From 8a34ae3ece1a0c30a4755e3ebb3eda0901f33973 Mon Sep 17 00:00:00 2001
From: MineBill <minebill@protonmail.com>
Date: Sun, 1 Oct 2023 18:41:32 +0300
Subject: [PATCH] Handle double clicking to eliminate perceived lag.

---
 Source/Engine/UI/GUI/Common/Button.cs    | 22 ++++++++++++++++++++++
 Source/Engine/UI/GUI/Common/CheckBox.cs  | 21 +++++++++++++++++++++
 Source/Engine/UI/GUI/Common/Dropdown.cs  | 24 ++++++++++++++++++++++++
 Source/Engine/UI/GUI/Panels/DropPanel.cs | 23 +++++++++++++++++++++++
 4 files changed, 90 insertions(+)

diff --git a/Source/Engine/UI/GUI/Common/Button.cs b/Source/Engine/UI/GUI/Common/Button.cs
index b50f3dd46..02337411b 100644
--- a/Source/Engine/UI/GUI/Common/Button.cs
+++ b/Source/Engine/UI/GUI/Common/Button.cs
@@ -314,6 +314,28 @@ namespace FlaxEngine.GUI
             return false;
         }
 
+        /// <inheritdoc />
+        public override bool OnMouseDoubleClick(Float2 location, MouseButton button)
+        {
+            if (base.OnMouseDoubleClick(location, button))
+                return true;
+
+            if (button == MouseButton.Left && _isPressed)
+            {
+                OnPressEnd();
+                OnClick();
+                return true;
+            }
+            
+            if (button == MouseButton.Left && !_isPressed)
+            {
+                OnPressBegin();
+                return true;
+            }
+
+            return false;
+        }
+
         /// <inheritdoc />
         public override bool OnTouchDown(Float2 location, int pointerId)
         {
diff --git a/Source/Engine/UI/GUI/Common/CheckBox.cs b/Source/Engine/UI/GUI/Common/CheckBox.cs
index 2f1ff42a9..2128c0311 100644
--- a/Source/Engine/UI/GUI/Common/CheckBox.cs
+++ b/Source/Engine/UI/GUI/Common/CheckBox.cs
@@ -277,6 +277,27 @@ namespace FlaxEngine.GUI
             return base.OnMouseDown(location, button);
         }
 
+        /// <inheritdoc />
+        public override bool OnMouseDoubleClick(Float2 location, MouseButton button)
+        {
+            if (button == MouseButton.Left && !_isPressed)
+            {
+                OnPressBegin();
+                return true;
+            }
+            
+            if (button == MouseButton.Left && _isPressed)
+            {
+                OnPressEnd();
+                if (_box.Contains(ref location))
+                {
+                    OnClick();
+                    return true;
+                }
+            }
+            return base.OnMouseDoubleClick(location, button);
+        }
+
         /// <inheritdoc />
         public override bool OnMouseUp(Float2 location, MouseButton button)
         {
diff --git a/Source/Engine/UI/GUI/Common/Dropdown.cs b/Source/Engine/UI/GUI/Common/Dropdown.cs
index 6ad962d6d..aea4e173a 100644
--- a/Source/Engine/UI/GUI/Common/Dropdown.cs
+++ b/Source/Engine/UI/GUI/Common/Dropdown.cs
@@ -666,6 +666,30 @@ namespace FlaxEngine.GUI
             return false;
         }
 
+        /// <inheritdoc />
+        public override bool OnMouseDoubleClick(Float2 location, MouseButton button)
+        {
+            if (base.OnMouseDoubleClick(location, button))
+                return true;
+            
+            if (_touchDown && button == MouseButton.Left)
+            {
+                _touchDown = false;
+                ShowPopup();
+                return true;
+            }
+            
+            if (button == MouseButton.Left)
+            {
+                _touchDown = true;
+                if (!IsPopupOpened)
+                    Focus();
+                return true;
+            }
+
+            return false;
+        }
+
         /// <inheritdoc />
         public override bool OnTouchDown(Float2 location, int pointerId)
         {
diff --git a/Source/Engine/UI/GUI/Panels/DropPanel.cs b/Source/Engine/UI/GUI/Panels/DropPanel.cs
index d650d6205..66e7413eb 100644
--- a/Source/Engine/UI/GUI/Panels/DropPanel.cs
+++ b/Source/Engine/UI/GUI/Panels/DropPanel.cs
@@ -501,6 +501,29 @@ namespace FlaxEngine.GUI
             return false;
         }
 
+        /// <inheritdoc />
+        public override bool OnMouseDoubleClick(Float2 location, MouseButton button)
+        {
+            if (base.OnMouseDoubleClick(location, button))
+                return true;
+            
+            _mouseOverHeader = HeaderRectangle.Contains(location);
+            if (button == MouseButton.Left && _mouseOverHeader)
+            {
+                _mouseButtonLeftDown = true;
+                return true;
+            }
+
+            if (button == MouseButton.Left && _mouseButtonLeftDown)
+            {
+                _mouseButtonLeftDown = false;
+                if (_mouseOverHeader)
+                    Toggle();
+                return true;
+            }
+            return false;
+        }
+
         /// <inheritdoc />
         public override void OnMouseLeave()
         {