERY:
+        info.State = BatteryInfo::States::BatteryDischarging;
+        break;
+    case SDL_POWERSTATE_CHARGED:
+        info.State = BatteryInfo::States::Connected;
+        break;
+    default:
+        info.State = BatteryInfo::States::Unknown;
+    }
+    return info;
+}
+
+int32 SDLPlatform::GetDpi()
+{
+    return SystemDpi;
+}
+
+String SDLPlatform::GetUserLocaleName()
+{
+    return UserLocale;
+}
+
+void SDLPlatform::OpenUrl(const StringView& url)
+{
+    StringAnsi urlStr(url);
+    SDL_OpenURL(urlStr.GetText());
+}
+
+Float2 SDLPlatform::GetMousePosition()
+{
+    Float2 pos;
+    SDL_GetGlobalMouseState(&pos.X, &pos.Y);
+    return pos;
+}
+
+void SDLPlatform::SetMousePosition(const Float2& pos)
+{
+    SDL_WarpMouseGlobal(pos.X, pos.Y);
+}
+
+Float2 SDLPlatform::GetDesktopSize()
+{
+    SDL_Rect rect;
+    SDL_GetDisplayBounds(SDL_GetPrimaryDisplay(), &rect);
+    return Float2(static_cast<float>(rect.w), static_cast<float>(rect.h));
+}
+
+Rectangle SDLPlatform::GetMonitorBounds(const Float2& screenPos)
+{
+    SDL_Point point{ (int32)screenPos.X, (int32)screenPos.Y };
+    SDL_DisplayID display = SDL_GetDisplayForPoint(&point);
+    SDL_Rect rect;
+    SDL_GetDisplayBounds(display, &rect);
+    return Rectangle(static_cast<float>(rect.x), static_cast<float>(rect.y), static_cast<float>(rect.w), static_cast<float>(rect.h));
+}
+
+Rectangle SDLPlatform::GetVirtualDesktopBounds()
+{
+    int count;
+    const SDL_DisplayID* displays = SDL_GetDisplays(&count);
+    if (displays == nullptr)
+        return Rectangle::Empty;
+
+    Rectangle bounds = Rectangle::Empty;
+    for (int i = 0; i < count; i++)
+    {
+        SDL_DisplayID display = displays[i];
+        SDL_Rect rect;
+        SDL_GetDisplayBounds(display, &rect);
+        bounds = Rectangle::Union(bounds, Rectangle(static_cast<float>(rect.x), static_cast<float>(rect.y), static_cast<float>(rect.w), static_cast<float>(rect.h)));
+    }
+    SDL_free((void*)displays);
+    return bounds;
+}
+
+Window* SDLPlatform::CreateWindow(const CreateWindowSettings& settings)
+{
+    return New<SDLWindow>(settings);
+}
+
+#if !PLATFORM_LINUX
+
+bool SDLPlatform::UsesWayland()
+{
+    return false;
+}
+
+bool SDLPlatform::UsesXWayland()
+{
+    return false;
+}
+
+bool SDLPlatform::UsesX11()
+{
+    return false;
+}
+
+#endif
+
+#if PLATFORM_LINUX
+DialogResult MessageBox::Show(Window* parent, const StringView& text, const StringView& caption, MessageBoxButtons buttons, MessageBoxIcon icon)
+{
+    StringAnsi textAnsi(text);
+    StringAnsi captionAnsi(caption);
+
+    SDL_MessageBoxData data;
+    SDL_MessageBoxButtonData dataButtons[3];
+    data.window = parent ? static_cast<SDLWindow*>(parent)->_window : nullptr;
+    data.title = captionAnsi.GetText();
+    data.message = textAnsi.GetText();
+    data.colorScheme = nullptr;
+
+    switch (icon)
+    {
+    case MessageBoxIcon::Error:
+    case MessageBoxIcon::Hand:
+    case MessageBoxIcon::Stop:
+        data.flags |= SDL_MESSAGEBOX_ERROR;
+        break;
+    case MessageBoxIcon::Asterisk:
+    case MessageBoxIcon::Information:
+    case MessageBoxIcon::Question:
+        data.flags |= SDL_MESSAGEBOX_INFORMATION;
+        break;
+    case MessageBoxIcon::Exclamation:
+    case MessageBoxIcon::Warning:
+        data.flags |= SDL_MESSAGEBOX_WARNING;
+        break;
+    default:
+        break;
+    }
+
+    switch (buttons)
+    {
+    case MessageBoxButtons::AbortRetryIgnore:
+        dataButtons[0] =
+        {
+            SDL_MESSAGEBOX_BUTTON_ESCAPEKEY_DEFAULT,
+            (int)DialogResult::Abort,
+            "Abort"
+        };
+        dataButtons[1] =
+        {
+            SDL_MESSAGEBOX_BUTTON_RETURNKEY_DEFAULT,
+            (int)DialogResult::Retry,
+            "Retry"
+        };
+        dataButtons[2] =
+        {
+            0,
+            (int)DialogResult::Ignore,
+            "Ignore"
+        };
+        data.numbuttons = 3;
+        break;
+    case MessageBoxButtons::OK:
+        dataButtons[0] =
+        {
+            SDL_MESSAGEBOX_BUTTON_RETURNKEY_DEFAULT | SDL_MESSAGEBOX_BUTTON_ESCAPEKEY_DEFAULT,
+            (int)DialogResult::OK,
+            "OK"
+        };
+        data.numbuttons = 1;
+        break;
+    case MessageBoxButtons::OKCancel:
+        dataButtons[0] =
+        {
+            SDL_MESSAGEBOX_BUTTON_RETURNKEY_DEFAULT,
+            (int)DialogResult::OK,
+            "OK"
+        };
+        dataButtons[1] =
+        {
+            SDL_MESSAGEBOX_BUTTON_ESCAPEKEY_DEFAULT,
+            (int)DialogResult::Cancel,
+            "Cancel"
+        };
+        data.numbuttons = 2;
+        break;
+    case MessageBoxButtons::RetryCancel:
+        dataButtons[0] =
+        {
+            SDL_MESSAGEBOX_BUTTON_RETURNKEY_DEFAULT,
+            (int)DialogResult::Retry,
+            "Retry"
+        };
+        dataButtons[1] =
+        {
+            SDL_MESSAGEBOX_BUTTON_ESCAPEKEY_DEFAULT,
+            (int)DialogResult::Cancel,
+            "Cancel"
+        };
+        data.numbuttons = 2;
+        break;
+    case MessageBoxButtons::YesNo:
+        dataButtons[0] =
+        {
+            SDL_MESSAGEBOX_BUTTON_RETURNKEY_DEFAULT,
+            (int)DialogResult::Yes,
+            "Yes"
+        };
+        dataButtons[1] =
+        {
+            SDL_MESSAGEBOX_BUTTON_ESCAPEKEY_DEFAULT,
+            (int)DialogResult::No,
+            "No"
+        };
+        data.numbuttons = 2;
+        break;
+    case MessageBoxButtons::YesNoCancel:
+    {
+        dataButtons[0] =
+        {
+            SDL_MESSAGEBOX_BUTTON_RETURNKEY_DEFAULT,
+            (int)DialogResult::Yes,
+            "Yes"
+        };
+        dataButtons[1] =
+        {
+            0,
+            (int)DialogResult::No,
+            "No"
+        };
+        dataButtons[2] =
+        {
+            SDL_MESSAGEBOX_BUTTON_ESCAPEKEY_DEFAULT,
+            (int)DialogResult::Cancel,
+            "Cancel"
+        };
+        data.numbuttons = 3;
+        break;
+    }
+    default:
+        break;
+    }
+    data.buttons = dataButtons;
+
+    int result = -1;
+    if (!SDL_ShowMessageBox(&data, &result))
+    {
+#if PLATFORM_LINUX
+        // Fallback to native messagebox implementation in case some system fonts are missing
+        if (SDLPlatform::UsesX11())
+        {
+            LOG(Warning, "Failed to show SDL message box: {0}", String(SDL_GetError()));
+            return ShowFallback(parent, text, caption, buttons, icon);
+        }
+#endif
+        LOG(Error, "Failed to show SDL message box: {0}", String(SDL_GetError()));
+        return DialogResult::Abort;
+    }
+    if (result < 0)
+        return DialogResult::None;
+    return (DialogResult)result;
+}
+#endif
+
+#endif

Source/Engine/Platform/SDL/SDLPlatform.h

@@ -0,0 +1,83 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#if PLATFORM_SDL
+
+#include "Engine/Platform/Base/Enums.h"
+#if PLATFORM_WINDOWS
+#include "Engine/Platform/Windows/WindowsPlatform.h"
+#elif PLATFORM_LINUX
+#include "Engine/Platform/Linux/LinuxPlatform.h"
+#else
+#endif
+
+class SDLWindow;
+union SDL_Event;
+#if PLATFORM_WINDOWS
+typedef struct tagMSG MSG;
+#elif PLATFORM_LINUX
+union _XEvent;
+#endif
+
+/// <summary>
+/// The Windows platform implementation and application management utilities.
+/// </summary>
+class FLAXENGINE_API SDLPlatform
+#if PLATFORM_WINDOWS
+    : public WindowsPlatform
+{
+    using base = WindowsPlatform;
+#elif PLATFORM_LINUX
+    : public LinuxPlatform
+{
+    using base = LinuxPlatform;
+#else
+{
+#endif
+    friend SDLWindow;
+
+private:
+    static uint32 DraggedWindowId;
+
+private:
+    static bool InitPlatform();
+#if PLATFORM_LINUX
+    static bool InitPlatformX11(void* display);
+#endif
+    static bool HandleEvent(SDL_Event& event);
+#if PLATFORM_WINDOWS
+    static bool __cdecl EventMessageHook(void* userdata, MSG* msg);
+#elif PLATFORM_LINUX
+    static bool __cdecl X11EventHook(void *userdata, _XEvent *xevent);
+#endif
+
+public:
+    static bool CheckWindowDragging(Window* window, WindowHitCodes hit);
+#if PLATFORM_LINUX
+    static void* GetXDisplay();
+#endif
+    static bool UsesWayland();
+    static bool UsesXWayland();
+    static bool UsesX11();
+
+public:
+
+    // [PlatformBase]
+    static bool Init();
+    static void LogInfo();
+    static void Tick();
+    static void SetHighDpiAwarenessEnabled(bool enable);
+    static BatteryInfo GetBatteryInfo();
+    static int32 GetDpi();
+    static String GetUserLocaleName();
+    static void OpenUrl(const StringView& url);
+    static Float2 GetMousePosition();
+    static void SetMousePosition(const Float2& pos);
+    static Float2 GetDesktopSize();
+    static Rectangle GetMonitorBounds(const Float2& screenPos);
+    static Rectangle GetVirtualDesktopBounds();
+    static Window* CreateWindow(const CreateWindowSettings& settings);
+};
+
+#endif

Source/Engine/Platform/SDL/SDLWindow.h

@@ -0,0 +1,126 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#if PLATFORM_SDL
+
+#include "Engine/Platform/Base/WindowBase.h"
+
+struct SDL_Window;
+union SDL_Event;
+#if PLATFORM_LINUX
+class MessageBox;
+#endif
+
+/// <summary>
+/// Implementation of the window class for SDL platform
+/// </summary>
+class FLAXENGINE_API SDLWindow : public WindowBase
+#if USE_EDITOR && PLATFORM_WINDOWS
+    , public Windows::IDropTarget
+#endif
+{
+    friend SDLPlatform;
+    friend class SDLMouse;
+#if PLATFORM_LINUX
+    friend LinuxPlatform;
+    friend MessageBox;
+#endif
+    
+private:
+    void* _handle; // Opaque, platform specific window handle
+#if USE_EDITOR && PLATFORM_WINDOWS
+    Windows::ULONG _refCount;
+#endif
+#if PLATFORM_LINUX
+    bool _dragOver;
+    bool _forcedFocus;
+#endif
+    SDL_Window* _window;
+    uint32 _windowId;
+    Rectangle _clipCursorRect;
+    Rectangle _cachedClientRectangle;
+
+public:
+    /// <summary>
+    /// Initializes a new instance of the <see cref="SDLWindow"/> class.
+    /// </summary>
+    /// <param name="settings">The initial window settings.</param>
+    SDLWindow(const CreateWindowSettings& settings);
+
+    /// <summary>
+    /// Finalizes an instance of the <see cref="SDLWindow"/> class.
+    /// </summary>
+    ~SDLWindow();
+
+private:
+
+    static SDLWindow* GetWindowFromEvent(const SDL_Event& event);
+    static SDLWindow* GetWindowWithSDLWindow(SDL_Window* window);
+    void HandleEvent(SDL_Event& event);
+    void CheckForWindowResize();
+    void UpdateCursor();
+
+#if PLATFORM_LINUX
+    DragDropEffect DoDragDropWayland(const StringView& data);
+    DragDropEffect DoDragDropX11(const StringView& data);
+#endif
+
+public:
+
+    SDL_Window* GetSDLWindow() const;
+#if PLATFORM_LINUX
+    void* GetWaylandSurfacePtr() const;
+    void* GetWaylandDisplay() const;
+    uintptr GetX11WindowHandle() const;
+    void* GetX11Display() const;
+#endif
+
+    // [WindowBase]
+    void* GetNativePtr() const override;
+    void Show() override;
+    void Hide() override;
+    void Minimize() override;
+    void Maximize() override;
+    void SetBorderless(bool isBorderless, bool maximized = false) override;
+    void Restore() override;
+    bool IsClosed() const override;
+    bool IsForegroundWindow() const override;
+    void BringToFront(bool force = false) override;
+    void SetClientBounds(const Rectangle& clientArea) override;
+    void SetPosition(const Float2& position) override;
+    void SetClientPosition(const Float2& position) override;
+    void SetIsFullscreen(bool isFullscreen) override;
+    Float2 GetPosition() const override;
+    Float2 GetSize() const override;
+    Float2 GetClientSize() const override;
+    Float2 ScreenToClient(const Float2& screenPos) const override;
+    Float2 ClientToScreen(const Float2& clientPos) const override;
+    void FlashWindow() override;
+    float GetOpacity() const override;
+    void SetOpacity(float opacity) override;
+    void Focus() override;
+    String GetTitle() const override;
+    void SetTitle(const StringView& title) override;
+    DragDropEffect DoDragDrop(const StringView& data) override;
+    void StartTrackingMouse(bool useMouseScreenOffset) override;
+    void EndTrackingMouse() override;
+    void StartClippingCursor(const Rectangle& bounds) override;
+    void EndClippingCursor() override;
+    void SetCursor(CursorType type) override;
+
+#if USE_EDITOR && PLATFORM_WINDOWS
+    // [IUnknown]
+    Windows::HRESULT __stdcall QueryInterface(const Windows::IID& id, void** ppvObject) override;
+    Windows::ULONG __stdcall AddRef() override;
+    Windows::ULONG __stdcall Release() override;
+
+    // [Windows::IDropTarget]
+    Windows::HRESULT __stdcall DragEnter(Windows::IDataObject* pDataObj, Windows::DWORD grfKeyState, Windows::POINTL pt, Windows::DWORD* pdwEffect) override;
+    Windows::HRESULT __stdcall DragOver(Windows::DWORD grfKeyState, Windows::POINTL pt, Windows::DWORD* pdwEffect) override;
+    Windows::HRESULT __stdcall DragLeave() override;
+    Windows::HRESULT __stdcall Drop(Windows::IDataObject* pDataObj, Windows::DWORD grfKeyState, Windows::POINTL pt, Windows::DWORD* pdwEffect) override;
+#endif
+};
+
+#endif

Source/Engine/Platform/ScreenUtilities.h

@@ -0,0 +1,15 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#if PLATFORM_WINDOWS
+#include "Windows/WindowsScreenUtilities.h"
+#elif PLATFORM_LINUX
+#include "Linux/LinuxScreenUtilities.h"
+#elif PLATFORM_MAC
+#include "Mac/MacScreenUtilities.h"
+#else
+#include "Base/ScreenUtilitiesBase.h"
+#endif
+
+#include "Types.h"

Source/Engine/Platform/Types.h

@@ -4,8 +4,6 @@
 
 #if PLATFORM_WINDOWS
 
-class WindowsClipboard;
-typedef WindowsClipboard Clipboard;
 class Win32CriticalSection;
 typedef Win32CriticalSection CriticalSection;
 class Win32ConditionVariable;
@@ -16,21 +14,25 @@ class WindowsFileSystemWatcher;
 typedef WindowsFileSystemWatcher FileSystemWatcher;
 class Win32File;
 typedef Win32File File;
-class WindowsPlatform;
-typedef WindowsPlatform Platform;
 class Win32Thread;
 typedef Win32Thread Thread;
+class WindowsClipboard;
+typedef WindowsClipboard Clipboard;
+#if !PLATFORM_SDL
+class WindowsPlatform;
+typedef WindowsPlatform Platform;
 class WindowsWindow;
 typedef WindowsWindow Window;
+#endif
 class Win32Network;
 typedef Win32Network Network;
 class UserBase;
 typedef UserBase User;
+class WindowsScreenUtilities;
+typedef WindowsScreenUtilities ScreenUtilities;
 
 #elif PLATFORM_UWP
 
-class ClipboardBase;
-typedef ClipboardBase Clipboard;
 class Win32CriticalSection;
 typedef Win32CriticalSection CriticalSection;
 class Win32ConditionVariable;
@@ -41,21 +43,23 @@ class FileSystemWatcherBase;
 typedef FileSystemWatcherBase FileSystemWatcher;
 class Win32File;
 typedef Win32File File;
-class UWPPlatform;
-typedef UWPPlatform Platform;
 class Win32Thread;
 typedef Win32Thread Thread;
+class ClipboardBase;
+typedef ClipboardBase Clipboard;
+class UWPPlatform;
+typedef UWPPlatform Platform;
 class UWPWindow;
 typedef UWPWindow Window;
 class Win32Network;
 typedef Win32Network Network;
 class UserBase;
 typedef UserBase User;
+class ScreenUtilitiesBase;
+typedef ScreenUtilitiesBase ScreenUtilities;
 
 #elif PLATFORM_LINUX
 
-class LinuxClipboard;
-typedef LinuxClipboard Clipboard;
 class UnixCriticalSection;
 typedef UnixCriticalSection CriticalSection;
 class UnixConditionVariable;
@@ -66,21 +70,25 @@ class LinuxFileSystemWatcher;
 typedef LinuxFileSystemWatcher FileSystemWatcher;
 class UnixFile;
 typedef UnixFile File;
-class LinuxPlatform;
-typedef LinuxPlatform Platform;
 class LinuxThread;
 typedef LinuxThread Thread;
+#if !PLATFORM_SDL
+class LinuxClipboard;
+typedef LinuxClipboard Clipboard;
+class LinuxPlatform;
+typedef LinuxPlatform Platform;
 class LinuxWindow;
 typedef LinuxWindow Window;
+#endif
 class UnixNetwork;
 typedef UnixNetwork Network;
 class UserBase;
 typedef UserBase User;
+class LinuxScreenUtilities;
+typedef LinuxScreenUtilities ScreenUtilities;
 
 #elif PLATFORM_PS4
 
-class ClipboardBase;
-typedef ClipboardBase Clipboard;
 class UnixCriticalSection;
 typedef UnixCriticalSection CriticalSection;
 class UnixConditionVariable;
@@ -91,21 +99,23 @@ class FileSystemWatcherBase;
 typedef FileSystemWatcherBase FileSystemWatcher;
 class UnixFile;
 typedef UnixFile File;
-class PS4Platform;
-typedef PS4Platform Platform;
 class PS4Thread;
 typedef PS4Thread Thread;
+class ClipboardBase;
+typedef ClipboardBase Clipboard;
+class PS4Platform;
+typedef PS4Platform Platform;
 class PS4Window;
 typedef PS4Window Window;
 class PS4Network;
 typedef PS4Network Network;
 class PS4User;
 typedef PS4User User;
+class ScreenUtilitiesBase;
+typedef ScreenUtilitiesBase ScreenUtilities;
 
 #elif PLATFORM_PS5
 
-class ClipboardBase;
-typedef ClipboardBase Clipboard;
 class UnixCriticalSection;
 typedef UnixCriticalSection CriticalSection;
 class UnixConditionVariable;
@@ -116,21 +126,23 @@ class FileSystemWatcherBase;
 typedef FileSystemWatcherBase FileSystemWatcher;
 class UnixFile;
 typedef UnixFile File;
-class PS5Platform;
-typedef PS5Platform Platform;
+class ClipboardBase;
+typedef ClipboardBase Clipboard;
 class PS5Thread;
 typedef PS5Thread Thread;
+class PS5Platform;
+typedef PS5Platform Platform;
 class PS5Window;
 typedef PS5Window Window;
 class PS5Network;
 typedef PS5Network Network;
 class PS5User;
 typedef PS5User User;
+class ScreenUtilitiesBase;
+typedef ScreenUtilitiesBase ScreenUtilities;
 
 #elif PLATFORM_XBOX_ONE
 
-class ClipboardBase;
-typedef ClipboardBase Clipboard;
 class Win32CriticalSection;
 typedef Win32CriticalSection CriticalSection;
 class Win32ConditionVariable;
@@ -141,21 +153,23 @@ class FileSystemWatcherBase;
 typedef FileSystemWatcherBase FileSystemWatcher;
 class Win32File;
 typedef Win32File File;
-class XboxOnePlatform;
-typedef XboxOnePlatform Platform;
 class Win32Thread;
 typedef Win32Thread Thread;
+class ClipboardBase;
+typedef ClipboardBase Clipboard;
+class XboxOnePlatform;
+typedef XboxOnePlatform Platform;
 class GDKWindow;
 typedef GDKWindow Window;
 class Win32Network;
 typedef Win32Network Network;
 class GDKUser;
 typedef GDKUser User;
+class ScreenUtilitiesBase;
+typedef ScreenUtilitiesBase ScreenUtilities;
 
