Merge pull request #302 from Frassle/mouse

[Win32] Fix spurious mouse enter and leave messages

Source/OpenTK/Platform/Windows/WinGLNative.cs

@@ -70,6 +70,7 @@ namespace OpenTK.Platform.Windows
         bool borderless_maximized_window_state = false; // Hack to get maximized mode with hidden border (not normally possible).
         bool focused;
         bool mouse_outside_window = true;
+        int mouse_capture_count = 0;
         int mouse_last_timestamp = 0;
         bool invisible_since_creation; // Set by WindowsMessage.CREATE and consumed by Visible = true (calls BringWindowToFront).
         int suppress_resize; // Used in WindowBorder and WindowState in order to avoid rapid, consecutive resize events.
@@ -384,6 +385,14 @@ namespace OpenTK.Platform.Windows
             return null;
         }
 
+        private void HandleCaptureChanged(IntPtr handle, WindowMessage message, IntPtr wParam, IntPtr lParam)
+        {
+            if (lParam != window.Handle)
+            {
+                mouse_capture_count = 0;
+            }
+        }
+
         void HandleChar(IntPtr handle, WindowMessage message, IntPtr wParam, IntPtr lParam)
         {
             char c;
@@ -400,12 +409,40 @@ namespace OpenTK.Platform.Windows
 
         void HandleMouseMove(IntPtr handle, WindowMessage message, IntPtr wParam, IntPtr lParam)
         {
+            Point point = new Point(
+                (short)((uint)lParam.ToInt32() & 0x0000FFFF),
+                (short)(((uint)lParam.ToInt32() & 0xFFFF0000) >> 16));
+
+            if (mouse_capture_count > 0)
+            {
+                bool mouse_was_outside_window = mouse_outside_window;
+                mouse_outside_window = !ClientRectangle.Contains(point);
+
+                if (mouse_outside_window && !mouse_was_outside_window)
+                {
+                    // Mouse leaving
+                    // If we have mouse capture we ignore WM_MOUSELEAVE events, so 
+                    // have to manually call OnMouseLeave here.
+                    // Mouse tracking is disabled automatically by the OS
+                    OnMouseLeave(EventArgs.Empty);
+                } 
+                else if (!mouse_outside_window && mouse_was_outside_window)
+                {
+                    // Mouse entring
+                    OnMouseEnter(EventArgs.Empty);
+                }
+            }
+            else if (/* !mouse_is_captured && */ mouse_outside_window)
+            {
+                // Once we receive a mouse move event, it means that the mouse has
+                // re-entered the window.
+                mouse_outside_window = false;
+                EnableMouseTracking();
+                OnMouseEnter(EventArgs.Empty);
+            }
+
             unsafe
             {
-                Point point = new Point(
-                    (short)((uint)lParam.ToInt32() & 0x0000FFFF),
-                    (short)(((uint)lParam.ToInt32() & 0xFFFF0000) >> 16));
-
                 // GetMouseMovePointsEx works with screen coordinates
                 Point screenPoint = point;
                 Functions.ClientToScreen(handle, ref screenPoint);
@@ -479,24 +516,18 @@ namespace OpenTK.Platform.Windows
                 }
                 mouse_last_timestamp = timestamp;
             }
-
-            if (mouse_outside_window)
-            {
-                // Once we receive a mouse move event, it means that the mouse has
-                // re-entered the window.
-                mouse_outside_window = false;
-                EnableMouseTracking();
-
-                OnMouseEnter(EventArgs.Empty);
-            }
         }
 
         void HandleMouseLeave(IntPtr handle, WindowMessage message, IntPtr wParam, IntPtr lParam)
         {
-            mouse_outside_window = true;
+            // If the mouse is captured we get spurious MOUSELEAVE events.
-            // Mouse tracking is disabled automatically by the OS
+            // So ignore WM_MOUSELEAVE if capture count != 0.
-
+            if (mouse_capture_count == 0 )
-            OnMouseLeave(EventArgs.Empty);
+            {
+                mouse_outside_window = true;
+                // Mouse tracking is disabled automatically by the OS
+                OnMouseLeave(EventArgs.Empty);
+            }
         }
 
