RawInput: fix input latching when dragging and switching between windows

Source/Editor/GUI/Docking/DockHintWindow.cs

@@ -346,6 +346,10 @@ namespace FlaxEditor.GUI.Docking
         {
             if (button == MouseButton.Left)
             {
+                // Workaround to make sure the mouse down event which initiated dragging in moved window gets properly
+                // released when this window gets destroyed.
+                _toMove.Window.Window.Internal_OnMouseUp(ref location, button);
+
                 Dispose();
             }
         }

Source/Engine/Platform/Windows/WindowsInput.cpp

@@ -112,7 +112,13 @@ namespace WindowsInputImpl
     bool XInputGamepads[XUSER_MAX_COUNT] = { false };
     WindowsMouse* Mouse = nullptr;
     WindowsKeyboard* Keyboard = nullptr;
-    bool RawInputEnabled = true;
+}
+
+namespace WindowsRawInputImpl
+{
+    bool UseRawInput = true;
+    Window* LastLeaveWindow = nullptr;
+    Window* CurrentInputWindow = nullptr;
 }
 
 void WindowsInput::Init()
@@ -120,7 +126,7 @@ void WindowsInput::Init()
     Input::Mouse = WindowsInputImpl::Mouse = New<WindowsMouse>();
     Input::Keyboard = WindowsInputImpl::Keyboard = New<WindowsKeyboard>();
 
-    if (WindowsInputImpl::RawInputEnabled)
+    if (WindowsRawInputImpl::UseRawInput)
     {
         RAWINPUTDEVICE rid[2] = {};
 
@@ -176,6 +182,8 @@ bool WindowsInput::WndProc(Window* window, Windows::UINT msg, Windows::WPARAM wP
 
 bool OnRawInput(Vector2 mousePosition, Window* window, HRAWINPUT input)
 {
+    // TODO: use GetRawInputBuffer to avoid filling the message queue with high polling rate mice
+
     static BYTE* dataBuffer = nullptr;
     static uint32 dataBufferSize = 0;
 
@@ -191,6 +199,13 @@ bool OnRawInput(Vector2 mousePosition, Window* window, HRAWINPUT input)
 
     GetRawInputData(input, RID_INPUT, dataBuffer, &dataSize, sizeof(RAWINPUTHEADER));
 
+    // Workaround to send the input to the topmost window after focusing the window from other applications.
+    if (WindowsRawInputImpl::LastLeaveWindow == window || WindowsRawInputImpl::LastLeaveWindow == nullptr)
+    {
+        if (WindowsRawInputImpl::CurrentInputWindow != nullptr)
+            window = WindowsRawInputImpl::CurrentInputWindow;
+    }
+
     const RAWINPUT* rawInput = reinterpret_cast<RAWINPUT*>(dataBuffer);
     if (rawInput->header.dwType == RIM_TYPEKEYBOARD)
     {
@@ -227,11 +242,8 @@ bool OnRawInput(Vector2 mousePosition, Window* window, HRAWINPUT input)
             mousePos += mouseDelta;
 
             if (!mouseDelta.IsZero())
-            {
-                //Input::Mouse->OnMouseMove(mousePos, window);
                 Input::Mouse->OnMouseMoveDelta(mouseDelta, window);
         }
-        }
 
         if ((rawMouse.usButtonFlags & RI_MOUSE_LEFT_BUTTON_DOWN) != 0)
             Input::Mouse->OnMouseDown(mousePos, MouseButton::Left, window);
@@ -268,7 +280,7 @@ bool OnRawInput(Vector2 mousePosition, Window* window, HRAWINPUT input)
 
 bool WindowsKeyboard::WndProc(Window* window, const Windows::UINT msg, Windows::WPARAM wParam, Windows::LPARAM lParam)
 {
-    if (WindowsInputImpl::RawInputEnabled && WndProcRawInput(window, msg, wParam, lParam))
+    if (WindowsRawInputImpl::UseRawInput && WndProcRawInput(window, msg, wParam, lParam))
         return true;
 
     bool result = false;
@@ -324,7 +336,7 @@ bool WindowsKeyboard::WndProcRawInput(Window* window, const Windows::UINT msg, W
 
 bool WindowsMouse::WndProc(Window* window, const UINT msg, WPARAM wParam, LPARAM lParam)
 {
-    if (WindowsInputImpl::RawInputEnabled && WndProcRawInput(window, msg, wParam, lParam))
+    if (WindowsRawInputImpl::UseRawInput && WndProcRawInput(window, msg, wParam, lParam))
         return true;
 
     bool result = false;
@@ -341,6 +353,9 @@ bool WindowsMouse::WndProc(Window* window, const UINT msg, WPARAM wParam, LPARAM
     {
     case WM_MOUSEMOVE:
     {
+        if (!WindowsRawInputImpl::UseRawInput)
+        {
+            // Calculate mouse deltas since last message
             static Vector2 lastPos = mousePos;
             if (_state.MouseWasReset)
             {
@@ -352,6 +367,7 @@ bool WindowsMouse::WndProc(Window* window, const UINT msg, WPARAM wParam, LPARAM
             if (!deltaPos.IsZero())
                 OnMouseMoveDelta(deltaPos, window);
             lastPos = mousePos;
+        }
 
         OnMouseMove(mousePos, window);
         result = true;
@@ -475,11 +491,15 @@ bool WindowsMouse::WndProcRawInput(Window* window, const UINT msg, WPARAM wParam
     case WM_MOUSEWHEEL:
     {
         // Ignored with raw input
+        WindowsRawInputImpl::CurrentInputWindow = window;
         result = true;
         break;
     }
     case WM_MOUSEMOVE:
-    case WM_MOUSELEAVE:
+    {
+        WindowsRawInputImpl::CurrentInputWindow = window;
+        break;
+    }
     case WM_LBUTTONDBLCLK:
     case WM_RBUTTONDBLCLK:
     case WM_MBUTTONDBLCLK:
@@ -487,6 +507,21 @@ bool WindowsMouse::WndProcRawInput(Window* window, const UINT msg, WPARAM wParam
         // Might need to be handled here
         break;
     }
+    case WM_MOUSELEAVE:
+    {
+        WindowsRawInputImpl::LastLeaveWindow = window;
+        break;
+    }
+    case WM_ACTIVATE:
+    {
+        break;
+    }
+    case WM_ACTIVATEAPP:
+    {
+        // Reset when switching between apps
+        WindowsRawInputImpl::LastLeaveWindow = nullptr;
+        break;
+    }
     case WM_INPUT:
     {
         result = OnRawInput(_state.MousePosition, window, reinterpret_cast<HRAWINPUT>(lParam));