 #elif PLATFORM_XBOX_SCARLETT
 
-class ClipboardBase;
-typedef ClipboardBase Clipboard;
 class Win32CriticalSection;
 typedef Win32CriticalSection CriticalSection;
 class Win32ConditionVariable;
@@ -166,21 +180,23 @@ class FileSystemWatcherBase;
 typedef FileSystemWatcherBase FileSystemWatcher;
 class Win32File;
 typedef Win32File File;
-class XboxScarlettPlatform;
-typedef XboxScarlettPlatform Platform;
 class Win32Thread;
 typedef Win32Thread Thread;
+class ClipboardBase;
+typedef ClipboardBase Clipboard;
+class XboxScarlettPlatform;
+typedef XboxScarlettPlatform Platform;
 class GDKWindow;
 typedef GDKWindow Window;
 class Win32Network;
 typedef Win32Network Network;
 class GDKUser;
 typedef GDKUser User;
+class ScreenUtilitiesBase;
+typedef ScreenUtilitiesBase ScreenUtilities;
 
 #elif PLATFORM_ANDROID
 
-class ClipboardBase;
-typedef ClipboardBase Clipboard;
 class UnixCriticalSection;
 typedef UnixCriticalSection CriticalSection;
 class UnixConditionVariable;
@@ -191,21 +207,23 @@ class FileSystemWatcherBase;
 typedef FileSystemWatcherBase FileSystemWatcher;
 class AndroidFile;
 typedef AndroidFile File;
-class AndroidPlatform;
-typedef AndroidPlatform Platform;
 class AndroidThread;
 typedef AndroidThread Thread;
+class ClipboardBase;
+typedef ClipboardBase Clipboard;
+class AndroidPlatform;
+typedef AndroidPlatform Platform;
 class AndroidWindow;
 typedef AndroidWindow Window;
 class UnixNetwork;
 typedef UnixNetwork Network;
 class UserBase;
 typedef UserBase User;
+class ScreenUtilitiesBase;
+typedef ScreenUtilitiesBase ScreenUtilities;
 
 #elif PLATFORM_SWITCH
 
-class ClipboardBase;
-typedef ClipboardBase Clipboard;
 class SwitchCriticalSection;
 typedef SwitchCriticalSection CriticalSection;
 class SwitchConditionVariable;
@@ -216,21 +234,23 @@ class FileSystemWatcherBase;
 typedef FileSystemWatcherBase FileSystemWatcher;
 class SwitchFile;
 typedef SwitchFile File;
-class SwitchPlatform;
-typedef SwitchPlatform Platform;
 class SwitchThread;
 typedef SwitchThread Thread;
+class ClipboardBase;
+typedef ClipboardBase Clipboard;
+class SwitchPlatform;
+typedef SwitchPlatform Platform;
 class SwitchWindow;
 typedef SwitchWindow Window;
 class SwitchNetwork;
 typedef SwitchNetwork Network;
 class SwitchUser;
 typedef SwitchUser User;
+class ScreenUtilitiesBase;
+typedef ScreenUtilitiesBase ScreenUtilities;
 
 #elif PLATFORM_MAC
 
-class MacClipboard;
-typedef MacClipboard Clipboard;
 class UnixCriticalSection;
 typedef UnixCriticalSection CriticalSection;
 class UnixConditionVariable;
@@ -241,21 +261,23 @@ class MacFileSystemWatcher;
 typedef MacFileSystemWatcher FileSystemWatcher;
 class UnixFile;
 typedef UnixFile File;
-class MacPlatform;
-typedef MacPlatform Platform;
 class AppleThread;
 typedef AppleThread Thread;
+class MacClipboard;
+typedef MacClipboard Clipboard;
+class MacPlatform;
+typedef MacPlatform Platform;
 class MacWindow;
 typedef MacWindow Window;
 class UnixNetwork;
 typedef UnixNetwork Network;
 class UserBase;
 typedef UserBase User;
+class MacScreenUtilities;
+typedef MacScreenUtilities ScreenUtilities;
 
 #elif PLATFORM_IOS
 
-class ClipboardBase;
-typedef ClipboardBase Clipboard;
 class UnixCriticalSection;
 typedef UnixCriticalSection CriticalSection;
 class UnixConditionVariable;
@@ -266,19 +288,34 @@ class FileSystemWatcherBase;
 typedef FileSystemWatcherBase FileSystemWatcher;
 class iOSFile;
 typedef iOSFile File;
-class iOSPlatform;
-typedef iOSPlatform Platform;
 class AppleThread;
 typedef AppleThread Thread;
+class ClipboardBase;
+typedef ClipboardBase Clipboard;
+class iOSPlatform;
+typedef iOSPlatform Platform;
 class iOSWindow;
 typedef iOSWindow Window;
 class UnixNetwork;
 typedef UnixNetwork Network;
 class UserBase;
 typedef UserBase User;
+class ScreenUtilitiesBase;
+typedef ScreenUtilitiesBase ScreenUtilities;
 
 #else
 
 #error Missing Types implementation!
 
 #endif
+
+#if PLATFORM_SDL
+#if PLATFORM_LINUX
+class SDLClipboard;
+typedef SDLClipboard Clipboard;
+#endif
+class SDLPlatform;
+typedef SDLPlatform Platform;
+class SDLWindow;
+typedef SDLWindow Window;
+#endif

Source/Engine/Platform/Window.cs

@@ -17,31 +17,37 @@ namespace FlaxEngine
         /// <summary>
         /// Perform window hit test delegate.
         /// </summary>
-        /// <param name="mouse">The mouse position. The coordinate is relative to the upper-left corner of the screen. Use <see cref="ScreenToClient"/> to convert position into client space coordinates.</param>
+        /// <param name="mousePosition">The mouse position. The coordinate is relative to the upper-left corner of the screen. Use <see cref="ScreenToClient"/> to convert position into client space coordinates.</param>
         /// <returns>Hit result.</returns>
-        public delegate WindowHitCodes HitTestDelegate(ref Float2 mouse);
+        public delegate WindowHitCodes HitTestDelegate(ref Float2 mousePosition);
 
         /// <summary>
         /// Perform mouse buttons action.
         /// </summary>
-        /// <param name="mouse">The mouse position.</param>
+        /// <param name="mousePosition">The mouse position.</param>
         /// <param name="button">The mouse buttons state.</param>
         /// <param name="handled">The flag that indicated that event has been handled by the custom code and should not be passed further. By default it is set to false.</param>
-        public delegate void MouseButtonDelegate(ref Float2 mouse, MouseButton button, ref bool handled);
+        public delegate void MouseButtonDelegate(ref Float2 mousePosition, MouseButton button, ref bool handled);
 
         /// <summary>
         /// Perform mouse move action.
         /// </summary>
-        /// <param name="mouse">The mouse position.</param>
-        public delegate void MouseMoveDelegate(ref Float2 mouse);
+        /// <param name="mousePosition">The mouse position.</param>
+        public delegate void MouseMoveDelegate(ref Float2 mousePosition);
+        
+        /// <summary>
+        /// Perform mouse move action in relative mode.
+        /// </summary>
+        /// <param name="mouseMotion">The relative mouse motion.</param>
+        public delegate void MouseMoveRelativeDelegate(ref Float2 mouseMotion);
 
         /// <summary>
         /// Perform mouse wheel action.
         /// </summary>
-        /// <param name="mouse">The mouse position.</param>
+        /// <param name="mousePosition">The mouse position.</param>
         /// <param name="delta">The mouse wheel move delta (can be positive or negative; normalized to [-1;1] range).</param>
         /// <param name="handled">The flag that indicated that event has been handled by the custom code and should not be passed further. By default it is set to false.</param>
-        public delegate void MouseWheelDelegate(ref Float2 mouse, float delta, ref bool handled);
+        public delegate void MouseWheelDelegate(ref Float2 mousePosition, float delta, ref bool handled);
 
         /// <summary>
         /// Perform touch action.
@@ -99,9 +105,14 @@ namespace FlaxEngine
         public event MouseWheelDelegate MouseWheel;
 
         /// <summary>
-        /// Event fired when mouse moves
+        /// Event fired when mouse moves.
         /// </summary>
         public event MouseMoveDelegate MouseMove;
+        
+        /// <summary>
+        /// Event fired when mouse moves in relative mode.
+        /// </summary>
+        public event MouseMoveRelativeDelegate MouseMoveRelative;
 
         /// <summary>
         /// Event fired when mouse leaves window.
@@ -273,6 +284,12 @@ namespace FlaxEngine
             MouseMove?.Invoke(ref pos);
             GUI.OnMouseMove(pos);
         }
+        
+        internal void Internal_OnMouseMoveRelative(ref Float2 mouseMotion)
+        {
+            MouseMoveRelative?.Invoke(ref mouseMotion);
+            GUI.OnMouseMoveRelative(mouseMotion);
+        }
 
         internal void Internal_OnMouseLeave()
         {

Source/Engine/Platform/Window.h

@@ -2,7 +2,9 @@
 
 #pragma once
 
-#if PLATFORM_WINDOWS
+#if PLATFORM_SDL
+#include "SDL/SDLWindow.h"
+#elif PLATFORM_WINDOWS
 #include "Windows/WindowsWindow.h"
 #elif PLATFORM_UWP
 #include "UWP/UWPWindow.h"

Source/Engine/Platform/Windows/WindowsFileSystem.cpp

@@ -2,6 +2,7 @@
 
 #if PLATFORM_WINDOWS
 
+#include "WindowsWindow.h"
 #include "WindowsFileSystem.h"
 #include "Engine/Platform/File.h"
 #include "Engine/Platform/Window.h"
@@ -317,7 +318,7 @@ bool WindowsFileSystem::ShowBrowseFolderDialog(Window* parentWindow, const Strin
         if (SUCCEEDED(SHCreateItemFromParsingName(initialDirectory.Get(), NULL, IID_PPV_ARGS(&defaultFolder))))
             fd->SetFolder(defaultFolder);
 
-        HWND hwndOwner = parentWindow ? parentWindow->GetHWND() : NULL;
+        HWND hwndOwner = parentWindow ? (HWND)parentWindow->GetNativePtr() : NULL;
         if (SUCCEEDED(fd->Show(hwndOwner)))
         {
             ComPtr<IShellItem> si;

Source/Engine/Platform/Windows/WindowsInput.cpp

@@ -1,6 +1,6 @@
 // Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
 
-#if PLATFORM_WINDOWS
+#if PLATFORM_WINDOWS && !PLATFORM_SDL
 
 #include "WindowsInput.h"
 #include "WindowsWindow.h"
@@ -265,19 +265,38 @@ bool WindowsMouse::WndProc(Window* window, const UINT msg, WPARAM wParam, LPARAM
     }
     case WM_LBUTTONDBLCLK:
     {
-        OnMouseDoubleClick(mousePos, MouseButton::Left, window);
+        if (!Input::Mouse->IsRelative())
+            OnMouseDoubleClick(mousePos, MouseButton::Left, window);
+        else
+            OnMouseDown(mousePos, MouseButton::Left, window);
         result = true;
         break;
     }
     case WM_RBUTTONDBLCLK:
     {
-        OnMouseDoubleClick(mousePos, MouseButton::Right, window);
+        if (!Input::Mouse->IsRelative())
+            OnMouseDoubleClick(mousePos, MouseButton::Right, window);
+        else
+            OnMouseDown(mousePos, MouseButton::Right, window);
         result = true;
         break;
     }
     case WM_MBUTTONDBLCLK:
     {
-        OnMouseDoubleClick(mousePos, MouseButton::Middle, window);
+        if (!Input::Mouse->IsRelative())
+            OnMouseDoubleClick(mousePos, MouseButton::Middle, window);
+        else
+            OnMouseDown(mousePos, MouseButton::Middle, window);
+        result = true;
+        break;
+    }
+    case WM_XBUTTONDBLCLK:
+    {
+        const auto button = (HIWORD(wParam) & XBUTTON1) ? MouseButton::Extended1 : MouseButton::Extended2;
+        if (!Input::Mouse->IsRelative())
+            OnMouseDoubleClick(mousePos, button, window);
+        else
+            OnMouseDown(mousePos, button, window);
         result = true;
         break;
     }

Source/Engine/Platform/Windows/WindowsPlatform.cpp

@@ -4,6 +4,8 @@
 
 #include "Engine/Platform/Platform.h"
 #include "Engine/Platform/Window.h"
+#include "Engine/Platform/Windows/WindowsInput.h"
+#include "Engine/Platform/Windows/WindowsWindow.h"
 #include "Engine/Platform/FileSystem.h"
 #include "Engine/Platform/CreateWindowSettings.h"
 #include "Engine/Platform/CreateProcessSettings.h"
@@ -33,7 +35,6 @@
 #define CLR_EXCEPTION 0xE0434352
 #define VCPP_EXCEPTION 0xE06D7363
 
-const Char* WindowsPlatform::ApplicationWindowClass = TEXT("FlaxWindow");
 void* WindowsPlatform::Instance = nullptr;
 
 #if CRASH_LOG_ENABLE || TRACY_ENABLE
@@ -256,6 +257,8 @@ void GetWindowsVersion(String& windowsName, int32& versionMajor, int32& versionM
     RegCloseKey(hKey);
 }
 
+#if !PLATFORM_SDL
+
 LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
 {
     // Find window to process that message
@@ -273,6 +276,8 @@ LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
     return DefWindowProc(hwnd, msg, wParam, lParam);
 }
 
+#endif
+
 long __stdcall WindowsPlatform::SehExceptionHandler(EXCEPTION_POINTERS* ep)
 {
     if (ep->ExceptionRecord->ExceptionCode == CLR_EXCEPTION)
@@ -437,11 +442,12 @@ DialogResult MessageBox::Show(Window* parent, const StringView& text, const Stri
         flags |= MB_ICONHAND;
         break;
     case MessageBoxIcon::Information:
+    case MessageBoxIcon::Question:
         flags |= MB_ICONINFORMATION;
         break;
-    case MessageBoxIcon::Question:
-        flags |= MB_ICONQUESTION;
-        break;
+    //case MessageBoxIcon::Question:
+    //    flags |= MB_ICONQUESTION;
+    //    break;
     case MessageBoxIcon::Stop:
         flags |= MB_ICONSTOP;
         break;
@@ -519,6 +525,7 @@ void WindowsPlatform::PreInit(void* hInstance)
     // Disable the process from being showing "ghosted" while not responding messages during slow tasks
     DisableProcessWindowsGhosting();
 
+#if !PLATFORM_SDL
     // Register window class
     WNDCLASS windowsClass;
     Platform::MemoryClear(&windowsClass, sizeof(WNDCLASS));
@@ -527,12 +534,13 @@ void WindowsPlatform::PreInit(void* hInstance)
     windowsClass.hInstance = (HINSTANCE)Instance;
     windowsClass.hIcon = LoadIconW(GetModuleHandle(nullptr), MAKEINTRESOURCE(IDR_MAINFRAME));
     windowsClass.hCursor = LoadCursor(nullptr, IDC_ARROW);
-    windowsClass.lpszClassName = ApplicationWindowClass;
+    windowsClass.lpszClassName = ApplicationClassName;
     if (!RegisterClassW(&windowsClass))
     {
         Error(TEXT("Window class registration failed!"));
         exit(-1);
     }
+#endif
 
     // Init OLE
     if (OleInitialize(nullptr) != S_OK)
@@ -661,11 +669,13 @@ bool WindowsPlatform::Init()
     DWORD tmp;
     Char buffer[256];
 
+#if !PLATFORM_SDL
     // Get user locale string
     if (GetUserDefaultLocaleName(buffer, LOCALE_NAME_MAX_LENGTH))
     {
         UserLocale = String(buffer);
     }
+#endif
 
     // Get computer name string
     if (GetComputerNameW(buffer, &tmp))
@@ -681,7 +691,9 @@ bool WindowsPlatform::Init()
     }
     OnPlatformUserAdd(New<User>(userName));
 
+#if !PLATFORM_SDL
     WindowsInput::Init();
+#endif
 
     return false;
 }
@@ -709,7 +721,9 @@ void WindowsPlatform::LogInfo()
 
 void WindowsPlatform::Tick()
 {
+#if !PLATFORM_SDL
     WindowsInput::Update();
+#endif
 
     // Check to see if any messages are waiting in the queue
     MSG msg;
@@ -740,8 +754,10 @@ void WindowsPlatform::Exit()
     DbgHelpUnlock();
 #endif
 
+#if !PLATFORM_SDL
     // Unregister app class
-    UnregisterClassW(ApplicationWindowClass, nullptr);
+    UnregisterClassW(ApplicationClassName, nullptr);
+#endif
 
     Win32Platform::Exit();
 }
@@ -808,6 +824,7 @@ BatteryInfo WindowsPlatform::GetBatteryInfo()
     return info;
 }
 
+#if !PLATFORM_SDL
 int32 WindowsPlatform::GetDpi()
 {
     return SystemDpi;
@@ -817,6 +834,7 @@ String WindowsPlatform::GetUserLocaleName()
 {
     return UserLocale;
 }
+#endif
 
 String WindowsPlatform::GetComputerName()
 {
@@ -1186,10 +1204,12 @@ int32 WindowsPlatform::CreateProcess(CreateProcessSettings& settings)
     return result;
 }
 
+#if !PLATFORM_SDL
 Window* WindowsPlatform::CreateWindow(const CreateWindowSettings& settings)
 {
     return New<WindowsWindow>(settings);
 }
+#endif
 
 void* WindowsPlatform::LoadLibrary(const Char* filename)
 {

Source/Engine/Platform/Windows/WindowsPlatform.h

@@ -13,11 +13,6 @@ class FLAXENGINE_API WindowsPlatform : public Win32Platform
 {
 public:
 
-    /// <summary>
-    /// Win32 application windows class name.
-    /// </summary>
-    static const Char* ApplicationWindowClass;
-
     /// <summary>
     /// Handle to Win32 application instance.
     /// </summary>
@@ -68,8 +63,10 @@ public:
 #endif
     static void SetHighDpiAwarenessEnabled(bool enable);
     static BatteryInfo GetBatteryInfo();
+#if !PLATFORM_SDL
     static int32 GetDpi();
     static String GetUserLocaleName();
+#endif
     static String GetComputerName();
     static bool GetHasFocus();
     static bool CanOpenUrl(const StringView& url);
@@ -83,7 +80,9 @@ public:
     static bool GetEnvironmentVariable(const String& name, String& value);
     static bool SetEnvironmentVariable(const String& name, const String& value);
     static int32 CreateProcess(CreateProcessSettings& settings);
+#if !PLATFORM_SDL
     static Window* CreateWindow(const CreateWindowSettings& settings);
+#endif
     static void* LoadLibrary(const Char* filename);
 #if CRASH_LOG_ENABLE
     static Array<StackFrame, HeapAllocation> GetStackFrames(int32 skipCount = 0, int32 maxDepth = 60, void* context = nullptr);

Source/Engine/Platform/Windows/WindowsScreenUtilities.cpp

@@ -0,0 +1,54 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+#if USE_EDITOR && PLATFORM_WINDOWS
+
+#include "Engine/Platform/Types.h"
+#include "Engine/Platform/ScreenUtilities.h"
+#include "Engine/Core/Math/Vector2.h"
+#include "Engine/Core/Delegate.h"
+#include "Engine/Core/Log.h"
+#include "Engine/Profiler/ProfilerCPU.h"
+
+#include <Windows.h>
+
+#pragma comment(lib, "Gdi32.lib")
+
+Delegate<Color32> ScreenUtilitiesBase::PickColorDone;
+
+static HHOOK MouseCallbackHook;
+
+LRESULT CALLBACK OnScreenUtilsMouseCallback(_In_ int nCode, _In_ WPARAM wParam, _In_ LPARAM lParam)
+{
+    if (nCode >= 0 && wParam == WM_LBUTTONDOWN)
+    {
+        UnhookWindowsHookEx(MouseCallbackHook);
+
+        // Push event with the picked color
+        const Float2 cursorPos = Platform::GetMousePosition();
+        const Color32 colorPicked = ScreenUtilities::GetColorAt(cursorPos);
+        ScreenUtilities::PickColorDone(colorPicked);
+        return 1;
+    }
+    return CallNextHookEx(NULL, nCode, wParam, lParam);
+}
+
+Color32 WindowsScreenUtilities::GetColorAt(const Float2& pos)
+{
+    PROFILE_CPU();
+    HDC deviceContext = GetDC(NULL);
+    COLORREF color = GetPixel(deviceContext, (int)pos.X, (int)pos.Y);
+    ReleaseDC(NULL, deviceContext);
+    return Color32(GetRValue(color), GetGValue(color), GetBValue(color), 255);
+}
+
+void WindowsScreenUtilities::PickColor()
+{
+    MouseCallbackHook = SetWindowsHookEx(WH_MOUSE_LL, OnScreenUtilsMouseCallback, NULL, NULL);
+    if (MouseCallbackHook == NULL)
+    {
+        LOG(Warning, "Failed to set mouse hook.");
+        LOG(Warning, "Error: {0}", GetLastError());
+    }
+}
+
+#endif

Source/Engine/Platform/Windows/WindowsScreenUtilities.h

@@ -0,0 +1,25 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#if USE_EDITOR && PLATFORM_WINDOWS
+
+#include "Engine/Platform/Base/ScreenUtilitiesBase.h"
+#include "Engine/Core/Types/BaseTypes.h"
+#include "Engine/Core/Math/Color32.h"
+#include "Engine/Core/Math/Vector2.h"
+#include "Engine/Core/Delegate.h"
+
+/// <summary>
+/// Platform-dependent screen utilities.
+/// </summary>
+class FLAXENGINE_API WindowsScreenUtilities : public ScreenUtilitiesBase
+{
+public:
+    
+    // [ScreenUtilitiesBase]
+    static Color32 GetColorAt(const Float2& pos);
+    static void PickColor();
+};
+
+#endif