         void HandleMouseWheel(IntPtr handle, WindowMessage message, IntPtr wParam, IntPtr lParam)
@@ -515,25 +546,25 @@ namespace OpenTK.Platform.Windows
 
         void HandleLButtonDown(IntPtr handle, WindowMessage message, IntPtr wParam, IntPtr lParam)
         {
-            Functions.SetCapture(window.Handle);
+            SetCapture();
             OnMouseDown(MouseButton.Left);
         }
 
         void HandleMButtonDown(IntPtr handle, WindowMessage message, IntPtr wParam, IntPtr lParam)
         {
-            Functions.SetCapture(window.Handle);
+            SetCapture();
             OnMouseDown(MouseButton.Middle);
         }
 
         void HandleRButtonDown(IntPtr handle, WindowMessage message, IntPtr wParam, IntPtr lParam)
         {
-            Functions.SetCapture(window.Handle);
+            SetCapture();
             OnMouseDown(MouseButton.Right);
         }
 
         void HandleXButtonDown(IntPtr handle, WindowMessage message, IntPtr wParam, IntPtr lParam)
         {
-            Functions.SetCapture(window.Handle);
+            SetCapture();
             MouseButton button =
                 ((wParam.ToInt32() & 0xFFFF0000) >> 16) == 1 ?
                 MouseButton.Button1 : MouseButton.Button2;
@@ -542,25 +573,25 @@ namespace OpenTK.Platform.Windows
 
         void HandleLButtonUp(IntPtr handle, WindowMessage message, IntPtr wParam, IntPtr lParam)
         {
-            Functions.ReleaseCapture();
+            ReleaseCapture();
             OnMouseUp(MouseButton.Left);
         }
 
         void HandleMButtonUp(IntPtr handle, WindowMessage message, IntPtr wParam, IntPtr lParam)
         {
-            Functions.ReleaseCapture();
+            ReleaseCapture();
             OnMouseUp(MouseButton.Middle);
         }
 
         void HandleRButtonUp(IntPtr handle, WindowMessage message, IntPtr wParam, IntPtr lParam)
         {
-            Functions.ReleaseCapture();
+            ReleaseCapture();
             OnMouseUp(MouseButton.Right);
         }
 
         void HandleXButtonUp(IntPtr handle, WindowMessage message, IntPtr wParam, IntPtr lParam)
         {
-            Functions.ReleaseCapture();
+            ReleaseCapture();
             MouseButton button =
                 ((wParam.ToInt32() & 0xFFFF0000) >> 16) == 1 ?
                 MouseButton.Button1 : MouseButton.Button2;
@@ -694,6 +725,10 @@ namespace OpenTK.Platform.Windows
                     result = HandleSetCursor(handle, message, wParam, lParam);
                     break;
 
+                case WindowMessage.CAPTURECHANGED:
+                    HandleCaptureChanged(handle, message, wParam, lParam);
+                    break;
+
                 #endregion
 
                 #region Input events
@@ -794,6 +829,26 @@ namespace OpenTK.Platform.Windows
             }
         }
 
+        private void SetCapture()
+        {
+            if (mouse_capture_count == 0)
+            {
+                Functions.SetCapture(window.Handle);
+            }
+            mouse_capture_count++;
+        }
+
+        private void ReleaseCapture()
+        {
+            mouse_capture_count--;
+            if (mouse_capture_count == 0)
+            {
+                Functions.ReleaseCapture();
+                // Renable mouse tracking
+                EnableMouseTracking();
+            }
+        }
+
         private void EnableMouseTracking()
         {
             TrackMouseEventStructure me = new TrackMouseEventStructure();