Source/Engine/Platform/Windows/WindowsWindow.DragDrop.cpp

@@ -0,0 +1,661 @@
+// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
+
+#if PLATFORM_WINDOWS
+
+#if PLATFORM_SDL
+#include "Engine/Platform/SDL/SDLWindow.h"
+#endif
+
+#include "Engine/Platform/Windows/WindowsWindow.h"
+
+#if USE_EDITOR
+#include "Engine/Core/Collections/Array.h"
+#include "Engine/Platform/IGuiData.h"
+#include "Engine/Platform/Base/DragDropHelper.h"
+#include "Engine/Input/Input.h"
+#include "Engine/Input/Mouse.h"
+#endif
+#include "../Win32/IncludeWindowsHeaders.h"
+#include <propidl.h>
+#if USE_EDITOR
+#include <oleidl.h>
+#include <shellapi.h>
+#endif
+
+#if USE_EDITOR
+
+Windows::HRESULT Window::QueryInterface(const Windows::IID& id, void** ppvObject)
+{
+    // Check to see what interface has been requested
+    if ((const IID&)id == IID_IUnknown || (const IID&)id == IID_IDropTarget)
+    {
+        AddRef();
+        *ppvObject = this;
+        return S_OK;
+    }
+
+    // No interface
+    *ppvObject = nullptr;
+    return E_NOINTERFACE;
+}
+
+Windows::ULONG Window::AddRef()
+{
+    _InterlockedIncrement(&_refCount);
+    return _refCount;
+}
+
+Windows::ULONG Window::Release()
+{
+    return _InterlockedDecrement(&_refCount);
+}
+
+HGLOBAL duplicateGlobalMem(HGLOBAL hMem)
+{
+    auto len = GlobalSize(hMem);
+    auto source = GlobalLock(hMem);
+    auto dest = GlobalAlloc(GMEM_FIXED, len);
+    Platform::MemoryCopy(dest, source, len);
+    GlobalUnlock(hMem);
+    return dest;
+}
+
+DWORD dropEffect2OleEnum(DragDropEffect effect)
+{
+    DWORD result;
+    switch (effect)
+    {
+    case DragDropEffect::None:
+        result = DROPEFFECT_NONE;
+        break;
+    case DragDropEffect::Copy:
+        result = DROPEFFECT_COPY;
+        break;
+    case DragDropEffect::Move:
+        result = DROPEFFECT_MOVE;
+        break;
+    case DragDropEffect::Link:
+        result = DROPEFFECT_LINK;
+        break;
+    default:
+        result = DROPEFFECT_NONE;
+        break;
+    }
+    return result;
+}
+
+DragDropEffect dropEffectFromOleEnum(DWORD effect)
+{
+    DragDropEffect result;
+    switch (effect)
+    {
+    case DROPEFFECT_NONE:
+        result = DragDropEffect::None;
+        break;
+    case DROPEFFECT_COPY:
+        result = DragDropEffect::Copy;
+        break;
+    case DROPEFFECT_MOVE:
+        result = DragDropEffect::Move;
+        break;
+    case DROPEFFECT_LINK:
+        result = DragDropEffect::Link;
+        break;
+    default:
+        result = DragDropEffect::None;
+        break;
+    }
+    return result;
+}
+
+HANDLE StringToHandle(const StringView& str)
+{
+    // Allocate and lock a global memory buffer.
+    // Make it fixed data so we don't have to use GlobalLock
+    const int32 length = str.Length();
+    char* ptr = static_cast<char*>(GlobalAlloc(GMEM_FIXED, length + 1));
+
+    // Copy the string into the buffer as ANSI text
+    StringUtils::ConvertUTF162ANSI(str.Get(), ptr, length);
+    ptr[length] = '\0';
+
+    return ptr;
+}
+
+void DeepCopyFormatEtc(FORMATETC* dest, FORMATETC* source)
+{
+    // Copy the source FORMATETC into dest
+    *dest = *source;
+
+    if (source->ptd)
+    {
+        // Allocate memory for the DVTARGETDEVICE if necessary
+        dest->ptd = static_cast<DVTARGETDEVICE*>(CoTaskMemAlloc(sizeof(DVTARGETDEVICE)));
+
+        // Copy the contents of the source DVTARGETDEVICE into dest->ptd
+        *(dest->ptd) = *(source->ptd);
+    }
+}
+
+HRESULT CreateEnumFormatEtc(UINT nNumFormats, FORMATETC* pFormatEtc, IEnumFORMATETC** ppEnumFormatEtc);
+
+/// <summary>
+/// GUI data for Windows platform
+/// </summary>
+class WindowsGuiData : public IGuiData
+{
+private:
+    Type _type;
+    Array<String> _data;
+
+public:
+    /// <summary>
+    /// Init
+    /// </summary>
+    WindowsGuiData()
+        : _type(Type::Unknown)
+        , _data(1)
+    {
+    }
+
+public:
+    /// <summary>
+    /// Init from Ole IDataObject
+    /// </summary>
+    /// <param name="pDataObj">Object</param>
+    void Init(IDataObject* pDataObj)
+    {
+        // Temporary data
+        FORMATETC fmtetc;
+        STGMEDIUM stgmed;
+
+        // Clear
+        _type = Type::Unknown;
+        _data.Clear();
+
+        // Check type
+        fmtetc = { CF_TEXT, nullptr, DVASPECT_CONTENT, -1, TYMED_HGLOBAL };
+        if (pDataObj->GetData(&fmtetc, &stgmed) == S_OK)
+        {
+            // Text
+            _type = Type::Text;
+
+            // Get data
+            char* text = static_cast<char*>(GlobalLock(stgmed.hGlobal));
+            _data.Add(String(text));
+            GlobalUnlock(stgmed.hGlobal);
+            ReleaseStgMedium(&stgmed);
+        }
+        else
+        {
+            fmtetc = { CF_UNICODETEXT, nullptr, DVASPECT_CONTENT, -1, TYMED_HGLOBAL };
+            if (pDataObj->GetData(&fmtetc, &stgmed) == S_OK)
+            {
+                // Unicode Text
+                _type = Type::Text;
+
+                // Get data
+                Char* text = static_cast<Char*>(GlobalLock(stgmed.hGlobal));
+                _data.Add(String(text));
+                GlobalUnlock(stgmed.hGlobal);
+                ReleaseStgMedium(&stgmed);
+            }
+            else
+            {
+                fmtetc = { CF_HDROP, nullptr, DVASPECT_CONTENT, -1, TYMED_HGLOBAL };
+                if (pDataObj->GetData(&fmtetc, &stgmed) == S_OK)
+                {
+                    // Files
+                    _type = Type::Files;
+
+                    // Get data
+                    Char item[MAX_PATH];
+                    HDROP hdrop = static_cast<HDROP>(GlobalLock(stgmed.hGlobal));
+                    UINT filesCount = DragQueryFileW(hdrop, 0xFFFFFFFF, nullptr, 0);
+                    for (UINT i = 0; i < filesCount; i++)
+                    {
+                        if (DragQueryFileW(hdrop, i, item, MAX_PATH) != 0)
+                        {
+                            _data.Add(String(item));
+                        }
+                    }
+                    GlobalUnlock(stgmed.hGlobal);
+                    ReleaseStgMedium(&stgmed);
+                }
+            }
+        }
+    }
+
+public:
+    // [IGuiData]
+    Type GetType() const override
+    {
+        return _type;
+    }
+    String GetAsText() const override
+    {
+        String result;
+        if (_type == Type::Text)
+        {
+            result = _data[0];
+        }
+        return result;
+    }
+    void GetAsFiles(Array<String>* files) const override
+    {
+        if (_type == Type::Files)
+        {
+            files->Add(_data);
+        }
+    }
+};
+
+/// <summary>
+/// Tool class for Windows Ole support
+/// </summary>
+class WindowsEnumFormatEtc : public IEnumFORMATETC
+{
+private:
+    ULONG _refCount;
+    ULONG _index;
+    ULONG _formatsCount;
+    FORMATETC* _formatEtc;
+
+public:
+    WindowsEnumFormatEtc(FORMATETC* pFormatEtc, int32 nNumFormats)
+        : _refCount(1)
+        , _index(0)
+        , _formatsCount(nNumFormats)
+        , _formatEtc(nullptr)
+    {
+        // Allocate memory
+        _formatEtc = new FORMATETC[nNumFormats];
+
+        // Copy the FORMATETC structures
+        for (int32 i = 0; i < nNumFormats; i++)
+        {
+            DeepCopyFormatEtc(&_formatEtc[i], &pFormatEtc[i]);
+        }
+    }
+
+    ~WindowsEnumFormatEtc()
+    {
+        if (_formatEtc)
+        {
+            for (uint32 i = 0; i < _formatsCount; i++)
+            {
+                if (_formatEtc[i].ptd)
+                {
+                    CoTaskMemFree(_formatEtc[i].ptd);
+                }
+            }
+
+            delete[] _formatEtc;
+        }
+    }
+
+public:
+    HRESULT STDMETHODCALLTYPE QueryInterface(REFIID riid, _COM_Outptr_ void __RPC_FAR* __RPC_FAR* ppvObject) override
+    {
+        // Check to see what interface has been requested
+        if (riid == IID_IEnumFORMATETC || riid == IID_IUnknown)
+        {
+            AddRef();
+            *ppvObject = this;
+            return S_OK;
+        }
+
+        // No interface
+        *ppvObject = nullptr;
+        return E_NOINTERFACE;
+    }
+    ULONG STDMETHODCALLTYPE AddRef() override
+    {
+        _InterlockedIncrement(&_refCount);
+        return _refCount;
+    }
+    ULONG STDMETHODCALLTYPE Release() override
+    {
+        ULONG ulRefCount = _InterlockedDecrement(&_refCount);
+        if (_refCount == 0)
+        {
+            delete this;
+        }
+        return ulRefCount;
+    }
+
+    // [IEnumFormatEtc]
+    HRESULT STDMETHODCALLTYPE Next(ULONG celt, FORMATETC* pFormatEtc, ULONG* pceltFetched) override
+    {
+        ULONG copied = 0;
+
+        // validate arguments
+        if (celt == 0 || pFormatEtc == nullptr)
+            return E_INVALIDARG;
+
+        // copy FORMATETC structures into caller's buffer
+        while (_index < _formatsCount && copied < celt)
+        {
+            DeepCopyFormatEtc(&pFormatEtc[copied], &_formatEtc[_index]);
+            copied++;
+            _index++;
+        }
+
+        // store result
+        if (pceltFetched != nullptr)
+            *pceltFetched = copied;
+
+        // did we copy all that was requested?
+        return (copied == celt) ? S_OK : S_FALSE;
+    }
+    HRESULT STDMETHODCALLTYPE Skip(ULONG celt) override
+    {
+        _index += celt;
+        return (_index <= _formatsCount) ? S_OK : S_FALSE;
+    }
+    HRESULT STDMETHODCALLTYPE Reset() override
+    {
+        _index = 0;
+        return S_OK;
+    }
+    HRESULT STDMETHODCALLTYPE Clone(IEnumFORMATETC** ppEnumFormatEtc) override
+    {
+        HRESULT result;
+
+        // Make a duplicate enumerator
+        result = CreateEnumFormatEtc(_formatsCount, _formatEtc, ppEnumFormatEtc);
+
+        if (result == S_OK)
+        {
+            // Manually set the index state
+            static_cast<WindowsEnumFormatEtc*>(*ppEnumFormatEtc)->_index = _index;
+        }
+
+        return result;
+    }
+};
+
+HRESULT CreateEnumFormatEtc(UINT nNumFormats, FORMATETC* pFormatEtc, IEnumFORMATETC** ppEnumFormatEtc)
+{
+    if (nNumFormats == 0 || pFormatEtc == nullptr || ppEnumFormatEtc == nullptr)
+        return E_INVALIDARG;
+    *ppEnumFormatEtc = new WindowsEnumFormatEtc(pFormatEtc, nNumFormats);
+    return *ppEnumFormatEtc ? S_OK : E_OUTOFMEMORY;
+}
+
+/// <summary>
+/// Drag drop source and data container for Ole
+/// </summary>
+class WindowsDragSource : public IDataObject, public IDropSource
+{
+private:
+    ULONG _refCount;
+    int32 _formatsCount;
+    FORMATETC* _formatEtc;
+    STGMEDIUM* _stgMedium;
+
+public:
+    WindowsDragSource(FORMATETC* fmtetc, STGMEDIUM* stgmed, int32 count)
+        : _refCount(1)
+        , _formatsCount(count)
+        , _formatEtc(nullptr)
+        , _stgMedium(nullptr)
+    {
+        // Allocate memory
+        _formatEtc = new FORMATETC[count];
+        _stgMedium = new STGMEDIUM[count];
+
+        // Copy descriptors
+        for (int32 i = 0; i < count; i++)
+        {
+            _formatEtc[i] = fmtetc[i];
+            _stgMedium[i] = stgmed[i];
+        }
+    }
+
+    virtual ~WindowsDragSource()
+    {
+        delete[] _formatEtc;
+        delete[] _stgMedium;
+    }
+
+public:
+    // [IUnknown]
+    HRESULT STDMETHODCALLTYPE QueryInterface(REFIID riid, _COM_Outptr_ void __RPC_FAR* __RPC_FAR* ppvObject) override
+    {
+        // Check to see what interface has been requested
+        if (riid == IID_IDataObject || riid == IID_IUnknown || riid == IID_IDropSource)
+        {
+            AddRef();
+            *ppvObject = this;
+            return S_OK;
+        }
+
+        // No interface
+        *ppvObject = nullptr;
+        return E_NOINTERFACE;
+    }
+
+    ULONG STDMETHODCALLTYPE AddRef() override
+    {
+        _InterlockedIncrement(&_refCount);
+        return _refCount;
+    }
+
+    ULONG STDMETHODCALLTYPE Release() override
+    {
+        ULONG ulRefCount = _InterlockedDecrement(&_refCount);
+        if (_refCount == 0)
+        {
+            delete this;
+        }
+        return ulRefCount;
+    }
+
+    // [IDropSource]
+    HRESULT STDMETHODCALLTYPE QueryContinueDrag(_In_ BOOL fEscapePressed, _In_ DWORD grfKeyState) override
+    {
+        // If the Escape key has been pressed since the last call, cancel the drop
+        if (fEscapePressed == TRUE || grfKeyState & MK_RBUTTON)
+            return DRAGDROP_S_CANCEL;
+
+        // If the LeftMouse button has been released, then do the drop!
+        if ((grfKeyState & MK_LBUTTON) == 0)
+            return DRAGDROP_S_DROP;
+
+        // Continue with the drag-drop
+        return S_OK;
+    }
+    HRESULT STDMETHODCALLTYPE GiveFeedback(_In_ DWORD dwEffect) override
+    {
+        // TODO: allow to use custom mouse cursor during drop and drag operation
+        return DRAGDROP_S_USEDEFAULTCURSORS;
+    }
+
+    // [IDataObject]
+    HRESULT STDMETHODCALLTYPE GetData(_In_ FORMATETC* pformatetcIn, _Out_ STGMEDIUM* pmedium) override
+    {
+        if (pformatetcIn == nullptr || pmedium == nullptr)
+            return E_INVALIDARG;
+
+        // Try to match the specified FORMATETC with one of our supported formats
+        int32 index = lookupFormatEtc(pformatetcIn);
+        if (index == INVALID_INDEX)
+            return DV_E_FORMATETC;
+
+        // Found a match - transfer data into supplied storage medium
+        pmedium->tymed = _formatEtc[index].tymed;
+        pmedium->pUnkForRelease = nullptr;
+
+        // Copy the data into the caller's storage medium
+        switch (_formatEtc[index].tymed)
+        {
+        case TYMED_HGLOBAL:
+            pmedium->hGlobal = duplicateGlobalMem(_stgMedium[index].hGlobal);
+            break;
+
+        default:
+            return DV_E_FORMATETC;
+        }
+
+        return S_OK;
+    }
+    HRESULT STDMETHODCALLTYPE GetDataHere(_In_ FORMATETC* pformatetc, _Inout_ STGMEDIUM* pmedium) override
+    {
+        return DATA_E_FORMATETC;
+    }
+    HRESULT STDMETHODCALLTYPE QueryGetData(__RPC__in_opt FORMATETC* pformatetc) override
+    {
+        return lookupFormatEtc(pformatetc) == INVALID_INDEX ? DV_E_FORMATETC : S_OK;
+    }
+    HRESULT STDMETHODCALLTYPE GetCanonicalFormatEtc(__RPC__in_opt FORMATETC* pformatectIn, __RPC__out FORMATETC* pformatetcOut) override
+    {
+        // Apparently we have to set this field to NULL even though we don't do anything else
+        pformatetcOut->ptd = nullptr;
+        return E_NOTIMPL;
+    }
+    HRESULT STDMETHODCALLTYPE SetData(_In_ FORMATETC* pformatetc, _In_ STGMEDIUM* pmedium, BOOL fRelease) override
+    {
+        return E_NOTIMPL;
+    }
+    HRESULT STDMETHODCALLTYPE EnumFormatEtc(DWORD dwDirection, __RPC__deref_out_opt IEnumFORMATETC** ppenumFormatEtc) override
+    {
+        // Only the get direction is supported for OLE
+        if (dwDirection == DATADIR_GET)
+        {
+            // TODO: use SHCreateStdEnumFmtEtc API call
+            return CreateEnumFormatEtc(_formatsCount, _formatEtc, ppenumFormatEtc);
+        }
+
+        // The direction specified is not supported for drag+drop
+        return E_NOTIMPL;
+    }
+    HRESULT STDMETHODCALLTYPE DAdvise(__RPC__in FORMATETC* pformatetc, DWORD advf, __RPC__in_opt IAdviseSink* pAdvSink, __RPC__out DWORD* pdwConnection) override
+    {
+        return OLE_E_ADVISENOTSUPPORTED;
+    }
+    HRESULT STDMETHODCALLTYPE DUnadvise(DWORD dwConnection) override
+    {
+        return OLE_E_ADVISENOTSUPPORTED;
+    }
+    HRESULT STDMETHODCALLTYPE EnumDAdvise(__RPC__deref_out_opt IEnumSTATDATA** ppenumAdvise) override
+    {
+        return OLE_E_ADVISENOTSUPPORTED;
+    }
+
+private:
+    int32 lookupFormatEtc(FORMATETC* pFormatEtc) const
+    {
+        // Check each of our formats in turn to see if one matches
+        for (int32 i = 0; i < _formatsCount; i++)
+        {
+            if ((_formatEtc[i].tymed & pFormatEtc->tymed) &&
+                _formatEtc[i].cfFormat == pFormatEtc->cfFormat &&
+                _formatEtc[i].dwAspect == pFormatEtc->dwAspect)
+            {
+                // Return index of stored format
+                return i;
+            }
+        }
+
+        // Format not found
+        return INVALID_INDEX;
+    }
+};
+
+WindowsGuiData GuiDragDropData;
+
+DragDropEffect Window::DoDragDrop(const StringView& data)
+{
+    // Create background worker that will keep updating GUI (perform rendering)
+    const auto task = New<DoDragDropJob>();
+    Task::StartNew(task);
+    while (task->GetState() == TaskState::Queued)
+        Platform::Sleep(1);
+
+    // Create descriptors
+    FORMATETC fmtetc = { CF_TEXT, nullptr, DVASPECT_CONTENT, -1, TYMED_HGLOBAL };
+    STGMEDIUM stgmed = { TYMED_HGLOBAL, { nullptr }, nullptr };
+
+    // Create a HGLOBAL inside the storage medium
+    stgmed.hGlobal = StringToHandle(data);
+
+    // Create drop source
+    auto dropSource = new WindowsDragSource(&fmtetc, &stgmed, 1);
+
+    // Do the drag drop operation
+    DWORD dwEffect;
+    HRESULT result = ::DoDragDrop(dropSource, dropSource, DROPEFFECT_COPY | DROPEFFECT_MOVE | DROPEFFECT_LINK | DROPEFFECT_SCROLL, &dwEffect);
+
+    // Wait for job end
+    Platform::AtomicStore(&task->ExitFlag, 1);
+    task->Wait();
+
+    // Release allocated data
+    dropSource->Release();
+    ReleaseStgMedium(&stgmed);
+
+    // Fix hanging mouse state (Windows doesn't send WM_LBUTTONUP when we end the drag and drop)
+    if (Input::GetMouseButton(MouseButton::Left))
+    {
+        ::POINT point;
+        ::GetCursorPos(&point);
+#if PLATFORM_SDL
+        Input::Mouse->OnMouseUp(Float2((float)point.x, (float)point.y), MouseButton::Left, (Window*)this);
+#else
+        Input::Mouse->OnMouseUp(Float2((float)point.x, (float)point.y), MouseButton::Left, this);
+#endif
+    }
+
+    return SUCCEEDED(result) ? dropEffectFromOleEnum(dwEffect) : DragDropEffect::None;
+}
+
+HRESULT Window::DragEnter(Windows::IDataObject* pDataObj, Windows::DWORD grfKeyState, Windows::POINTL pt, Windows::DWORD* pdwEffect)
+{
+    POINT p = { pt.x, pt.y };
+    ::ScreenToClient((HWND)_handle, &p);
+    GuiDragDropData.Init((IDataObject*)pDataObj);
+    DragDropEffect effect = DragDropEffect::None;
+    OnDragEnter(&GuiDragDropData, Float2(static_cast<float>(p.x), static_cast<float>(p.y)), effect);
+    Focus();
+    *pdwEffect = dropEffect2OleEnum(effect);
+    return S_OK;
+}
+
+HRESULT Window::DragOver(Windows::DWORD grfKeyState, Windows::POINTL pt, Windows::DWORD* pdwEffect)
+{
+    POINT p = { pt.x, pt.y };
+    ::ScreenToClient((HWND)_handle, &p);
+    DragDropEffect effect = DragDropEffect::None;
+    OnDragOver(&GuiDragDropData, Float2(static_cast<float>(p.x), static_cast<float>(p.y)), effect);
+    *pdwEffect = dropEffect2OleEnum(effect);
+    return S_OK;
+}
+
+HRESULT Window::DragLeave()
+{
+    OnDragLeave();
+    return S_OK;
+}
+
+HRESULT Window::Drop(Windows::IDataObject* pDataObj, Windows::DWORD grfKeyState, Windows::POINTL pt, Windows::DWORD* pdwEffect)
+{
+    POINT p = { pt.x, pt.y };
+    ::ScreenToClient((HWND)_handle, &p);
+    GuiDragDropData.Init((IDataObject*)pDataObj);
+    DragDropEffect effect = DragDropEffect::None;
+    OnDragDrop(&GuiDragDropData, Float2(static_cast<float>(p.x), static_cast<float>(p.y)), effect);
+    *pdwEffect = dropEffect2OleEnum(effect);
+    return S_OK;
+}
+
+#else
+
+DragDropEffect Window::DoDragDrop(const StringView& data)
+{
+    return DragDropEffect::None;
+}
+
+#endif
+
+#endif

Source/Engine/Platform/Windows/WindowsWindow.cpp

@@ -1,6 +1,6 @@
 // Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
 
-#if PLATFORM_WINDOWS
+#if PLATFORM_WINDOWS && !PLATFORM_SDL
 
 #include "WindowsWindow.h"
 #include "WindowsPlatform.h"
@@ -10,13 +10,6 @@
 #include "Engine/Graphics/GPUSwapChain.h"
 #include "Engine/Graphics/RenderTask.h"
 #include "Engine/Graphics/GPUDevice.h"
-#if USE_EDITOR
-#include "Engine/Core/Collections/Array.h"
-#include "Engine/Platform/IGuiData.h"
-#include "Engine/Platform/Base/DragDropHelper.h"
-#include "Engine/Input/Input.h"
-#include "Engine/Input/Mouse.h"
-#endif
 #include "../Win32/IncludeWindowsHeaders.h"
 #include <propidl.h>
 #if USE_EDITOR
@@ -118,7 +111,7 @@ WindowsWindow::WindowsWindow(const CreateWindowSettings& settings)
         if (settings.IsRegularWindow)
             style |= WS_BORDER | WS_CAPTION | WS_DLGFRAME | WS_SYSMENU | WS_THICKFRAME | WS_GROUP;
 #elif WINDOWS_USE_NEWER_BORDER_LESS
-        if (settings.IsRegularWindow)
+        if (settings.Type == WindowType::Regular)
             style |= WS_THICKFRAME | WS_SYSMENU | WS_CAPTION;
 #endif
         exStyle |= WS_EX_WINDOWEDGE;
@@ -127,7 +120,7 @@ WindowsWindow::WindowsWindow(const CreateWindowSettings& settings)
     // Creating the window
     _handle = CreateWindowExW(
         exStyle,
-        Platform::ApplicationWindowClass,
+        Platform::ApplicationClassName,
         settings.Title.GetText(),
         style,
         x,
@@ -162,7 +155,7 @@ WindowsWindow::WindowsWindow(const CreateWindowSettings& settings)
 
 #if WINDOWS_USE_NEWER_BORDER_LESS
     // Enable shadow
-    if (_settings.IsRegularWindow && !_settings.HasBorder && IsCompositionEnabled())
+    if (settings.Type == WindowType::Regular && !_settings.HasBorder && IsCompositionEnabled())
     {
         const int margin[4] = { 1, 1, 1, 1 };
         ::DwmExtendFrameIntoClientArea(_handle, margin);
@@ -295,7 +288,7 @@ void WindowsWindow::SetBorderless(bool isBorderless, bool maximized)
         if (_settings.IsRegularWindow)
             style |= WS_BORDER | WS_CAPTION | WS_DLGFRAME | WS_SYSMENU | WS_THICKFRAME | WS_GROUP;
 #elif WINDOWS_USE_NEWER_BORDER_LESS
-        if (_settings.IsRegularWindow)
+        if (_settings.Type == WindowType::Regular)
             lStyle |= WS_THICKFRAME | WS_SYSMENU;
 #endif
 
@@ -371,7 +364,7 @@ void WindowsWindow::BringToFront(bool force)
 {
     ASSERT(HasHWND());
 
-    if (_settings.IsRegularWindow)
+    if (_settings.Type == WindowType::Regular)
     {
         if (IsIconic(_handle))
         {
@@ -698,36 +691,6 @@ void WindowsWindow::SetCursor(CursorType type)
     UpdateCursor();
 }
 
-#if USE_EDITOR
-
-Windows::HRESULT WindowsWindow::QueryInterface(const Windows::IID& id, void** ppvObject)
-{
-    // Check to see what interface has been requested
-    if ((const IID&)id == IID_IUnknown || (const IID&)id == IID_IDropTarget)
-    {
-        AddRef();
-        *ppvObject = this;
-        return S_OK;
-    }
-
-    // No interface
-    *ppvObject = nullptr;
-    return E_NOINTERFACE;
-}
-
-Windows::ULONG WindowsWindow::AddRef()
-{
-    _InterlockedIncrement(&_refCount);
-    return _refCount;
-}
-
-Windows::ULONG WindowsWindow::Release()
-{
-    return _InterlockedDecrement(&_refCount);
-}
-
-#endif
-
 void WindowsWindow::CheckForWindowResize()
 {
     // Skip for minimized window (GetClientRect for minimized window returns 0)
@@ -1345,617 +1308,11 @@ LRESULT WindowsWindow::WndProc(UINT msg, WPARAM wParam, LPARAM lParam)
 
     if (_settings.AllowInput)
     {
-        if (WindowsInput::WndProc(this, msg, wParam, lParam))
+        if (WindowsInput::WndProc((Window*)this, msg, wParam, lParam))
             return true;
     }
 
     return DefWindowProc(_handle, msg, wParam, lParam);
 }
 
-#if USE_EDITOR
-
-HGLOBAL duplicateGlobalMem(HGLOBAL hMem)
-{
-    auto len = GlobalSize(hMem);
-    auto source = GlobalLock(hMem);
-    auto dest = GlobalAlloc(GMEM_FIXED, len);
-    Platform::MemoryCopy(dest, source, len);
-    GlobalUnlock(hMem);
-    return dest;
-}
-
-DWORD dropEffect2OleEnum(DragDropEffect effect)
-{
-    DWORD result;
-    switch (effect)
-    {
-    case DragDropEffect::None:
-        result = DROPEFFECT_NONE;
-        break;
-    case DragDropEffect::Copy:
-        result = DROPEFFECT_COPY;
-        break;
-    case DragDropEffect::Move:
-        result = DROPEFFECT_MOVE;
-        break;
-    case DragDropEffect::Link:
-        result = DROPEFFECT_LINK;
-        break;
-    default:
-        result = DROPEFFECT_NONE;
-        break;
-    }
-    return result;
-}
-
-DragDropEffect dropEffectFromOleEnum(DWORD effect)
-{
-    DragDropEffect result;
-    switch (effect)
-    {
-    case DROPEFFECT_NONE:
-        result = DragDropEffect::None;
-        break;
-    case DROPEFFECT_COPY:
-        result = DragDropEffect::Copy;
-        break;
-    case DROPEFFECT_MOVE:
-        result = DragDropEffect::Move;
-        break;
-    case DROPEFFECT_LINK:
-        result = DragDropEffect::Link;
-        break;
-    default:
-        result = DragDropEffect::None;
-        break;
-    }
-    return result;
-}
-
-HANDLE StringToHandle(const StringView& str)
-{
-    // Allocate and lock a global memory buffer.
-    // Make it fixed data so we don't have to use GlobalLock
-    const int32 length = str.Length();
-    char* ptr = static_cast<char*>(GlobalAlloc(GMEM_FIXED, length + 1));
-
-    // Copy the string into the buffer as ANSI text
-    StringUtils::ConvertUTF162ANSI(str.Get(), ptr, length);
-    ptr[length] = '\0';
-
-    return ptr;
-}
-
-void DeepCopyFormatEtc(FORMATETC* dest, FORMATETC* source)
-{
-    // Copy the source FORMATETC into dest
-    *dest = *source;
-
-    if (source->ptd)
-    {
-        // Allocate memory for the DVTARGETDEVICE if necessary
-        dest->ptd = static_cast<DVTARGETDEVICE*>(CoTaskMemAlloc(sizeof(DVTARGETDEVICE)));
-
-        // Copy the contents of the source DVTARGETDEVICE into dest->ptd
-        *(dest->ptd) = *(source->ptd);
-    }
-}
-
-HRESULT CreateEnumFormatEtc(UINT nNumFormats, FORMATETC* pFormatEtc, IEnumFORMATETC** ppEnumFormatEtc);
-
-/// <summary>
-/// GUI data for Windows platform
-/// </summary>
-class WindowsGuiData : public IGuiData
-{
-private:
-    Type _type;
-    Array<String> _data;
-
-public:
-    /// <summary>
-    /// Init
-    /// </summary>
-    WindowsGuiData()
-        : _type(Type::Unknown)
-        , _data(1)
-    {
-    }
-
-public:
-    /// <summary>
-    /// Init from Ole IDataObject
-    /// </summary>
-    /// <param name="pDataObj">Object</param>
-    void Init(IDataObject* pDataObj)
-    {
-        // Temporary data
-        FORMATETC fmtetc;
-        STGMEDIUM stgmed;
-
-        // Clear
-        _type = Type::Unknown;
-        _data.Clear();
-
-        // Check type
-        fmtetc = { CF_TEXT, nullptr, DVASPECT_CONTENT, -1, TYMED_HGLOBAL };
-        if (pDataObj->GetData(&fmtetc, &stgmed) == S_OK)
-        {
-            // Text
-            _type = Type::Text;
-
-            // Get data
-            char* text = static_cast<char*>(GlobalLock(stgmed.hGlobal));
-            _data.Add(String(text));
-            GlobalUnlock(stgmed.hGlobal);
-            ReleaseStgMedium(&stgmed);
-        }
-        else
-        {
-            fmtetc = { CF_UNICODETEXT, nullptr, DVASPECT_CONTENT, -1, TYMED_HGLOBAL };
-            if (pDataObj->GetData(&fmtetc, &stgmed) == S_OK)
-            {
-                // Unicode Text
-                _type = Type::Text;
-
-                // Get data
-                Char* text = static_cast<Char*>(GlobalLock(stgmed.hGlobal));
-                _data.Add(String(text));
-                GlobalUnlock(stgmed.hGlobal);
-                ReleaseStgMedium(&stgmed);
-            }
-            else
-            {
-                fmtetc = { CF_HDROP, nullptr, DVASPECT_CONTENT, -1, TYMED_HGLOBAL };
-                if (pDataObj->GetData(&fmtetc, &stgmed) == S_OK)
-                {
-                    // Files
-                    _type = Type::Files;
-
-                    // Get data
-                    Char item[MAX_PATH];
-                    HDROP hdrop = static_cast<HDROP>(GlobalLock(stgmed.hGlobal));
-                    UINT filesCount = DragQueryFileW(hdrop, 0xFFFFFFFF, nullptr, 0);
-                    for (UINT i = 0; i < filesCount; i++)
-                    {
-                        if (DragQueryFileW(hdrop, i, item, MAX_PATH) != 0)
-                        {
-                            _data.Add(String(item));
-                        }
-                    }
-                    GlobalUnlock(stgmed.hGlobal);
-                    ReleaseStgMedium(&stgmed);
-                }
-            }
-        }
-    }
-
-public:
-    // [IGuiData]
-    Type GetType() const override
-    {
-        return _type;
-    }
-    String GetAsText() const override
-    {
-        String result;
-        if (_type == Type::Text)
-        {
-            result = _data[0];
-        }
-        return result;
-    }
-    void GetAsFiles(Array<String>* files) const override
-    {
-        if (_type == Type::Files)
-        {
-            files->Add(_data);
-        }
-    }
-};
-
-/// <summary>
-/// Tool class for Windows Ole support
-/// </summary>
-class WindowsEnumFormatEtc : public IEnumFORMATETC
-{
-private:
-    ULONG _refCount;
-    ULONG _index;
-    ULONG _formatsCount;
-    FORMATETC* _formatEtc;
-
-public:
-    WindowsEnumFormatEtc(FORMATETC* pFormatEtc, int32 nNumFormats)
-        : _refCount(1)
-        , _index(0)
-        , _formatsCount(nNumFormats)
-        , _formatEtc(nullptr)
-    {
-        // Allocate memory
-        _formatEtc = new FORMATETC[nNumFormats];
-
-        // Copy the FORMATETC structures
-        for (int32 i = 0; i < nNumFormats; i++)
-        {
-            DeepCopyFormatEtc(&_formatEtc[i], &pFormatEtc[i]);
-        }
-    }
-
-    ~WindowsEnumFormatEtc()
-    {
-        if (_formatEtc)
-        {
-            for (uint32 i = 0; i < _formatsCount; i++)
-            {
-                if (_formatEtc[i].ptd)
-                {
-                    CoTaskMemFree(_formatEtc[i].ptd);
-                }
-            }
-
-            delete[] _formatEtc;
-        }
-    }
-
-public:
-    HRESULT STDMETHODCALLTYPE QueryInterface(REFIID riid, _COM_Outptr_ void __RPC_FAR *__RPC_FAR * ppvObject) override
-    {
-        // Check to see what interface has been requested
-        if (riid == IID_IEnumFORMATETC || riid == IID_IUnknown)
-        {
-            AddRef();
-            *ppvObject = this;
-            return S_OK;
-        }
-
-        // No interface
-        *ppvObject = nullptr;
-        return E_NOINTERFACE;
-    }
-    ULONG STDMETHODCALLTYPE AddRef() override
-    {
-        _InterlockedIncrement(&_refCount);
-        return _refCount;
-    }
-    ULONG STDMETHODCALLTYPE Release() override
-    {
-        ULONG ulRefCount = _InterlockedDecrement(&_refCount);
-        if (_refCount == 0)
-        {
-            delete this;
-        }
-        return ulRefCount;
-    }
-
-    // [IEnumFormatEtc]
-    HRESULT STDMETHODCALLTYPE Next(ULONG celt, FORMATETC* pFormatEtc, ULONG* pceltFetched) override
-    {
-        ULONG copied = 0;
-
-        // validate arguments
-        if (celt == 0 || pFormatEtc == nullptr)
-            return E_INVALIDARG;
-
-        // copy FORMATETC structures into caller's buffer
-        while (_index < _formatsCount && copied < celt)
-        {
-            DeepCopyFormatEtc(&pFormatEtc[copied], &_formatEtc[_index]);
-            copied++;
-            _index++;
-        }
-
-        // store result
-        if (pceltFetched != nullptr)
-            *pceltFetched = copied;
-
-        // did we copy all that was requested?
-        return (copied == celt) ? S_OK : S_FALSE;
-    }
-    HRESULT STDMETHODCALLTYPE Skip(ULONG celt) override
-    {
-        _index += celt;
-        return (_index <= _formatsCount) ? S_OK : S_FALSE;
-    }
-    HRESULT STDMETHODCALLTYPE Reset() override
-    {
-        _index = 0;
-        return S_OK;
-    }
-    HRESULT STDMETHODCALLTYPE Clone(IEnumFORMATETC** ppEnumFormatEtc) override
-    {
-        HRESULT result;
-
-        // Make a duplicate enumerator
-        result = CreateEnumFormatEtc(_formatsCount, _formatEtc, ppEnumFormatEtc);
-
-        if (result == S_OK)
-        {
-            // Manually set the index state
-            static_cast<WindowsEnumFormatEtc*>(*ppEnumFormatEtc)->_index = _index;
-        }
-
-        return result;
-    }
-};
-
-HRESULT CreateEnumFormatEtc(UINT nNumFormats, FORMATETC* pFormatEtc, IEnumFORMATETC** ppEnumFormatEtc)
-{
-    if (nNumFormats == 0 || pFormatEtc == nullptr || ppEnumFormatEtc == nullptr)
-        return E_INVALIDARG;
-    *ppEnumFormatEtc = new WindowsEnumFormatEtc(pFormatEtc, nNumFormats);
-    return *ppEnumFormatEtc ? S_OK : E_OUTOFMEMORY;
-}
-
-/// <summary>
-/// Drag drop source and data container for Ole
-/// </summary>
-class WindowsDragSource : public IDataObject, public IDropSource
-{
-private:
-    ULONG _refCount;
-    int32 _formatsCount;
-    FORMATETC* _formatEtc;
-    STGMEDIUM* _stgMedium;
-
-public:
-    WindowsDragSource(FORMATETC* fmtetc, STGMEDIUM* stgmed, int32 count)
-        : _refCount(1)
-        , _formatsCount(count)
-        , _formatEtc(nullptr)
-        , _stgMedium(nullptr)
-    {
-        // Allocate memory
-        _formatEtc = new FORMATETC[count];
-        _stgMedium = new STGMEDIUM[count];
-
-        // Copy descriptors
-        for (int32 i = 0; i < count; i++)
-        {
-            _formatEtc[i] = fmtetc[i];
-            _stgMedium[i] = stgmed[i];
-        }
-    }
-
-    virtual ~WindowsDragSource()
-    {
-        delete[] _formatEtc;
-        delete[] _stgMedium;
-    }
-
-public:
-    // [IUnknown]
-    HRESULT STDMETHODCALLTYPE QueryInterface(REFIID riid, _COM_Outptr_ void __RPC_FAR *__RPC_FAR * ppvObject) override
-    {
-        // Check to see what interface has been requested
-        if (riid == IID_IDataObject || riid == IID_IUnknown || riid == IID_IDropSource)
-        {
-            AddRef();
-            *ppvObject = this;
-            return S_OK;
-        }
-
-        // No interface
-        *ppvObject = nullptr;
-        return E_NOINTERFACE;
-    }
-
-    ULONG STDMETHODCALLTYPE AddRef() override
-    {
-        _InterlockedIncrement(&_refCount);
-        return _refCount;
-    }
-
-    ULONG STDMETHODCALLTYPE Release() override
-    {
-        ULONG ulRefCount = _InterlockedDecrement(&_refCount);
-        if (_refCount == 0)
-        {
-            delete this;
-        }
-        return ulRefCount;
-    }
-
-    // [IDropSource]
-    HRESULT STDMETHODCALLTYPE QueryContinueDrag(_In_ BOOL fEscapePressed, _In_ DWORD grfKeyState) override
-    {
-        // If the Escape key has been pressed since the last call, cancel the drop
-        if (fEscapePressed == TRUE || grfKeyState & MK_RBUTTON)
-            return DRAGDROP_S_CANCEL;
-
-        // If the LeftMouse button has been released, then do the drop!
-        if ((grfKeyState & MK_LBUTTON) == 0)
-            return DRAGDROP_S_DROP;
-
-        // Continue with the drag-drop
-        return S_OK;
-    }
-    HRESULT STDMETHODCALLTYPE GiveFeedback(_In_ DWORD dwEffect) override
-    {
-        // TODO: allow to use custom mouse cursor during drop and drag operation
-        return DRAGDROP_S_USEDEFAULTCURSORS;
-    }
-
-    // [IDataObject]
-    HRESULT STDMETHODCALLTYPE GetData(_In_ FORMATETC* pformatetcIn, _Out_ STGMEDIUM* pmedium) override
-    {
-        if (pformatetcIn == nullptr || pmedium == nullptr)
-            return E_INVALIDARG;
-
-        // Try to match the specified FORMATETC with one of our supported formats
-        int32 index = lookupFormatEtc(pformatetcIn);
-        if (index == INVALID_INDEX)
-            return DV_E_FORMATETC;
-
-        // Found a match - transfer data into supplied storage medium
-        pmedium->tymed = _formatEtc[index].tymed;
-        pmedium->pUnkForRelease = nullptr;
-
-        // Copy the data into the caller's storage medium
-        switch (_formatEtc[index].tymed)
-        {
-        case TYMED_HGLOBAL:
-            pmedium->hGlobal = duplicateGlobalMem(_stgMedium[index].hGlobal);
-            break;
-
-        default:
-            return DV_E_FORMATETC;
-        }
-
-        return S_OK;
-    }
-    HRESULT STDMETHODCALLTYPE GetDataHere(_In_ FORMATETC* pformatetc, _Inout_ STGMEDIUM* pmedium) override
-    {
-        return DATA_E_FORMATETC;
-    }
-    HRESULT STDMETHODCALLTYPE QueryGetData(__RPC__in_opt FORMATETC* pformatetc) override
-    {
-        return lookupFormatEtc(pformatetc) == INVALID_INDEX ? DV_E_FORMATETC : S_OK;
-    }
-    HRESULT STDMETHODCALLTYPE GetCanonicalFormatEtc(__RPC__in_opt FORMATETC* pformatectIn, __RPC__out FORMATETC* pformatetcOut) override
-    {
-        // Apparently we have to set this field to NULL even though we don't do anything else
-        pformatetcOut->ptd = nullptr;
-        return E_NOTIMPL;
-    }
-    HRESULT STDMETHODCALLTYPE SetData(_In_ FORMATETC* pformatetc, _In_ STGMEDIUM* pmedium, BOOL fRelease) override
-    {
-        return E_NOTIMPL;
-    }
-    HRESULT STDMETHODCALLTYPE EnumFormatEtc(DWORD dwDirection, __RPC__deref_out_opt IEnumFORMATETC** ppenumFormatEtc) override
-    {
-        // Only the get direction is supported for OLE
-        if (dwDirection == DATADIR_GET)
-        {
-            // TODO: use SHCreateStdEnumFmtEtc API call
-            return CreateEnumFormatEtc(_formatsCount, _formatEtc, ppenumFormatEtc);
-        }
-
-        // The direction specified is not supported for drag+drop
-        return E_NOTIMPL;
-    }
-    HRESULT STDMETHODCALLTYPE DAdvise(__RPC__in FORMATETC* pformatetc, DWORD advf, __RPC__in_opt IAdviseSink* pAdvSink, __RPC__out DWORD* pdwConnection) override
-    {
-        return OLE_E_ADVISENOTSUPPORTED;
-    }
-    HRESULT STDMETHODCALLTYPE DUnadvise(DWORD dwConnection) override
-    {
-        return OLE_E_ADVISENOTSUPPORTED;
-    }
-    HRESULT STDMETHODCALLTYPE EnumDAdvise(__RPC__deref_out_opt IEnumSTATDATA** ppenumAdvise) override
-    {
-        return OLE_E_ADVISENOTSUPPORTED;
-    }
-
-private:
-    int32 lookupFormatEtc(FORMATETC* pFormatEtc) const
-    {
-        // Check each of our formats in turn to see if one matches
-        for (int32 i = 0; i < _formatsCount; i++)
-        {
-            if ((_formatEtc[i].tymed & pFormatEtc->tymed) &&
-                _formatEtc[i].cfFormat == pFormatEtc->cfFormat &&
-                _formatEtc[i].dwAspect == pFormatEtc->dwAspect)
-            {
-                // Return index of stored format
-                return i;
-            }
-        }
-
-        // Format not found
-        return INVALID_INDEX;
-    }
-};
-
-WindowsGuiData GuiDragDropData;
-
-DragDropEffect WindowsWindow::DoDragDrop(const StringView& data)
-{
-    // Create background worker that will keep updating GUI (perform rendering)
-    const auto task = New<DoDragDropJob>();
-    Task::StartNew(task);
-    while (task->GetState() == TaskState::Queued)
-        Platform::Sleep(1);
-
-    // Create descriptors
-    FORMATETC fmtetc = { CF_TEXT, nullptr, DVASPECT_CONTENT, -1, TYMED_HGLOBAL };
-    STGMEDIUM stgmed = { TYMED_HGLOBAL, { nullptr }, nullptr };
-
-    // Create a HGLOBAL inside the storage medium
-    stgmed.hGlobal = StringToHandle(data);
-
-    // Create drop source
-    auto dropSource = new WindowsDragSource(&fmtetc, &stgmed, 1);
-
-    // Do the drag drop operation
-    DWORD dwEffect;
-    HRESULT result = ::DoDragDrop(dropSource, dropSource, DROPEFFECT_COPY | DROPEFFECT_MOVE | DROPEFFECT_LINK | DROPEFFECT_SCROLL, &dwEffect);
-
-    // Wait for job end
-    Platform::AtomicStore(&task->ExitFlag, 1);
-    task->Wait();
-
-    // Release allocated data
-    dropSource->Release();
-    ReleaseStgMedium(&stgmed);
-
-    // Fix hanging mouse state (Windows doesn't send WM_LBUTTONUP when we end the drag and drop)
-    if (Input::GetMouseButton(MouseButton::Left))
-    {
-        ::POINT point;
-        ::GetCursorPos(&point);
-        Input::Mouse->OnMouseUp(Float2((float)point.x, (float)point.y), MouseButton::Left, this);
-    }
-
-    return SUCCEEDED(result) ? dropEffectFromOleEnum(dwEffect) : DragDropEffect::None;
-}
-
-HRESULT WindowsWindow::DragEnter(Windows::IDataObject* pDataObj, Windows::DWORD grfKeyState, Windows::POINTL pt, Windows::DWORD* pdwEffect)
-{
-    POINT p = { pt.x, pt.y };
-    ::ScreenToClient(_handle, &p);
-    GuiDragDropData.Init((IDataObject*)pDataObj);
-    DragDropEffect effect = DragDropEffect::None;
-    OnDragEnter(&GuiDragDropData, Float2(static_cast<float>(p.x), static_cast<float>(p.y)), effect);
-    Focus();
-    *pdwEffect = dropEffect2OleEnum(effect);
-    return S_OK;
-}
-
-HRESULT WindowsWindow::DragOver(Windows::DWORD grfKeyState, Windows::POINTL pt, Windows::DWORD* pdwEffect)
-{
-    POINT p = { pt.x, pt.y };
-    ::ScreenToClient(_handle, &p);
-    DragDropEffect effect = DragDropEffect::None;
-    OnDragOver(&GuiDragDropData, Float2(static_cast<float>(p.x), static_cast<float>(p.y)), effect);
-    *pdwEffect = dropEffect2OleEnum(effect);
-    return S_OK;
-}
-
-HRESULT WindowsWindow::DragLeave()
-{
-    OnDragLeave();
-    return S_OK;
-}
-
-HRESULT WindowsWindow::Drop(Windows::IDataObject* pDataObj, Windows::DWORD grfKeyState, Windows::POINTL pt, Windows::DWORD* pdwEffect)
-{
-    POINT p = { pt.x, pt.y };
-    ::ScreenToClient(_handle, &p);
-    GuiDragDropData.Init((IDataObject*)pDataObj);
-    DragDropEffect effect = DragDropEffect::None;
-    OnDragDrop(&GuiDragDropData, Float2(static_cast<float>(p.x), static_cast<float>(p.y)), effect);
-    *pdwEffect = dropEffect2OleEnum(effect);
-    return S_OK;
-}
-
-#else
-
-DragDropEffect WindowsWindow::DoDragDrop(const StringView& data)
-{
-	return DragDropEffect::None;
-}
-
-#endif
-
 #endif

Source/Engine/Platform/Windows/WindowsWindow.h

@@ -2,7 +2,7 @@
 
 #pragma once
 
-#if PLATFORM_WINDOWS
+#if PLATFORM_WINDOWS && !PLATFORM_SDL
 
 #include "Engine/Platform/Base/WindowBase.h"
 #include "Engine/Platform/Platform.h"
@@ -136,7 +136,7 @@ public:
     Windows::ULONG __stdcall AddRef() override;
     Windows::ULONG __stdcall Release() override;
 
-    // [IDropTarget]
+    // [Windows::IDropTarget]
     Windows::HRESULT __stdcall DragEnter(Windows::IDataObject* pDataObj, Windows::DWORD grfKeyState, Windows::POINTL pt, Windows::DWORD* pdwEffect) override;
     Windows::HRESULT __stdcall DragOver(Windows::DWORD grfKeyState, Windows::POINTL pt, Windows::DWORD* pdwEffect) override;
     Windows::HRESULT __stdcall DragLeave() override;

Source/Engine/UI/GUI/Control.cs

@@ -771,6 +771,15 @@ namespace FlaxEngine.GUI
                 Tooltip.OnMouseLeaveControl(this);
             }
         }
+        
+        /// <summary>
+        /// When mouse moves over control's area while mouse is in relative mode
+        /// </summary>
+        /// <param name="mouseMotion">Mouse relative motion</param>
+        [NoAnimate]
+        public virtual void OnMouseMoveRelative(Float2 mouseMotion)
+        {
+        }
 
         /// <summary>
         /// When mouse leaves control's area

Source/Engine/UI/GUI/Tooltip.cs

@@ -1,6 +1,7 @@
 // Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
 
 using System;
+using FlaxEditor;
 
 namespace FlaxEngine.GUI
 {
@@ -77,13 +78,17 @@ namespace FlaxEngine.GUI
             var dpiSize = Size * dpiScale;
             var locationWS = target.PointToWindow(location);
             var locationSS = parentWin.PointToScreen(locationWS);
+            var mousePos = Input.MouseScreenPosition;
             _showTarget = target;
-            WrapPosition(ref locationSS);
+            //WrapPosition(ref locationSS);
+            WrapPosition(ref mousePos, 10);
+            locationSS = mousePos;
 
             // Create window
             var desc = CreateWindowSettings.Default;
             desc.StartPosition = WindowStartPosition.Manual;
             desc.Position = locationSS;
+            //Editor.Log($"tooltip pos: {Input.MouseScreenPosition}, in parentloc: {location}");
             desc.Size = dpiSize;
             desc.Fullscreen = false;
             desc.HasBorder = false;
@@ -95,9 +100,11 @@ namespace FlaxEngine.GUI
             desc.AllowMaximize = false;
             desc.AllowDragAndDrop = false;
             desc.IsTopmost = true;
-            desc.IsRegularWindow = false;
+            desc.Type = WindowType.Tooltip;
+            desc.Title = "Tooltip";
             desc.HasSizingFrame = false;
             desc.ShowAfterFirstPaint = true;
+            desc.Parent = parentWin.RootWindow.Window;
             _window = Platform.CreateWindow(ref desc);
             if (_window == null)
                 throw new InvalidOperationException("Failed to create tooltip window.");
@@ -107,6 +114,7 @@ namespace FlaxEngine.GUI
             Visible = true;
             _window.Show();
             _showTarget.OnTooltipShown(this);
+            once = true;
         }
 
         /// <summary>
@@ -197,7 +205,7 @@ namespace FlaxEngine.GUI
             var rightBottomLocationSS = locationSS + dpiSize;
 
             // Prioritize tooltip placement within parent window, fall back to virtual desktop
-            if (rightBottomMonitorBounds.Y < rightBottomLocationSS.Y)
+            /*if (rightBottomMonitorBounds.Y < rightBottomLocationSS.Y)
             {
                 // Direction: up
                 locationSS.Y -= dpiSize.Y + flipOffset;
@@ -206,9 +214,11 @@ namespace FlaxEngine.GUI
             {
                 // Direction: left
                 locationSS.X -= dpiSize.X + flipOffset * 2;
-            }
+            }*/
         }
 
+        bool once = true;
+
         /// <inheritdoc />
         public override void Update(float deltaTime)
         {
@@ -219,12 +229,24 @@ namespace FlaxEngine.GUI
                 // Auto hide if mouse leaves control area
                 Hide();
             }
-            else
+            else if (true)
+            {
+                if (_window)
+                    _window.Position = _window.Position;
+
+                if (once)
+                {
+                    once = false;
+                    _window.ClientSize = _window.ClientSize + new Float2(2, 2);
+                }
+            }
+            else if (false)
             {
                 // Position tooltip when mouse moves
                 WrapPosition(ref mousePos, 10);
+                //Editor.Log($"tooltip newpos: {Input.MouseScreenPosition}, in parentloc: {location}");
                 if (_window)
-                    _window.Position = mousePos + new Float2(15, 10);
+                    _window.Position = mousePos;
             }
 
             base.Update(deltaTime);

Source/Engine/UI/GUI/WindowRootControl.cs

@@ -338,5 +338,17 @@ namespace FlaxEngine.GUI
 
             base.OnMouseMove(location);
         }
+
+        /// <inheritdoc />
+        public override void OnMouseMoveRelative(Float2 mouseMotion)
+        {
+            if (_trackingControl != null)
+            {
+                _trackingControl.OnMouseMoveRelative(mouseMotion);
+                return;
+            }
+
+            base.OnMouseMoveRelative(mouseMotion);
+        }
     }
 }

Source/ThirdParty/SDL/LICENSE.txt

@@ -0,0 +1,18 @@
+Copyright (C) 1997-2024 Sam Lantinga <slouken@libsdl.org>
+  
+This software is provided 'as-is', without any express or implied
+warranty.  In no event will the authors be held liable for any damages
+arising from the use of this software.
+
+Permission is granted to anyone to use this software for any purpose,
+including commercial applications, and to alter it and redistribute it
+freely, subject to the following restrictions:
+  
+1. The origin of this software must not be misrepresented; you must not
+   claim that you wrote the original software. If you use this software
+   in a product, an acknowledgment in the product documentation would be
+   appreciated but is not required. 
+2. Altered source versions must be plainly marked as such, and must not be
+   misrepresented as being the original software.
+3. This notice may not be removed or altered from any source distribution.
+

Source/ThirdParty/SDL/SDL.Build.cs

@@ -0,0 +1,53 @@
+// Copyright (c) 2012-2023 Wojciech Figat. All rights reserved.
+
+using System.IO;
+using Flax.Build;
+using Flax.Build.NativeCpp;
+
+/// <summary>
+/// https://www.libsdl.org/
+/// </summary>
+public class SDL : DepsModule
+{
+    /// <inheritdoc />
+    public override void Init()
+    {
+        base.Init();
+
+        LicenseType = LicenseTypes.Custom;
+        LicenseFilePath = "LICENSE.txt";
+
+        // Merge third-party modules into engine binary
+        BinaryModuleName = "FlaxEngine";
+    }
+
+    /// <inheritdoc />
+    public override void Setup(BuildOptions options)
+    {
+        base.Setup(options);
+
+        var depsRoot = options.DepsFolder;
+        switch (options.Platform.Target)
+        {
+        case TargetPlatform.Windows:
+            options.OutputFiles.Add(Path.Combine(depsRoot, "SDL3.lib"));
+            options.OptionalDependencyFiles.Add(Path.Combine(depsRoot, "SDL3.pdb"));
+            options.OptionalDependencyFiles.Add(Path.Combine(depsRoot, "SDL3.dll"));
+
+            // For static linkage
+            options.OutputFiles.Add("Setupapi.lib");
+            options.OutputFiles.Add("Version.lib");
+            options.OutputFiles.Add("Imm32.lib");
+            options.OutputFiles.Add("Gdi32.lib");
+
+            break;
+        case TargetPlatform.Linux:
+        case TargetPlatform.Mac:
+            options.OutputFiles.Add(Path.Combine(depsRoot, "libSDL3.a"));
+            break;
+        default: throw new InvalidPlatformException(options.Platform.Target);
+        }
+		
+		options.PublicIncludePaths.Add(Path.Combine(Globals.EngineRoot, @"Source\ThirdParty\SDL"));
+    }
+}

Source/ThirdParty/SDL/SDL3/SDL.h

@@ -0,0 +1,90 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2024 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+/**
+ * Main include header for the SDL library, version 3.1.7
+ *
+ * It is almost always best to include just this one header instead of
+ * picking out individual headers included here. There are exceptions to
+ * this rule--SDL_main.h is special and not included here--but usually
+ * letting SDL.h include the kitchen sink for you is the correct approach.
+ */
+
+#ifndef SDL_h_
+#define SDL_h_
+
+#include <SDL3/SDL_stdinc.h>
+#include <SDL3/SDL_assert.h>
+#include <SDL3/SDL_asyncio.h>
+#include <SDL3/SDL_atomic.h>
+#include <SDL3/SDL_audio.h>
+#include <SDL3/SDL_bits.h>
+#include <SDL3/SDL_blendmode.h>
+#include <SDL3/SDL_camera.h>
+#include <SDL3/SDL_clipboard.h>
+#include <SDL3/SDL_cpuinfo.h>
+#include <SDL3/SDL_dialog.h>
+#include <SDL3/SDL_endian.h>
+#include <SDL3/SDL_error.h>
+#include <SDL3/SDL_events.h>
+#include <SDL3/SDL_filesystem.h>
+#include <SDL3/SDL_gamepad.h>
+#include <SDL3/SDL_gpu.h>
+#include <SDL3/SDL_guid.h>
+#include <SDL3/SDL_haptic.h>
+#include <SDL3/SDL_hidapi.h>
+#include <SDL3/SDL_hints.h>
+#include <SDL3/SDL_init.h>
+#include <SDL3/SDL_iostream.h>
+#include <SDL3/SDL_joystick.h>
+#include <SDL3/SDL_keyboard.h>
+#include <SDL3/SDL_keycode.h>
+#include <SDL3/SDL_loadso.h>
+#include <SDL3/SDL_locale.h>
+#include <SDL3/SDL_log.h>
+#include <SDL3/SDL_messagebox.h>
+#include <SDL3/SDL_metal.h>
+#include <SDL3/SDL_misc.h>
+#include <SDL3/SDL_mouse.h>
+#include <SDL3/SDL_mutex.h>
+#include <SDL3/SDL_pen.h>
+#include <SDL3/SDL_pixels.h>
+#include <SDL3/SDL_platform.h>
+#include <SDL3/SDL_power.h>
+#include <SDL3/SDL_process.h>
+#include <SDL3/SDL_properties.h>
+#include <SDL3/SDL_rect.h>
+#include <SDL3/SDL_render.h>
+#include <SDL3/SDL_scancode.h>
+#include <SDL3/SDL_sensor.h>
+#include <SDL3/SDL_storage.h>
+#include <SDL3/SDL_surface.h>
+#include <SDL3/SDL_system.h>
+#include <SDL3/SDL_thread.h>
+#include <SDL3/SDL_time.h>
+#include <SDL3/SDL_timer.h>
+#include <SDL3/SDL_tray.h>
+#include <SDL3/SDL_touch.h>
+#include <SDL3/SDL_version.h>
+#include <SDL3/SDL_video.h>
+#include <SDL3/SDL_oldnames.h>
+
+#endif /* SDL_h_ */

Source/ThirdParty/SDL/SDL3/SDL_assert.h

@@ -0,0 +1,658 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2024 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+/**
+ * # CategoryAssert
+ *
+ * A helpful assertion macro!
+ *
+ * SDL assertions operate like your usual `assert` macro, but with some added
+ * features:
+ *
+ * - It uses a trick with the `sizeof` operator, so disabled assertions
+ *   vaporize out of the compiled code, but variables only referenced in the
+ *   assertion won't trigger compiler warnings about being unused.
+ * - It is safe to use with a dangling-else: `if (x) SDL_assert(y); else
+ *   do_something();`
+ * - It works the same everywhere, instead of counting on various platforms'
+ *   compiler and C runtime to behave.
+ * - It provides multiple levels of assertion (SDL_assert, SDL_assert_release,
+ *   SDL_assert_paranoid) instead of a single all-or-nothing option.
+ * - It offers a variety of responses when an assertion fails (retry, trigger
+ *   the debugger, abort the program, ignore the failure once, ignore it for
+ *   the rest of the program's run).
+ * - It tries to show the user a dialog by default, if possible, but the app
+ *   can provide a callback to handle assertion failures however they like.
+ * - It lets failed assertions be retried. Perhaps you had a network failure
+ *   and just want to retry the test after plugging your network cable back
+ *   in? You can.
+ * - It lets the user ignore an assertion failure, if there's a harmless
+ *   problem that one can continue past.
+ * - It lets the user mark an assertion as ignored for the rest of the
+ *   program's run; if there's a harmless problem that keeps popping up.
+ * - It provides statistics and data on all failed assertions to the app.
+ * - It allows the default assertion handler to be controlled with environment
+ *   variables, in case an automated script needs to control it.
+ * - It can be used as an aid to Clang's static analysis; it will treat SDL
+ *   assertions as universally true (under the assumption that you are serious
+ *   about the asserted claims and that your debug builds will detect when
+ *   these claims were wrong). This can help the analyzer avoid false
+ *   positives.
+ *
+ * To use it: compile a debug build and just sprinkle around tests to check
+ * your code!
+ */
+
+#ifndef SDL_assert_h_
+#define SDL_assert_h_
+
+#include <SDL3/SDL_stdinc.h>
+
+#include <SDL3/SDL_begin_code.h>
+/* Set up for C function definitions, even when using C++ */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef SDL_WIKI_DOCUMENTATION_SECTION
+
+/**
+ * The level of assertion aggressiveness.
+ *
+ * This value changes depending on compiler options and other preprocessor
+ * defines.
+ *
+ * It is currently one of the following values, but future SDL releases might
+ * add more:
+ *
+ * - 0: All SDL assertion macros are disabled.
+ * - 1: Release settings: SDL_assert disabled, SDL_assert_release enabled.
+ * - 2: Debug settings: SDL_assert and SDL_assert_release enabled.
+ * - 3: Paranoid settings: All SDL assertion macros enabled, including
+ *   SDL_assert_paranoid.
+ *
+ * \since This macro is available since SDL 3.1.3.
+ */
+#define SDL_ASSERT_LEVEL SomeNumberBasedOnVariousFactors
+
+#elif !defined(SDL_ASSERT_LEVEL)
+#ifdef SDL_DEFAULT_ASSERT_LEVEL
+#define SDL_ASSERT_LEVEL SDL_DEFAULT_ASSERT_LEVEL
+#elif defined(_DEBUG) || defined(DEBUG) || \
+      (defined(__GNUC__) && !defined(__OPTIMIZE__))
+#define SDL_ASSERT_LEVEL 2
+#else
+#define SDL_ASSERT_LEVEL 1
+#endif
+#endif
+
+#ifdef SDL_WIKI_DOCUMENTATION_SECTION
+
+/**
+ * Attempt to tell an attached debugger to pause.
+ *
+ * This allows an app to programmatically halt ("break") the debugger as if it
+ * had hit a breakpoint, allowing the developer to examine program state, etc.
+ *
+ * This is a macro--not a function--so that the debugger breaks on the source
+ * code line that used SDL_TriggerBreakpoint and not in some random guts of
+ * SDL. SDL_assert uses this macro for the same reason.
+ *
+ * If the program is not running under a debugger, SDL_TriggerBreakpoint will
+ * likely terminate the app, possibly without warning. If the current platform
+ * isn't supported (SDL doesn't know how to trigger a breakpoint), this macro
+ * does nothing.
+ *
+ * \threadsafety It is safe to call this macro from any thread.
+ *
+ * \since This macro is available since SDL 3.1.3.
+ */
+#define SDL_TriggerBreakpoint() TriggerABreakpointInAPlatformSpecificManner
+
+#elif defined(_MSC_VER)
+    /* Don't include intrin.h here because it contains C++ code */
+    extern void __cdecl __debugbreak(void);
+    #define SDL_TriggerBreakpoint() __debugbreak()
+#elif defined(ANDROID)
+    #include <assert.h>
+    #define SDL_TriggerBreakpoint() assert(0)
+#elif SDL_HAS_BUILTIN(__builtin_debugtrap)
+    #define SDL_TriggerBreakpoint() __builtin_debugtrap()
+#elif (defined(__GNUC__) || defined(__clang__)) && (defined(__i386__) || defined(__x86_64__))
+    #define SDL_TriggerBreakpoint() __asm__ __volatile__ ( "int $3\n\t" )
+#elif (defined(__GNUC__) || defined(__clang__)) && defined(__riscv)
+    #define SDL_TriggerBreakpoint() __asm__ __volatile__ ( "ebreak\n\t" )
+#elif ( defined(SDL_PLATFORM_APPLE) && (defined(__arm64__) || defined(__aarch64__)) )  /* this might work on other ARM targets, but this is a known quantity... */
+    #define SDL_TriggerBreakpoint() __asm__ __volatile__ ( "brk #22\n\t" )
+#elif defined(SDL_PLATFORM_APPLE) && defined(__arm__)
+    #define SDL_TriggerBreakpoint() __asm__ __volatile__ ( "bkpt #22\n\t" )
+#elif defined(_WIN32) && ((defined(__GNUC__) || defined(__clang__)) && (defined(__arm64__) || defined(__aarch64__)) )
+    #define SDL_TriggerBreakpoint() __asm__ __volatile__ ( "brk #0xF000\n\t" )
+#elif defined(__386__) && defined(__WATCOMC__)
+    #define SDL_TriggerBreakpoint() { _asm { int 0x03 } }
+#elif defined(HAVE_SIGNAL_H) && !defined(__WATCOMC__)
+    #include <signal.h>
+    #define SDL_TriggerBreakpoint() raise(SIGTRAP)
+#else
+    /* How do we trigger breakpoints on this platform? */
+    #define SDL_TriggerBreakpoint()
+#endif
+
+#ifdef SDL_WIKI_DOCUMENTATION_SECTION
+
+/**
+ * A macro that reports the current function being compiled.
+ *
+ * If SDL can't figure how the compiler reports this, it will use "???".
+ *
+ * \since This macro is available since SDL 3.1.3.
+ */
+#define SDL_FUNCTION __FUNCTION__
+
+#elif defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 supports __func__ as a standard. */
+#   define SDL_FUNCTION __func__
+#elif ((defined(__GNUC__) && (__GNUC__ >= 2)) || defined(_MSC_VER) || defined (__WATCOMC__))
+#   define SDL_FUNCTION __FUNCTION__
+#else
+#   define SDL_FUNCTION "???"
+#endif
+
+/**
+ * A macro that reports the current file being compiled.
+ *
+ * \since This macro is available since SDL 3.1.3.
+ */
+#define SDL_FILE    __FILE__
+
+/**
+ * A macro that reports the current line number of the file being compiled.
+ *
+ * \since This macro is available since SDL 3.1.3.
+ */
+#define SDL_LINE    __LINE__
+
+/*
+sizeof (x) makes the compiler still parse the expression even without
+assertions enabled, so the code is always checked at compile time, but
+doesn't actually generate code for it, so there are no side effects or
+expensive checks at run time, just the constant size of what x WOULD be,
+which presumably gets optimized out as unused.
+This also solves the problem of...
+
+    int somevalue = blah();
+    SDL_assert(somevalue == 1);
+
+...which would cause compiles to complain that somevalue is unused if we
+disable assertions.
+*/
+
+#ifdef SDL_WIKI_DOCUMENTATION_SECTION
+
+/**
+ * A macro for wrapping code in `do {} while (0);` without compiler warnings.
+ *
+ * Visual Studio with really aggressive warnings enabled needs this to avoid
+ * compiler complaints.
+ *
+ * the `do {} while (0);` trick is useful for wrapping code in a macro that
+ * may or may not be a single statement, to avoid various C language
+ * accidents.
+ *
+ * To use:
+ *
+ * ```c
+ * do { SomethingOnce(); } while (SDL_NULL_WHILE_LOOP_CONDITION (0));
+ * ```
+ *
+ * \since This macro is available since SDL 3.1.3.
+ */
+#define SDL_NULL_WHILE_LOOP_CONDITION (0)
+
+#elif defined(_MSC_VER)  /* Avoid /W4 warnings. */
+/* "while (0,0)" fools Microsoft's compiler's /W4 warning level into thinking
+    this condition isn't constant. And looks like an owl's face! */
+#define SDL_NULL_WHILE_LOOP_CONDITION (0,0)
+#else
+#define SDL_NULL_WHILE_LOOP_CONDITION (0)
+#endif
+
+/**
+ * The macro used when an assertion is disabled.
+ *
+ * This isn't for direct use by apps, but this is the code that is inserted
+ * when an SDL_assert is disabled (perhaps in a release build).
+ *
+ * The code does nothing, but wraps `condition` in a sizeof operator, which
+ * generates no code and has no side effects, but avoid compiler warnings
+ * about unused variables.
+ *
+ * \param condition the condition to assert (but not actually run here).
+ *
+ * \since This macro is available since SDL 3.1.3.
+ */
+#define SDL_disabled_assert(condition) \
+    do { (void) sizeof ((condition)); } while (SDL_NULL_WHILE_LOOP_CONDITION)
+
+/**
+ * Possible outcomes from a triggered assertion.
+ *
+ * When an enabled assertion triggers, it may call the assertion handler
+ * (possibly one provided by the app via SDL_SetAssertionHandler), which will
+ * return one of these values, possibly after asking the user.
+ *
+ * Then SDL will respond based on this outcome (loop around to retry the
+ * condition, try to break in a debugger, kill the program, or ignore the
+ * problem).
+ *
+ * \since This enum is available since SDL 3.1.3.
+ */
+typedef enum SDL_AssertState
+{
+    SDL_ASSERTION_RETRY,  /**< Retry the assert immediately. */
+    SDL_ASSERTION_BREAK,  /**< Make the debugger trigger a breakpoint. */
+    SDL_ASSERTION_ABORT,  /**< Terminate the program. */
+    SDL_ASSERTION_IGNORE,  /**< Ignore the assert. */
+    SDL_ASSERTION_ALWAYS_IGNORE  /**< Ignore the assert from now on. */
+} SDL_AssertState;
+
+/**
+ * Information about an assertion failure.
+ *
+ * This structure is filled in with information about a triggered assertion,
+ * used by the assertion handler, then added to the assertion report. This is
+ * returned as a linked list from SDL_GetAssertionReport().
+ *
+ * \since This struct is available since SDL 3.1.3.
+ */
+typedef struct SDL_AssertData
+{
+    bool always_ignore;  /**< true if app should always continue when assertion is triggered. */
+    unsigned int trigger_count; /**< Number of times this assertion has been triggered. */
+    const char *condition;  /**< A string of this assert's test code. */
+    const char *filename;  /**< The source file where this assert lives. */
+    int linenum;  /**< The line in `filename` where this assert lives. */
+    const char *function;  /**< The name of the function where this assert lives. */
+    const struct SDL_AssertData *next;  /**< next item in the linked list. */
+} SDL_AssertData;
+
+/**
+ * Never call this directly.
+ *
+ * Use the SDL_assert macros instead.
+ *
+ * \param data assert data structure.
+ * \param func function name.
+ * \param file file name.
+ * \param line line number.
+ * \returns assert state.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.1.3.
+ */
+extern SDL_DECLSPEC SDL_AssertState SDLCALL SDL_ReportAssertion(SDL_AssertData *data,
+                                                            const char *func,
+                                                            const char *file, int line) SDL_ANALYZER_NORETURN;
+
+
+#ifdef SDL_WIKI_DOCUMENTATION_SECTION
+
+/**
+ * The macro used when an assertion triggers a breakpoint.
+ *
+ * This isn't for direct use by apps; use SDL_assert or SDL_TriggerBreakpoint
+ * instead.
+ *
+ * \since This macro is available since SDL 3.1.3.
+ */
+#define SDL_AssertBreakpoint() SDL_TriggerBreakpoint()
+
+#elif !defined(SDL_AssertBreakpoint)
+#  if defined(ANDROID) && defined(assert)
+     /* Define this as empty in case assert() is defined as SDL_assert */
+#    define SDL_AssertBreakpoint()
+#  else
+#    define SDL_AssertBreakpoint() SDL_TriggerBreakpoint()
+#  endif
+#endif /* !SDL_AssertBreakpoint */
+
+/**
+ * The macro used when an assertion is enabled.
+ *
+ * This isn't for direct use by apps, but this is the code that is inserted
+ * when an SDL_assert is enabled.
+ *
+ * The `do {} while(0)` avoids dangling else problems:
+ *
+ * ```c
+ * if (x) SDL_assert(y); else blah();
+ * ```
+ *
+ * ... without the do/while, the "else" could attach to this macro's "if". We
+ * try to handle just the minimum we need here in a macro...the loop, the
+ * static vars, and break points. The heavy lifting is handled in
+ * SDL_ReportAssertion().
+ *
+ * \param condition the condition to assert.
+ *
+ * \since This macro is available since SDL 3.1.3.
+ */
+#define SDL_enabled_assert(condition) \
+    do { \
+        while ( !(condition) ) { \
+            static struct SDL_AssertData sdl_assert_data = { 0, 0, #condition, 0, 0, 0, 0 }; \
+            const SDL_AssertState sdl_assert_state = SDL_ReportAssertion(&sdl_assert_data, SDL_FUNCTION, SDL_FILE, SDL_LINE); \
+            if (sdl_assert_state == SDL_ASSERTION_RETRY) { \
+                continue; /* go again. */ \
+            } else if (sdl_assert_state == SDL_ASSERTION_BREAK) { \
+                SDL_AssertBreakpoint(); \
+            } \
+            break; /* not retrying. */ \
+        } \
+    } while (SDL_NULL_WHILE_LOOP_CONDITION)
+
+#ifdef SDL_WIKI_DOCUMENTATION_SECTION
+
+/**
+ * An assertion test that is normally performed only in debug builds.
+ *
+ * This macro is enabled when the SDL_ASSERT_LEVEL is >= 2, otherwise it is
+ * disabled. This is meant to only do these tests in debug builds, so they can
+ * tend to be more expensive, and they are meant to bring everything to a halt
+ * when they fail, with the programmer there to assess the problem.
+ *
+ * In short: you can sprinkle these around liberally and assume they will
+ * evaporate out of the build when building for end-users.
+ *
+ * When assertions are disabled, this wraps `condition` in a `sizeof`
+ * operator, which means any function calls and side effects will not run, but
+ * the compiler will not complain about any otherwise-unused variables that
+ * are only referenced in the assertion.
+ *
+ * One can set the environment variable "SDL_ASSERT" to one of several strings
+ * ("abort", "break", "retry", "ignore", "always_ignore") to force a default
+ * behavior, which may be desirable for automation purposes. If your platform
+ * requires GUI interfaces to happen on the main thread but you're debugging
+ * an assertion in a background thread, it might be desirable to set this to
+ * "break" so that your debugger takes control as soon as assert is triggered,
+ * instead of risking a bad UI interaction (deadlock, etc) in the application.
+ *
+ * \param condition boolean value to test.
+ *
+ * \threadsafety It is safe to call this macro from any thread.
+ *
+ * \since This macro is available since SDL 3.1.3.
+ */
+#define SDL_assert(condition) if (assertion_enabled && (condition)) { trigger_assertion; }
+
+/**
+ * An assertion test that is performed even in release builds.
+ *
+ * This macro is enabled when the SDL_ASSERT_LEVEL is >= 1, otherwise it is
+ * disabled. This is meant to be for tests that are cheap to make and
+ * extremely unlikely to fail; generally it is frowned upon to have an
+ * assertion failure in a release build, so these assertions generally need to
+ * be of more than life-and-death importance if there's a chance they might
+ * trigger. You should almost always consider handling these cases more
+ * gracefully than an assert allows.
+ *
+ * When assertions are disabled, this wraps `condition` in a `sizeof`
+ * operator, which means any function calls and side effects will not run, but
+ * the compiler will not complain about any otherwise-unused variables that
+ * are only referenced in the assertion.
+ *
+ * One can set the environment variable "SDL_ASSERT" to one of several strings
+ * ("abort", "break", "retry", "ignore", "always_ignore") to force a default
+ * behavior, which may be desirable for automation purposes. If your platform
+ * requires GUI interfaces to happen on the main thread but you're debugging
+ * an assertion in a background thread, it might be desirable to set this to
+ * "break" so that your debugger takes control as soon as assert is triggered,
+ * instead of risking a bad UI interaction (deadlock, etc) in the application.
+ * *
+ *
+ * \param condition boolean value to test.
+ *
+ * \threadsafety It is safe to call this macro from any thread.
+ *
+ * \since This macro is available since SDL 3.1.3.
+ */
+#define SDL_assert_release(condition) SDL_disabled_assert(condition)
+
+/**
+ * An assertion test that is performed only when built with paranoid settings.
+ *
+ * This macro is enabled when the SDL_ASSERT_LEVEL is >= 3, otherwise it is
+ * disabled. This is a higher level than both release and debug, so these
+ * tests are meant to be expensive and only run when specifically looking for
+ * extremely unexpected failure cases in a special build.
+ *
+ * When assertions are disabled, this wraps `condition` in a `sizeof`
+ * operator, which means any function calls and side effects will not run, but
+ * the compiler will not complain about any otherwise-unused variables that
+ * are only referenced in the assertion.
+ *
+ * One can set the environment variable "SDL_ASSERT" to one of several strings
+ * ("abort", "break", "retry", "ignore", "always_ignore") to force a default
+ * behavior, which may be desirable for automation purposes. If your platform
+ * requires GUI interfaces to happen on the main thread but you're debugging
+ * an assertion in a background thread, it might be desirable to set this to
+ * "break" so that your debugger takes control as soon as assert is triggered,
+ * instead of risking a bad UI interaction (deadlock, etc) in the application.
+ *
+ * \param condition boolean value to test.
+ *
+ * \threadsafety It is safe to call this macro from any thread.
+ *
+ * \since This macro is available since SDL 3.1.3.
+ */
+#define SDL_assert_paranoid(condition) SDL_disabled_assert(condition)
+
+/* Enable various levels of assertions. */
+#elif SDL_ASSERT_LEVEL == 0   /* assertions disabled */
+#   define SDL_assert(condition) SDL_disabled_assert(condition)
+#   define SDL_assert_release(condition) SDL_disabled_assert(condition)
+#   define SDL_assert_paranoid(condition) SDL_disabled_assert(condition)
+#elif SDL_ASSERT_LEVEL == 1  /* release settings. */
+#   define SDL_assert(condition) SDL_disabled_assert(condition)
+#   define SDL_assert_release(condition) SDL_enabled_assert(condition)
+#   define SDL_assert_paranoid(condition) SDL_disabled_assert(condition)
+#elif SDL_ASSERT_LEVEL == 2  /* debug settings. */
+#   define SDL_assert(condition) SDL_enabled_assert(condition)
+#   define SDL_assert_release(condition) SDL_enabled_assert(condition)
+#   define SDL_assert_paranoid(condition) SDL_disabled_assert(condition)
+#elif SDL_ASSERT_LEVEL == 3  /* paranoid settings. */
+#   define SDL_assert(condition) SDL_enabled_assert(condition)
+#   define SDL_assert_release(condition) SDL_enabled_assert(condition)
+#   define SDL_assert_paranoid(condition) SDL_enabled_assert(condition)
+#else
+#   error Unknown assertion level.
+#endif
+
+/**
+ * An assertion test that is always performed.
+ *
+ * This macro is always enabled no matter what SDL_ASSERT_LEVEL is set to. You
+ * almost never want to use this, as it could trigger on an end-user's system,
+ * crashing your program.
+ *
+ * One can set the environment variable "SDL_ASSERT" to one of several strings
+ * ("abort", "break", "retry", "ignore", "always_ignore") to force a default
+ * behavior, which may be desirable for automation purposes. If your platform
+ * requires GUI interfaces to happen on the main thread but you're debugging
+ * an assertion in a background thread, it might be desirable to set this to
+ * "break" so that your debugger takes control as soon as assert is triggered,
+ * instead of risking a bad UI interaction (deadlock, etc) in the application.
+ *
+ * \param condition boolean value to test.
+ *
+ * \threadsafety It is safe to call this macro from any thread.
+ *
+ * \since This macro is available since SDL 3.1.3.
+ */
+#define SDL_assert_always(condition) SDL_enabled_assert(condition)
+
+
+/**
+ * A callback that fires when an SDL assertion fails.
+ *
+ * \param data a pointer to the SDL_AssertData structure corresponding to the
+ *             current assertion.
+ * \param userdata what was passed as `userdata` to SDL_SetAssertionHandler().
+ * \returns an SDL_AssertState value indicating how to handle the failure.
+ *
+ * \threadsafety This callback may be called from any thread that triggers an
+ *               assert at any time.
+ *
+ * \since This datatype is available since SDL 3.1.3.
+ */
+typedef SDL_AssertState (SDLCALL *SDL_AssertionHandler)(
+                                 const SDL_AssertData *data, void *userdata);
+
+/**
+ * Set an application-defined assertion handler.
+ *
+ * This function allows an application to show its own assertion UI and/or
+ * force the response to an assertion failure. If the application doesn't
+ * provide this, SDL will try to do the right thing, popping up a
+ * system-specific GUI dialog, and probably minimizing any fullscreen windows.
+ *
+ * This callback may fire from any thread, but it runs wrapped in a mutex, so
+ * it will only fire from one thread at a time.
+ *
+ * This callback is NOT reset to SDL's internal handler upon SDL_Quit()!
+ *
+ * \param handler the SDL_AssertionHandler function to call when an assertion
+ *                fails or NULL for the default handler.
+ * \param userdata a pointer that is passed to `handler`.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_GetAssertionHandler
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_SetAssertionHandler(
+                                            SDL_AssertionHandler handler,
+                                            void *userdata);
+
+/**
+ * Get the default assertion handler.
+ *
+ * This returns the function pointer that is called by default when an
+ * assertion is triggered. This is an internal function provided by SDL, that
+ * is used for assertions when SDL_SetAssertionHandler() hasn't been used to
+ * provide a different function.
+ *
+ * \returns the default SDL_AssertionHandler that is called when an assert
+ *          triggers.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_GetAssertionHandler
+ */
+extern SDL_DECLSPEC SDL_AssertionHandler SDLCALL SDL_GetDefaultAssertionHandler(void);
+
+/**
+ * Get the current assertion handler.
+ *
+ * This returns the function pointer that is called when an assertion is
+ * triggered. This is either the value last passed to
+ * SDL_SetAssertionHandler(), or if no application-specified function is set,
+ * is equivalent to calling SDL_GetDefaultAssertionHandler().
+ *
+ * The parameter `puserdata` is a pointer to a void*, which will store the
+ * "userdata" pointer that was passed to SDL_SetAssertionHandler(). This value
+ * will always be NULL for the default handler. If you don't care about this
+ * data, it is safe to pass a NULL pointer to this function to ignore it.
+ *
+ * \param puserdata pointer which is filled with the "userdata" pointer that
+ *                  was passed to SDL_SetAssertionHandler().
+ * \returns the SDL_AssertionHandler that is called when an assert triggers.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_SetAssertionHandler
+ */
+extern SDL_DECLSPEC SDL_AssertionHandler SDLCALL SDL_GetAssertionHandler(void **puserdata);
+
+/**
+ * Get a list of all assertion failures.
+ *
+ * This function gets all assertions triggered since the last call to
+ * SDL_ResetAssertionReport(), or the start of the program.
+ *
+ * The proper way to examine this data looks something like this:
+ *
+ * ```c
+ * const SDL_AssertData *item = SDL_GetAssertionReport();
+ * while (item) {
+ *    printf("'%s', %s (%s:%d), triggered %u times, always ignore: %s.\\n",
+ *           item->condition, item->function, item->filename,
+ *           item->linenum, item->trigger_count,
+ *           item->always_ignore ? "yes" : "no");
+ *    item = item->next;
+ * }
+ * ```
+ *
+ * \returns a list of all failed assertions or NULL if the list is empty. This
+ *          memory should not be modified or freed by the application. This
+ *          pointer remains valid until the next call to SDL_Quit() or
+ *          SDL_ResetAssertionReport().
+ *
+ * \threadsafety This function is not thread safe. Other threads calling
+ *               SDL_ResetAssertionReport() simultaneously, may render the
+ *               returned pointer invalid.
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_ResetAssertionReport
+ */
+extern SDL_DECLSPEC const SDL_AssertData * SDLCALL SDL_GetAssertionReport(void);
+
+/**
+ * Clear the list of all assertion failures.
+ *
+ * This function will clear the list of all assertions triggered up to that
+ * point. Immediately following this call, SDL_GetAssertionReport will return
+ * no items. In addition, any previously-triggered assertions will be reset to
+ * a trigger_count of zero, and their always_ignore state will be false.
+ *
+ * \threadsafety This function is not thread safe. Other threads triggering an
+ *               assertion, or simultaneously calling this function may cause
+ *               memory leaks or crashes.
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_GetAssertionReport
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_ResetAssertionReport(void);
+
+/* Ends C function definitions when using C++ */
+#ifdef __cplusplus
+}
+#endif
+#include <SDL3/SDL_close_code.h>
+
+#endif /* SDL_assert_h_ */

Source/ThirdParty/SDL/SDL3/SDL_asyncio.h

@@ -0,0 +1,546 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2024 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+/* WIKI CATEGORY: AsyncIO */
+
+/**
+ * # CategoryAsyncIO
+ *
+ * SDL offers a way to perform I/O asynchronously. This allows an app to read
+ * or write files without waiting for data to actually transfer; the functions
+ * that request I/O never block while the request is fulfilled.
+ *
+ * Instead, the data moves in the background and the app can check for results
+ * at their leisure.
+ *
+ * This is more complicated than just reading and writing files in a
+ * synchronous way, but it can allow for more efficiency, and never having
+ * framerate drops as the hard drive catches up, etc.
+ *
+ * The general usage pattern for async I/O is:
+ *
+ * - Create one or more SDL_AsyncIOQueue objects.
+ * - Open files with SDL_AsyncIOFromFile.
+ * - Start I/O tasks to the files with SDL_ReadAsyncIO or SDL_WriteAsyncIO,
+ *   putting those tasks into one of the queues.
+ * - Later on, use SDL_GetAsyncIOResult on a queue to see if any task is
+ *   finished without blocking. Tasks might finish in any order with success
+ *   or failure.
+ * - When all your tasks are done, close the file with SDL_CloseAsyncIO. This
+ *   also generates a task, since it might flush data to disk!
+ *
+ * This all works, without blocking, in a single thread, but one can also wait
+ * on a queue in a background thread, sleeping until new results have arrived:
+ *
+ * - Call SDL_WaitAsyncIOResult from one or more threads to efficiently block
+ *   until new tasks complete.
+ * - When shutting down, call SDL_SignalAsyncIOQueue to unblock any sleeping
+ *   threads despite there being no new tasks completed.
+ *
+ * And, of course, to match the synchronous SDL_LoadFile, we offer
+ * SDL_LoadFileAsync as a convenience function. This will handle allocating a
+ * buffer, slurping in the file data, and null-terminating it; you still check
+ * for results later.
+ *
+ * Behind the scenes, SDL will use newer, efficient APIs on platforms that
+ * support them: Linux's io_uring and Windows 11's IoRing, for example. If
+ * those technologies aren't available, SDL will offload the work to a thread
+ * pool that will manage otherwise-synchronous loads without blocking the app.
+ *
+ * ## Best Practices
+ *
+ * Simple non-blocking i/o--for an app that just wants to pick up data
+ * whenever it's ready without losing framerate waiting on disks to spin--can
+ * use whatever pattern works well for the program. In this case, simply call
+ * SDL_ReadAsyncIO, or maybe SDL_LoadFileAsync, as needed. Once a frame, call
+ * SDL_GetAsyncIOResult to check for any completed tasks and deal with the
+ * data as it arrives.
+ *
+ * If two separate pieces of the same program need their own i/o, it is legal
+ * for each to create their own queue. This will prevent either piece from
+ * accidentally consuming the other's completed tasks. Each queue does require
+ * some amount of resources, but it is not an overwhelming cost. Do not make a
+ * queue for each task, however. It is better to put many tasks into a single
+ * queue. They will be reported in order of completion, not in the order they
+ * were submitted, so it doesn't generally matter what order tasks are
+ * started.
+ *
+ * One async i/o queue can be shared by multiple threads, or one thread can
+ * have more than one queue, but the most efficient way--if ruthless
+ * efficiency is the goal--is to have one queue per thread, with multiple
+ * threads working in parallel, and attempt to keep each queue loaded with
+ * tasks that are both started by and consumed by the same thread. On modern
+ * platforms that can use newer interfaces, this can keep data flowing as
+ * efficiently as possible all the way from storage hardware to the app, with
+ * no contention between threads for access to the same queue.
+ *
+ * Written data is not guaranteed to make it to physical media by the time a
+ * closing task is completed, unless SDL_CloseAsyncIO is called with its
+ * `flush` parameter set to true, which is to say that a successful result
+ * here can still result in lost data during an unfortunately-timed power
+ * outage if not flushed. However, flushing will take longer and may be
+ * unnecessary, depending on the app's needs.
+ */
+
+#ifndef SDL_asyncio_h_
+#define SDL_asyncio_h_
+
+#include <SDL3/SDL_stdinc.h>
+
+#include <SDL3/SDL_begin_code.h>
+/* Set up for C function definitions, even when using C++ */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * The asynchronous I/O operation structure.
+ *
+ * This operates as an opaque handle. One can then request read or write
+ * operations on it.
+ *
+ * \since This struct is available since SDL 3.0.0.
+ *
+ * \sa SDL_AsyncIOFromFile
+ */
+typedef struct SDL_AsyncIO SDL_AsyncIO;
+
+/**
+ * Types of asynchronous I/O tasks.
+ *
+ * \since This enum is available since SDL 3.0.0.
+ */
+typedef enum SDL_AsyncIOTaskType
+{
+    SDL_ASYNCIO_TASK_READ,   /**< A read operation. */
+    SDL_ASYNCIO_TASK_WRITE,  /**< A write operation. */
+    SDL_ASYNCIO_TASK_CLOSE   /**< A close operation. */
+} SDL_AsyncIOTaskType;
+
+/**
+ * Possible outcomes of an asynchronous I/O task.
+ *
+ * \since This enum is available since SDL 3.0.0.
+ */
+typedef enum SDL_AsyncIOResult
+{
+    SDL_ASYNCIO_COMPLETE,  /**< request was completed without error */
+    SDL_ASYNCIO_FAILURE,   /**< request failed for some reason; check SDL_GetError()! */
+    SDL_ASYNCIO_CANCELED   /**< request was canceled before completing. */
+} SDL_AsyncIOResult;
+
+/**
+ * Information about a completed asynchronous I/O request.
+ *
+ * \since This struct is available since SDL 3.0.0.
+ */
+typedef struct SDL_AsyncIOOutcome
+{
+    SDL_AsyncIO *asyncio;   /**< what generated this task. This pointer will be invalid if it was closed! */
+    SDL_AsyncIOTaskType type;  /**< What sort of task was this? Read, write, etc? */
+    SDL_AsyncIOResult result;  /**< the result of the work (success, failure, cancellation). */
+    void *buffer;  /**< buffer where data was read/written. */
+    Uint64 offset;  /**< offset in the SDL_AsyncIO where data was read/written. */
+    Uint64 bytes_requested;  /**< number of bytes the task was to read/write. */
+    Uint64 bytes_transferred;  /**< actual number of bytes that were read/written. */
+    void *userdata;    /**< pointer provided by the app when starting the task */
+} SDL_AsyncIOOutcome;
+
+/**
+ * A queue of completed asynchronous I/O tasks.
+ *
+ * When starting an asynchronous operation, you specify a queue for the new
+ * task. A queue can be asked later if any tasks in it have completed,
+ * allowing an app to manage multiple pending tasks in one place, in whatever
+ * order they complete.
+ *
+ * \since This struct is available since SDL 3.0.0.
+ *
+ * \sa SDL_CreateAsyncIOQueue
+ * \sa SDL_ReadAsyncIO
+ * \sa SDL_WriteAsyncIO
+ * \sa SDL_GetAsyncIOResult
+ * \sa SDL_WaitAsyncIOResult
+ */
+typedef struct SDL_AsyncIOQueue SDL_AsyncIOQueue;
+
+/**
+ * Use this function to create a new SDL_AsyncIO object for reading from
+ * and/or writing to a named file.
+ *
+ * The `mode` string understands the following values:
+ *
+ * - "r": Open a file for reading only. It must exist.
+ * - "w": Open a file for writing only. It will create missing files or
+ *   truncate existing ones.
+ * - "r+": Open a file for update both reading and writing. The file must
+ *   exist.
+ * - "w+": Create an empty file for both reading and writing. If a file with
+ *   the same name already exists its content is erased and the file is
+ *   treated as a new empty file.
+ *
+ * There is no "b" mode, as there is only "binary" style I/O, and no "a" mode
+ * for appending, since you specify the position when starting a task.
+ *
+ * This function supports Unicode filenames, but they must be encoded in UTF-8
+ * format, regardless of the underlying operating system.
+ *
+ * This call is _not_ asynchronous; it will open the file before returning,
+ * under the assumption that doing so is generally a fast operation. Future
+ * reads and writes to the opened file will be async, however.
+ *
+ * \param file a UTF-8 string representing the filename to open.
+ * \param mode an ASCII string representing the mode to be used for opening
+ *             the file.
+ * \returns a pointer to the SDL_AsyncIO structure that is created or NULL on
+ *          failure; call SDL_GetError() for more information.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_CloseAsyncIO
+ * \sa SDL_ReadAsyncIO
+ * \sa SDL_WriteAsyncIO
+ */
+extern SDL_DECLSPEC SDL_AsyncIO * SDLCALL SDL_AsyncIOFromFile(const char *file, const char *mode);
+
+/**
+ * Use this function to get the size of the data stream in an SDL_AsyncIO.
+ *
+ * This call is _not_ asynchronous; it assumes that obtaining this info is a
+ * non-blocking operation in most reasonable cases.
+ *
+ * \param asyncio the SDL_AsyncIO to get the size of the data stream from.
+ * \returns the size of the data stream in the SDL_IOStream on success or a
+ *          negative error code on failure; call SDL_GetError() for more
+ *          information.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.2.0.
+ */
+extern SDL_DECLSPEC Sint64 SDLCALL SDL_GetAsyncIOSize(SDL_AsyncIO *asyncio);
+
+/**
+ * Start an async read.
+ *
+ * This function reads up to `size` bytes from `offset` position in the data
+ * source to the area pointed at by `ptr`. This function may read less bytes
+ * than requested.
+ *
+ * This function returns as quickly as possible; it does not wait for the read
+ * to complete. On a successful return, this work will continue in the
+ * background. If the work begins, even failure is asynchronous: a failing
+ * return value from this function only means the work couldn't start at all.
+ *
+ * `ptr` must remain available until the work is done, and may be accessed by
+ * the system at any time until then. Do not allocate it on the stack, as this
+ * might take longer than the life of the calling function to complete!
+ *
+ * An SDL_AsyncIOQueue must be specified. The newly-created task will be added
+ * to it when it completes its work.
+ *
+ * \param asyncio a pointer to an SDL_AsyncIO structure.
+ * \param ptr a pointer to a buffer to read data into.
+ * \param offset the position to start reading in the data source.
+ * \param size the number of bytes to read from the data source.
+ * \param queue a queue to add the new SDL_AsyncIO to.
+ * \param userdata an app-defined pointer that will be provided with the task
+ *                 results.
+ * \returns true on success or false on failure; call SDL_GetError() for more
+ *          information.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_WriteAsyncIO
+ * \sa SDL_CreateAsyncIOQueue
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_ReadAsyncIO(SDL_AsyncIO *asyncio, void *ptr, Uint64 offset, Uint64 size, SDL_AsyncIOQueue *queue, void *userdata);
+
+/**
+ * Start an async write.
+ *
+ * This function writes `size` bytes from `offset` position in the data source
+ * to the area pointed at by `ptr`.
+ *
+ * This function returns as quickly as possible; it does not wait for the
+ * write to complete. On a successful return, this work will continue in the
+ * background. If the work begins, even failure is asynchronous: a failing
+ * return value from this function only means the work couldn't start at all.
+ *
+ * `ptr` must remain available until the work is done, and may be accessed by
+ * the system at any time until then. Do not allocate it on the stack, as this
+ * might take longer than the life of the calling function to complete!
+ *
+ * An SDL_AsyncIOQueue must be specified. The newly-created task will be added
+ * to it when it completes its work.
+ *
+ * \param asyncio a pointer to an SDL_AsyncIO structure.
+ * \param ptr a pointer to a buffer to write data from.
+ * \param offset the position to start writing to the data source.
+ * \param size the number of bytes to write to the data source.
+ * \param queue a queue to add the new SDL_AsyncIO to.
+ * \param userdata an app-defined pointer that will be provided with the task
+ *                 results.
+ * \returns true on success or false on failure; call SDL_GetError() for more
+ *          information.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_ReadAsyncIO
+ * \sa SDL_CreateAsyncIOQueue
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_WriteAsyncIO(SDL_AsyncIO *asyncio, void *ptr, Uint64 offset, Uint64 size, SDL_AsyncIOQueue *queue, void *userdata);
+
+/**
+ * Close and free any allocated resources for an async I/O object.
+ *
+ * Closing a file is _also_ an asynchronous task! If a write failure were to
+ * happen during the closing process, for example, the task results will
+ * report it as usual.
+ *
+ * Closing a file that has been written to does not guarantee the data has
+ * made it to physical media; it may remain in the operating system's file
+ * cache, for later writing to disk. This means that a successfully-closed
+ * file can be lost if the system crashes or loses power in this small window.
+ * To prevent this, call this function with the `flush` parameter set to true.
+ * This will make the operation take longer, and perhaps increase system load
+ * in general, but a successful result guarantees that the data has made it to
+ * physical storage. Don't use this for temporary files, caches, and
+ * unimportant data, and definitely use it for crucial irreplaceable files,
+ * like game saves.
+ *
+ * This function guarantees that the close will happen after any other pending
+ * tasks to `asyncio`, so it's safe to open a file, start several operations,
+ * close the file immediately, then check for all results later. This function
+ * will not block until the tasks have completed.
+ *
+ * Once this function returns true, `asyncio` is no longer valid, regardless
+ * of any future outcomes. Any completed tasks might still contain this
+ * pointer in their SDL_AsyncIOOutcome data, in case the app was using this
+ * value to track information, but it should not be used again.
+ *
+ * If this function returns false, the close wasn't started at all, and it's
+ * safe to attempt to close again later.
+ *
+ * An SDL_AsyncIOQueue must be specified. The newly-created task will be added
+ * to it when it completes its work.
+ *
+ * \param asyncio a pointer to an SDL_AsyncIO structure to close.
+ * \param flush true if data should sync to disk before the task completes.
+ * \param queue a queue to add the new SDL_AsyncIO to.
+ * \param userdata an app-defined pointer that will be provided with the task
+ *                 results.
+ * \returns true on success or false on failure; call SDL_GetError() for more
+ *          information.
+ *
+ * \threadsafety It is safe to call this function from any thread, but two
+ *               threads should not attempt to close the same object.
+ *
+ * \since This function is available since SDL 3.2.0.
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_CloseAsyncIO(SDL_AsyncIO *asyncio, bool flush, SDL_AsyncIOQueue *queue, void *userdata);
+
+/**
+ * Create a task queue for tracking multiple I/O operations.
+ *
+ * Async I/O operations are assigned to a queue when started. The queue can be
+ * checked for completed tasks thereafter.
+ *
+ * \returns a new task queue object or NULL if there was an error; call
+ *          SDL_GetError() for more information.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_DestroyAsyncIOQueue
+ * \sa SDL_GetAsyncIOResult
+ * \sa SDL_WaitAsyncIOResult
+ */
+extern SDL_DECLSPEC SDL_AsyncIOQueue * SDLCALL SDL_CreateAsyncIOQueue(void);
+
+/**
+ * Destroy a previously-created async I/O task queue.
+ *
+ * If there are still tasks pending for this queue, this call will block until
+ * those tasks are finished. All those tasks will be deallocated. Their
+ * results will be lost to the app.
+ *
+ * Any pending reads from SDL_LoadFileAsync() that are still in this queue
+ * will have their buffers deallocated by this function, to prevent a memory
+ * leak.
+ *
+ * Once this function is called, the queue is no longer valid and should not
+ * be used, including by other threads that might access it while destruction
+ * is blocking on pending tasks.
+ *
+ * Do not destroy a queue that still has threads waiting on it through
+ * SDL_WaitAsyncIOResult(). You can call SDL_SignalAsyncIOQueue() first to
+ * unblock those threads, and take measures (such as SDL_WaitThread()) to make
+ * sure they have finished their wait and won't wait on the queue again.
+ *
+ * \param queue the task queue to destroy.
+ *
+ * \threadsafety It is safe to call this function from any thread, so long as
+ *               no other thread is waiting on the queue with
+ *               SDL_WaitAsyncIOResult.
+ *
+ * \since This function is available since SDL 3.2.0.
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_DestroyAsyncIOQueue(SDL_AsyncIOQueue *queue);
+
+/**
+ * Query an async I/O task queue for completed tasks.
+ *
+ * If a task assigned to this queue has finished, this will return true and
+ * fill in `outcome` with the details of the task. If no task in the queue has
+ * finished, this function will return false. This function does not block.
+ *
+ * If a task has completed, this function will free its resources and the task
+ * pointer will no longer be valid. The task will be removed from the queue.
+ *
+ * It is safe for multiple threads to call this function on the same queue at
+ * once; a completed task will only go to one of the threads.
+ *
+ * \param queue the async I/O task queue to query.
+ * \param outcome details of a finished task will be written here. May not be
+ *                NULL.
+ * \returns true if a task has completed, false otherwise.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_WaitAsyncIOResult
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_GetAsyncIOResult(SDL_AsyncIOQueue *queue, SDL_AsyncIOOutcome *outcome);
+
+/**
+ * Block until an async I/O task queue has a completed task.
+ *
+ * This function puts the calling thread to sleep until there a task assigned
+ * to the queue that has finished.
+ *
+ * If a task assigned to the queue has finished, this will return true and
+ * fill in `outcome` with the details of the task. If no task in the queue has
+ * finished, this function will return false.
+ *
+ * If a task has completed, this function will free its resources and the task
+ * pointer will no longer be valid. The task will be removed from the queue.
+ *
+ * It is safe for multiple threads to call this function on the same queue at
+ * once; a completed task will only go to one of the threads.
+ *
+ * Note that by the nature of various platforms, more than one waiting thread
+ * may wake to handle a single task, but only one will obtain it, so
+ * `timeoutMS` is a _maximum_ wait time, and this function may return false
+ * sooner.
+ *
+ * This function may return false if there was a system error, the OS
+ * inadvertently awoke multiple threads, or if SDL_SignalAsyncIOQueue() was
+ * called to wake up all waiting threads without a finished task.
+ *
+ * A timeout can be used to specify a maximum wait time, but rather than
+ * polling, it is possible to have a timeout of -1 to wait forever, and use
+ * SDL_SignalAsyncIOQueue() to wake up the waiting threads later.
+ *
+ * \param queue the async I/O task queue to wait on.
+ * \param outcome details of a finished task will be written here. May not be
+ *                NULL.
+ * \param timeoutMS the maximum time to wait, in milliseconds, or -1 to wait
+ *                  indefinitely.
+ * \returns true if task has completed, false otherwise.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_SignalAsyncIOQueue
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_WaitAsyncIOResult(SDL_AsyncIOQueue *queue, SDL_AsyncIOOutcome *outcome, Sint32 timeoutMS);
+
+/**
+ * Wake up any threads that are blocking in SDL_WaitAsyncIOResult().
+ *
+ * This will unblock any threads that are sleeping in a call to
+ * SDL_WaitAsyncIOResult for the specified queue, and cause them to return
+ * from that function.
+ *
+ * This can be useful when destroying a queue to make sure nothing is touching
+ * it indefinitely. In this case, once this call completes, the caller should
+ * take measures to make sure any previously-blocked threads have returned
+ * from their wait and will not touch the queue again (perhaps by setting a
+ * flag to tell the threads to terminate and then using SDL_WaitThread() to
+ * make sure they've done so).
+ *
+ * \param queue the async I/O task queue to signal.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_WaitAsyncIOResult
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_SignalAsyncIOQueue(SDL_AsyncIOQueue *queue);
+
+/**
+ * Load all the data from a file path, asynchronously.
+ *
+ * This function returns as quickly as possible; it does not wait for the read
+ * to complete. On a successful return, this work will continue in the
+ * background. If the work begins, even failure is asynchronous: a failing
+ * return value from this function only means the work couldn't start at all.
+ *
+ * The data is allocated with a zero byte at the end (null terminated) for
+ * convenience. This extra byte is not included in SDL_AsyncIOOutcome's
+ * bytes_transferred value.
+ *
+ * This function will allocate the buffer to contain the file. It must be
+ * deallocated by calling SDL_free() on SDL_AsyncIOOutcome's buffer field
+ * after completion.
+ *
+ * An SDL_AsyncIOQueue must be specified. The newly-created task will be added
+ * to it when it completes its work.
+ *
+ * \param file the path to read all available data from.
+ * \param queue a queue to add the new SDL_AsyncIO to.
+ * \param userdata an app-defined pointer that will be provided with the task
+ *                 results.
+ * \returns true on success or false on failure; call SDL_GetError() for more
+ *          information.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_LoadFile_IO
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_LoadFileAsync(const char *file, SDL_AsyncIOQueue *queue, void *userdata);
+
+/* Ends C function definitions when using C++ */
+#ifdef __cplusplus
+}
+#endif
+#include <SDL3/SDL_close_code.h>
+
+#endif /* SDL_asyncio_h_ */

Source/ThirdParty/SDL/SDL3/SDL_atomic.h

@@ -0,0 +1,664 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2024 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+/**
+ * # CategoryAtomic
+ *
+ * Atomic operations.
+ *
+ * IMPORTANT: If you are not an expert in concurrent lockless programming, you
+ * should not be using any functions in this file. You should be protecting
+ * your data structures with full mutexes instead.
+ *
+ * ***Seriously, here be dragons!***
+ *
+ * You can find out a little more about lockless programming and the subtle
+ * issues that can arise here:
+ * https://learn.microsoft.com/en-us/windows/win32/dxtecharts/lockless-programming
+ *
+ * There's also lots of good information here:
+ *
+ * - https://www.1024cores.net/home/lock-free-algorithms
+ * - https://preshing.com/
+ *
+ * These operations may or may not actually be implemented using processor
+ * specific atomic operations. When possible they are implemented as true
+ * processor specific atomic operations. When that is not possible the are
+ * implemented using locks that *do* use the available atomic operations.
+ *
+ * All of the atomic operations that modify memory are full memory barriers.
+ */
+
+#ifndef SDL_atomic_h_
+#define SDL_atomic_h_
+
+#include <SDL3/SDL_stdinc.h>
+#include <SDL3/SDL_platform_defines.h>
+
+#include <SDL3/SDL_begin_code.h>
+
+/* Set up for C function definitions, even when using C++ */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * An atomic spinlock.
+ *
+ * The atomic locks are efficient spinlocks using CPU instructions, but are
+ * vulnerable to starvation and can spin forever if a thread holding a lock
+ * has been terminated. For this reason you should minimize the code executed
+ * inside an atomic lock and never do expensive things like API or system
+ * calls while holding them.
+ *
+ * They are also vulnerable to starvation if the thread holding the lock is
+ * lower priority than other threads and doesn't get scheduled. In general you
+ * should use mutexes instead, since they have better performance and
+ * contention behavior.
+ *
+ * The atomic locks are not safe to lock recursively.
+ *
+ * Porting Note: The spin lock functions and type are required and can not be
+ * emulated because they are used in the atomic emulation code.
+ */
+typedef int SDL_SpinLock;
+
+/**
+ * Try to lock a spin lock by setting it to a non-zero value.
+ *
+ * ***Please note that spinlocks are dangerous if you don't know what you're
+ * doing. Please be careful using any sort of spinlock!***
+ *
+ * \param lock a pointer to a lock variable.
+ * \returns true if the lock succeeded, false if the lock is already held.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_LockSpinlock
+ * \sa SDL_UnlockSpinlock
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_TryLockSpinlock(SDL_SpinLock *lock);
+
+/**
+ * Lock a spin lock by setting it to a non-zero value.
+ *
+ * ***Please note that spinlocks are dangerous if you don't know what you're
+ * doing. Please be careful using any sort of spinlock!***
+ *
+ * \param lock a pointer to a lock variable.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_TryLockSpinlock
+ * \sa SDL_UnlockSpinlock
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_LockSpinlock(SDL_SpinLock *lock);
+
+/**
+ * Unlock a spin lock by setting it to 0.
+ *
+ * Always returns immediately.
+ *
+ * ***Please note that spinlocks are dangerous if you don't know what you're
+ * doing. Please be careful using any sort of spinlock!***
+ *
+ * \param lock a pointer to a lock variable.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_LockSpinlock
+ * \sa SDL_TryLockSpinlock
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_UnlockSpinlock(SDL_SpinLock *lock);
+
+
+#ifdef SDL_WIKI_DOCUMENTATION_SECTION
+
+/**
+ * Mark a compiler barrier.
+ *
+ * A compiler barrier prevents the compiler from reordering reads and writes
+ * to globally visible variables across the call.
+ *
+ * This macro only prevents the compiler from reordering reads and writes, it
+ * does not prevent the CPU from reordering reads and writes. However, all of
+ * the atomic operations that modify memory are full memory barriers.
+ *
+ * \threadsafety Obviously this macro is safe to use from any thread at any
+ *               time, but if you find yourself needing this, you are probably
+ *               dealing with some very sensitive code; be careful!
+ *
+ * \since This macro is available since SDL 3.1.3.
+ */
+#define SDL_CompilerBarrier() DoCompilerSpecificReadWriteBarrier()
+
+#elif defined(_MSC_VER) && (_MSC_VER > 1200) && !defined(__clang__)
+void _ReadWriteBarrier(void);
+#pragma intrinsic(_ReadWriteBarrier)
+#define SDL_CompilerBarrier()   _ReadWriteBarrier()
+#elif (defined(__GNUC__) && !defined(SDL_PLATFORM_EMSCRIPTEN)) || (defined(__SUNPRO_C) && (__SUNPRO_C >= 0x5120))
+/* This is correct for all CPUs when using GCC or Solaris Studio 12.1+. */
+#define SDL_CompilerBarrier()   __asm__ __volatile__ ("" : : : "memory")
+#elif defined(__WATCOMC__)
+extern __inline void SDL_CompilerBarrier(void);
+#pragma aux SDL_CompilerBarrier = "" parm [] modify exact [];
+#else
+#define SDL_CompilerBarrier()   \
+{ SDL_SpinLock _tmp = 0; SDL_LockSpinlock(&_tmp); SDL_UnlockSpinlock(&_tmp); }
+#endif
+
+/**
+ * Insert a memory release barrier (function version).
+ *
+ * Please refer to SDL_MemoryBarrierRelease for details. This is a function
+ * version, which might be useful if you need to use this functionality from a
+ * scripting language, etc. Also, some of the macro versions call this
+ * function behind the scenes, where more heavy lifting can happen inside of
+ * SDL. Generally, though, an app written in C/C++/etc should use the macro
+ * version, as it will be more efficient.
+ *
+ * \threadsafety Obviously this function is safe to use from any thread at any
+ *               time, but if you find yourself needing this, you are probably
+ *               dealing with some very sensitive code; be careful!
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_MemoryBarrierRelease
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_MemoryBarrierReleaseFunction(void);
+
+/**
+ * Insert a memory acquire barrier (function version).
+ *
+ * Please refer to SDL_MemoryBarrierRelease for details. This is a function
+ * version, which might be useful if you need to use this functionality from a
+ * scripting language, etc. Also, some of the macro versions call this
+ * function behind the scenes, where more heavy lifting can happen inside of
+ * SDL. Generally, though, an app written in C/C++/etc should use the macro
+ * version, as it will be more efficient.
+ *
+ * \threadsafety Obviously this function is safe to use from any thread at any
+ *               time, but if you find yourself needing this, you are probably
+ *               dealing with some very sensitive code; be careful!
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_MemoryBarrierAcquire
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_MemoryBarrierAcquireFunction(void);
+
+
+#ifdef SDL_WIKI_DOCUMENTATION_SECTION
+
+/**
+ * Insert a memory release barrier (macro version).
+ *
+ * Memory barriers are designed to prevent reads and writes from being
+ * reordered by the compiler and being seen out of order on multi-core CPUs.
+ *
+ * A typical pattern would be for thread A to write some data and a flag, and
+ * for thread B to read the flag and get the data. In this case you would
+ * insert a release barrier between writing the data and the flag,
+ * guaranteeing that the data write completes no later than the flag is
+ * written, and you would insert an acquire barrier between reading the flag
+ * and reading the data, to ensure that all the reads associated with the flag
+ * have completed.
+ *
+ * In this pattern you should always see a release barrier paired with an
+ * acquire barrier and you should gate the data reads/writes with a single
+ * flag variable.
+ *
+ * For more information on these semantics, take a look at the blog post:
+ * http://preshing.com/20120913/acquire-and-release-semantics
+ *
+ * This is the macro version of this functionality; if possible, SDL will use
+ * compiler intrinsics or inline assembly, but some platforms might need to
+ * call the function version of this, SDL_MemoryBarrierReleaseFunction to do
+ * the heavy lifting. Apps that can use the macro should favor it over the
+ * function.
+ *
+ * \threadsafety Obviously this macro is safe to use from any thread at any
+ *               time, but if you find yourself needing this, you are probably
+ *               dealing with some very sensitive code; be careful!
+ *
+ * \since This macro is available since SDL 3.1.3.
+ *
+ * \sa SDL_MemoryBarrierAcquire
+ * \sa SDL_MemoryBarrierReleaseFunction
+ */
+#define SDL_MemoryBarrierRelease() SDL_MemoryBarrierReleaseFunction()
+
+/**
+ * Insert a memory acquire barrier (macro version).
+ *
+ * Please see SDL_MemoryBarrierRelease for the details on what memory barriers
+ * are and when to use them.
+ *
+ * This is the macro version of this functionality; if possible, SDL will use
+ * compiler intrinsics or inline assembly, but some platforms might need to
+ * call the function version of this, SDL_MemoryBarrierAcquireFunction, to do
+ * the heavy lifting. Apps that can use the macro should favor it over the
+ * function.
+ *
+ * \threadsafety Obviously this macro is safe to use from any thread at any
+ *               time, but if you find yourself needing this, you are probably
+ *               dealing with some very sensitive code; be careful!
+ *
+ * \since This macro is available since SDL 3.1.3.
+ *
+ * \sa SDL_MemoryBarrierRelease
+ * \sa SDL_MemoryBarrierAcquireFunction
+ */
+#define SDL_MemoryBarrierAcquire() SDL_MemoryBarrierAcquireFunction()
+
+#elif defined(__GNUC__) && (defined(__powerpc__) || defined(__ppc__))
+#define SDL_MemoryBarrierRelease()   __asm__ __volatile__ ("lwsync" : : : "memory")
+#define SDL_MemoryBarrierAcquire()   __asm__ __volatile__ ("lwsync" : : : "memory")
+#elif defined(__GNUC__) && defined(__aarch64__)
+#define SDL_MemoryBarrierRelease()   __asm__ __volatile__ ("dmb ish" : : : "memory")
+#define SDL_MemoryBarrierAcquire()   __asm__ __volatile__ ("dmb ish" : : : "memory")
+#elif defined(__GNUC__) && defined(__arm__)
+#if 0 /* defined(SDL_PLATFORM_LINUX) || defined(SDL_PLATFORM_ANDROID) */
+/* Information from:
+   https://chromium.googlesource.com/chromium/chromium/+/trunk/base/atomicops_internals_arm_gcc.h#19
+
+   The Linux kernel provides a helper function which provides the right code for a memory barrier,
+   hard-coded at address 0xffff0fa0
+*/
+typedef void (*SDL_KernelMemoryBarrierFunc)();
+#define SDL_MemoryBarrierRelease()  ((SDL_KernelMemoryBarrierFunc)0xffff0fa0)()
+#define SDL_MemoryBarrierAcquire()  ((SDL_KernelMemoryBarrierFunc)0xffff0fa0)()
+#else
+#if defined(__ARM_ARCH_7__) || defined(__ARM_ARCH_7A__) || defined(__ARM_ARCH_7EM__) || defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7S__) || defined(__ARM_ARCH_8A__)
+#define SDL_MemoryBarrierRelease()   __asm__ __volatile__ ("dmb ish" : : : "memory")
+#define SDL_MemoryBarrierAcquire()   __asm__ __volatile__ ("dmb ish" : : : "memory")
+#elif defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) || defined(__ARM_ARCH_6K__) || defined(__ARM_ARCH_6T2__) || defined(__ARM_ARCH_6Z__) || defined(__ARM_ARCH_6ZK__)
+#ifdef __thumb__
+/* The mcr instruction isn't available in thumb mode, use real functions */
+#define SDL_MEMORY_BARRIER_USES_FUNCTION
+#define SDL_MemoryBarrierRelease()   SDL_MemoryBarrierReleaseFunction()
+#define SDL_MemoryBarrierAcquire()   SDL_MemoryBarrierAcquireFunction()
+#else
+#define SDL_MemoryBarrierRelease()   __asm__ __volatile__ ("mcr p15, 0, %0, c7, c10, 5" : : "r"(0) : "memory")
+#define SDL_MemoryBarrierAcquire()   __asm__ __volatile__ ("mcr p15, 0, %0, c7, c10, 5" : : "r"(0) : "memory")
+#endif /* __thumb__ */
+#else
+#define SDL_MemoryBarrierRelease()   __asm__ __volatile__ ("" : : : "memory")
+#define SDL_MemoryBarrierAcquire()   __asm__ __volatile__ ("" : : : "memory")
+#endif /* SDL_PLATFORM_LINUX || SDL_PLATFORM_ANDROID */
+#endif /* __GNUC__ && __arm__ */
+#else
+#if (defined(__SUNPRO_C) && (__SUNPRO_C >= 0x5120))
+/* This is correct for all CPUs on Solaris when using Solaris Studio 12.1+. */
+#include <mbarrier.h>
+#define SDL_MemoryBarrierRelease()  __machine_rel_barrier()
+#define SDL_MemoryBarrierAcquire()  __machine_acq_barrier()
+#else
+/* This is correct for the x86 and x64 CPUs, and we'll expand this over time. */
+#define SDL_MemoryBarrierRelease()  SDL_CompilerBarrier()
+#define SDL_MemoryBarrierAcquire()  SDL_CompilerBarrier()
+#endif
+#endif
+
+/* "REP NOP" is PAUSE, coded for tools that don't know it by that name. */
+#ifdef SDL_WIKI_DOCUMENTATION_SECTION
+
+/**
+ * A macro to insert a CPU-specific "pause" instruction into the program.
+ *
+ * This can be useful in busy-wait loops, as it serves as a hint to the CPU as
+ * to the program's intent; some CPUs can use this to do more efficient
+ * processing. On some platforms, this doesn't do anything, so using this
+ * macro might just be a harmless no-op.
+ *
+ * Note that if you are busy-waiting, there are often more-efficient
+ * approaches with other synchronization primitives: mutexes, semaphores,
+ * condition variables, etc.
+ *
+ * \threadsafety This macro is safe to use from any thread.
+ *
+ * \since This macro is available since SDL 3.1.3.
+ */
+#define SDL_CPUPauseInstruction() DoACPUPauseInACompilerAndArchitectureSpecificWay
+
+#elif (defined(__GNUC__) || defined(__clang__)) && (defined(__i386__) || defined(__x86_64__))
+    #define SDL_CPUPauseInstruction() __asm__ __volatile__("pause\n")  /* Some assemblers can't do REP NOP, so go with PAUSE. */
+#elif (defined(__arm__) && defined(__ARM_ARCH) && __ARM_ARCH >= 7) || defined(__aarch64__)
+    #define SDL_CPUPauseInstruction() __asm__ __volatile__("yield" ::: "memory")
+#elif (defined(__powerpc__) || defined(__powerpc64__))
+    #define SDL_CPUPauseInstruction() __asm__ __volatile__("or 27,27,27");
+#elif (defined(__riscv) && __riscv_xlen == 64)
+    #define SDL_CPUPauseInstruction() __asm__ __volatile__(".insn i 0x0F, 0, x0, x0, 0x010");
+#elif defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64))
+    #define SDL_CPUPauseInstruction() _mm_pause()  /* this is actually "rep nop" and not a SIMD instruction. No inline asm in MSVC x86-64! */
+#elif defined(_MSC_VER) && (defined(_M_ARM) || defined(_M_ARM64))
+    #define SDL_CPUPauseInstruction() __yield()
+#elif defined(__WATCOMC__) && defined(__386__)
+    extern __inline void SDL_CPUPauseInstruction(void);
+    #pragma aux SDL_CPUPauseInstruction = ".686p" ".xmm2" "pause"
+#else
+    #define SDL_CPUPauseInstruction()
+#endif
+
+
+/**
+ * A type representing an atomic integer value.
+ *
+ * This can be used to manage a value that is synchronized across multiple
+ * CPUs without a race condition; when an app sets a value with
+ * SDL_SetAtomicInt all other threads, regardless of the CPU it is running on,
+ * will see that value when retrieved with SDL_GetAtomicInt, regardless of CPU
+ * caches, etc.
+ *
+ * This is also useful for atomic compare-and-swap operations: a thread can
+ * change the value as long as its current value matches expectations. When
+ * done in a loop, one can guarantee data consistency across threads without a
+ * lock (but the usual warnings apply: if you don't know what you're doing, or
+ * you don't do it carefully, you can confidently cause any number of
+ * disasters with this, so in most cases, you _should_ use a mutex instead of
+ * this!).
+ *
+ * This is a struct so people don't accidentally use numeric operations on it
+ * directly. You have to use SDL atomic functions.
+ *
+ * \since This struct is available since SDL 3.1.3.
+ *
+ * \sa SDL_CompareAndSwapAtomicInt
+ * \sa SDL_GetAtomicInt
+ * \sa SDL_SetAtomicInt
+ * \sa SDL_AddAtomicInt
+ */
+typedef struct SDL_AtomicInt { int value; } SDL_AtomicInt;
+
+/**
+ * Set an atomic variable to a new value if it is currently an old value.
+ *
+ * ***Note: If you don't know what this function is for, you shouldn't use
+ * it!***
+ *
+ * \param a a pointer to an SDL_AtomicInt variable to be modified.
+ * \param oldval the old value.
+ * \param newval the new value.
+ * \returns true if the atomic variable was set, false otherwise.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_GetAtomicInt
+ * \sa SDL_SetAtomicInt
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_CompareAndSwapAtomicInt(SDL_AtomicInt *a, int oldval, int newval);
+
+/**
+ * Set an atomic variable to a value.
+ *
+ * This function also acts as a full memory barrier.
+ *
+ * ***Note: If you don't know what this function is for, you shouldn't use
+ * it!***
+ *
+ * \param a a pointer to an SDL_AtomicInt variable to be modified.
+ * \param v the desired value.
+ * \returns the previous value of the atomic variable.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_GetAtomicInt
+ */
+extern SDL_DECLSPEC int SDLCALL SDL_SetAtomicInt(SDL_AtomicInt *a, int v);
+
+/**
+ * Get the value of an atomic variable.
+ *
+ * ***Note: If you don't know what this function is for, you shouldn't use
+ * it!***
+ *
+ * \param a a pointer to an SDL_AtomicInt variable.
+ * \returns the current value of an atomic variable.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_SetAtomicInt
+ */
+extern SDL_DECLSPEC int SDLCALL SDL_GetAtomicInt(SDL_AtomicInt *a);
+
+/**
+ * Add to an atomic variable.
+ *
+ * This function also acts as a full memory barrier.
+ *
+ * ***Note: If you don't know what this function is for, you shouldn't use
+ * it!***
+ *
+ * \param a a pointer to an SDL_AtomicInt variable to be modified.
+ * \param v the desired value to add.
+ * \returns the previous value of the atomic variable.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_AtomicDecRef
+ * \sa SDL_AtomicIncRef
+ */
+extern SDL_DECLSPEC int SDLCALL SDL_AddAtomicInt(SDL_AtomicInt *a, int v);
+
+#ifndef SDL_AtomicIncRef
+
+/**
+ * Increment an atomic variable used as a reference count.
+ *
+ * ***Note: If you don't know what this macro is for, you shouldn't use it!***
+ *
+ * \param a a pointer to an SDL_AtomicInt to increment.
+ * \returns the previous value of the atomic variable.
+ *
+ * \threadsafety It is safe to call this macro from any thread.
+ *
+ * \since This macro is available since SDL 3.1.3.
+ *
+ * \sa SDL_AtomicDecRef
+ */
+#define SDL_AtomicIncRef(a)    SDL_AddAtomicInt(a, 1)
+#endif
+
+#ifndef SDL_AtomicDecRef
+
+/**
+ * Decrement an atomic variable used as a reference count.
+ *
+ * ***Note: If you don't know what this macro is for, you shouldn't use it!***
+ *
+ * \param a a pointer to an SDL_AtomicInt to increment.
+ * \returns true if the variable reached zero after decrementing, false
+ *          otherwise.
+ *
+ * \threadsafety It is safe to call this macro from any thread.
+ *
+ * \since This macro is available since SDL 3.1.3.
+ *
+ * \sa SDL_AtomicIncRef
+ */
+#define SDL_AtomicDecRef(a)    (SDL_AddAtomicInt(a, -1) == 1)
+#endif
+
+/**
+ * A type representing an atomic unsigned 32-bit value.
+ *
+ * This can be used to manage a value that is synchronized across multiple
+ * CPUs without a race condition; when an app sets a value with
+ * SDL_SetAtomicU32 all other threads, regardless of the CPU it is running on,
+ * will see that value when retrieved with SDL_GetAtomicU32, regardless of CPU
+ * caches, etc.
+ *
+ * This is also useful for atomic compare-and-swap operations: a thread can
+ * change the value as long as its current value matches expectations. When
+ * done in a loop, one can guarantee data consistency across threads without a
+ * lock (but the usual warnings apply: if you don't know what you're doing, or
+ * you don't do it carefully, you can confidently cause any number of
+ * disasters with this, so in most cases, you _should_ use a mutex instead of
+ * this!).
+ *
+ * This is a struct so people don't accidentally use numeric operations on it
+ * directly. You have to use SDL atomic functions.
+ *
+ * \since This struct is available since SDL 3.1.3.
+ *
+ * \sa SDL_CompareAndSwapAtomicU32
+ * \sa SDL_GetAtomicU32
+ * \sa SDL_SetAtomicU32
+ */
+typedef struct SDL_AtomicU32 { Uint32 value; } SDL_AtomicU32;
+
+/**
+ * Set an atomic variable to a new value if it is currently an old value.
+ *
+ * ***Note: If you don't know what this function is for, you shouldn't use
+ * it!***
+ *
+ * \param a a pointer to an SDL_AtomicU32 variable to be modified.
+ * \param oldval the old value.
+ * \param newval the new value.
+ * \returns true if the atomic variable was set, false otherwise.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_GetAtomicU32
+ * \sa SDL_SetAtomicU32
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_CompareAndSwapAtomicU32(SDL_AtomicU32 *a, Uint32 oldval, Uint32 newval);
+
+/**
+ * Set an atomic variable to a value.
+ *
+ * This function also acts as a full memory barrier.
+ *
+ * ***Note: If you don't know what this function is for, you shouldn't use
+ * it!***
+ *
+ * \param a a pointer to an SDL_AtomicU32 variable to be modified.
+ * \param v the desired value.
+ * \returns the previous value of the atomic variable.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_GetAtomicU32
+ */
+extern SDL_DECLSPEC Uint32 SDLCALL SDL_SetAtomicU32(SDL_AtomicU32 *a, Uint32 v);
+
+/**
+ * Get the value of an atomic variable.
+ *
+ * ***Note: If you don't know what this function is for, you shouldn't use
+ * it!***
+ *
+ * \param a a pointer to an SDL_AtomicU32 variable.
+ * \returns the current value of an atomic variable.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_SetAtomicU32
+ */
+extern SDL_DECLSPEC Uint32 SDLCALL SDL_GetAtomicU32(SDL_AtomicU32 *a);
+
+/**
+ * Set a pointer to a new value if it is currently an old value.
+ *
+ * ***Note: If you don't know what this function is for, you shouldn't use
+ * it!***
+ *
+ * \param a a pointer to a pointer.
+ * \param oldval the old pointer value.
+ * \param newval the new pointer value.
+ * \returns true if the pointer was set, false otherwise.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_CompareAndSwapAtomicInt
+ * \sa SDL_GetAtomicPointer
+ * \sa SDL_SetAtomicPointer
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_CompareAndSwapAtomicPointer(void **a, void *oldval, void *newval);
+
+/**
+ * Set a pointer to a value atomically.
+ *
+ * ***Note: If you don't know what this function is for, you shouldn't use
+ * it!***
+ *
+ * \param a a pointer to a pointer.
+ * \param v the desired pointer value.
+ * \returns the previous value of the pointer.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_CompareAndSwapAtomicPointer
+ * \sa SDL_GetAtomicPointer
+ */
+extern SDL_DECLSPEC void * SDLCALL SDL_SetAtomicPointer(void **a, void *v);
+
+/**
+ * Get the value of a pointer atomically.
+ *
+ * ***Note: If you don't know what this function is for, you shouldn't use
+ * it!***
+ *
+ * \param a a pointer to a pointer.
+ * \returns the current value of a pointer.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.1.3.
+ *
+ * \sa SDL_CompareAndSwapAtomicPointer
+ * \sa SDL_SetAtomicPointer
+ */
+extern SDL_DECLSPEC void * SDLCALL SDL_GetAtomicPointer(void **a);
+
+/* Ends C function definitions when using C++ */
+#ifdef __cplusplus
+}
+#endif
+
+#include <SDL3/SDL_close_code.h>
+
+#endif /* SDL_atomic_h_ */