add MouseMoveTimerTriggered to fix lagging touch drags

punker76 · Jun 9, 2022 · 7c5f6fe · 7c5f6fe
1 parent e6f1345
commit 7c5f6fe
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Showing 4 changed files with 68 additions and 7 deletions.
diff --git a/src/GongSolutions.WPF.DragDrop/DragDrop.Properties.cs b/src/GongSolutions.WPF.DragDrop/DragDrop.Properties.cs
@@ -1660,5 +1660,34 @@ public static void SetDropTargetItemsSorter(DependencyObject element, IDropTarge
         {
             element.SetValue(DropTargetItemsSorterProperty, value);
         }
+
+        /// <summary>
+        /// Gets or sets the mouse move triggerd by timer
+        /// </summary>
+        public static readonly DependencyProperty MouseMoveTimerTriggeredProperty
+            = DependencyProperty.RegisterAttached("MouseMoveTimerTriggered",
+                                                  typeof(bool),
+                                                  typeof(DragDrop),
+                                                  new PropertyMetadata(false));
+
+        /// <summary>Helper for getting <see cref="MouseMoveTimerTriggeredProperty"/> from <paramref name="element"/>.</summary>
+        /// <param name="element"><see cref="DependencyObject"/> to read <see cref="MouseMoveTimerTriggeredProperty"/> from.</param>
+        /// <remarks>Gets the mouse move triggerd by timer.</remarks>
+        /// <returns>MouseMoveTimerTriggeredProperty property value.</returns>
+        [AttachedPropertyBrowsableForType(typeof(UIElement))]
+        public static bool GetMouseMoveTimerTriggered(DependencyObject element)
+        {
+            return (bool)element.GetValue(MouseMoveTimerTriggeredProperty);
+        }
+
+        /// <summary>Helper for setting <see cref="MouseMoveTimerTriggeredProperty"/> on <paramref name="element"/>.</summary>
+        /// <param name="element"><see cref="DependencyObject"/> to set <see cref="MouseMoveTimerTriggeredProperty"/> on.</param>
+        /// <param name="value">SetMouseMoveTimerTriggered property value.</param>
+        /// <remarks>>Gets the mouse move triggerd by timer.</remarks>
+        [AttachedPropertyBrowsableForType(typeof(UIElement))]
+        public static void SetMouseMoveTimerTriggered(DependencyObject element, bool value)
+        {
+            element.SetValue(MouseMoveTimerTriggeredProperty, value);
+        }
     }
 }
diff --git a/src/GongSolutions.WPF.DragDrop/DragDrop.cs b/src/GongSolutions.WPF.DragDrop/DragDrop.cs
@@ -639,8 +639,8 @@ private static void DoDragSourceMove(object sender, Func<IInputElement, Point> g
                                     DragDropPreview?.Move(getPosition(DragDropPreview.PlacementTarget));
                                 }
 
-                                hookId = MouseHelper.HookMouseMove(point =>
-                                    {
+                                hookId = MouseHelper.HookMouseMove(DragDrop.GetMouseMoveTimerTriggered(dragInfo.VisualSource), 
+                                    point =>                                    {
                                         DragDropPreview?.Move(CursorHelper.GetCurrentCursorPosition(DragDropPreview.PlacementTarget, point));
                                         DragDropEffectPreview?.Move(CursorHelper.GetCurrentCursorPosition(DragDropEffectPreview.PlacementTarget, point));
                                     });

diff --git a/src/GongSolutions.WPF.DragDrop/Utilities/MouseHelper.cs b/src/GongSolutions.WPF.DragDrop/Utilities/MouseHelper.cs
@@ -11,29 +11,56 @@ internal static class MouseHelper
 
         private const int WH_MOUSE_LL = 14;
 
+        private static bool _TimerTriggerd;
         private static IntPtr _hookID = IntPtr.Zero;
         private static Action<System.Windows.Point> _mouseMoveHandler;
 
         // wee need to keep the variable to prevent the GarbageCollector to remove the HookCallback
         // https://social.msdn.microsoft.com/Forums/vstudio/en-US/68fdc3dc-8d77-48c4-875c-5312baa56aee/how-to-fix-callbackoncollecteddelegate-exception?forum=netfxbcl
         private static LowLevelMouseProc _proc = HookCallback;
+                private static System.Windows.Threading.DispatcherTimer _timer;
 
-        internal static IntPtr HookMouseMove(Action<System.Windows.Point> mouseMoveHandler)
+        internal static IntPtr HookMouseMove(bool TimerTriggerd, Action<System.Windows.Point> mouseMoveHandler)
         {
             _mouseMoveHandler = mouseMoveHandler;
+            _TimerTriggerd = TimerTriggerd;
 
-            using (var process = Process.GetCurrentProcess())
+            if (_TimerTriggerd)
             {
-                using (var module = process.MainModule)
+                _timer = new System.Windows.Threading.DispatcherTimer(System.Windows.Threading.DispatcherPriority.Input);
+                _timer.Tick += (sender, args) =>
                 {
-                    return SetWindowsHookEx(WH_MOUSE_LL, _proc, GetModuleHandle(module.ModuleName), 0);
+                    POINT lpPoint;
+                    if (GetCursorPos(out lpPoint))
+                        _mouseMoveHandler?.Invoke(new System.Windows.Point(lpPoint.x, lpPoint.y));
+                };
+                _timer.Interval = new TimeSpan(1);
+                _timer.Start();
+
+                return IntPtr.Zero;
+            }
+            else
+            {
+                using (var process = Process.GetCurrentProcess())
+                {
+                    using (var module = process.MainModule)
+                    {
+                        return SetWindowsHookEx(WH_MOUSE_LL, _proc, GetModuleHandle(module.ModuleName), 0);
+                    }
                 }
             }
         }
 
         internal static void RemoveHook(IntPtr hookId)
         {
-            UnhookWindowsHookEx(hookId);
+            if (_TimerTriggerd)
+            {
+                _timer.Stop();
+            }
+            else 
+            {
+                UnhookWindowsHookEx(hookId);
+            }            
         }
 
         private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
@@ -88,5 +115,8 @@ private struct MSLLHOOKSTRUCT
 
         [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
         private static extern IntPtr GetModuleHandle(string lpModuleName);
+
+        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
+        private static extern bool GetCursorPos(out POINT lpPoint);
     }
 }
diff --git a/src/Showcase/Views/ListBoxSamples.xaml b/src/Showcase/Views/ListBoxSamples.xaml
@@ -43,13 +43,15 @@
                                          dd:DragDrop.IsDragSource="True"
                                          dd:DragDrop.IsDropTarget="True"
                                          dd:DragDrop.UseDefaultEffectDataTemplate="True"
+                                         dd:DragDrop.MouseMoveTimerTriggered="True"
                                          ItemsSource="{Binding Data.Collection1}" />
                                 <ListBox x:Name="RightBoundListBox"
                                          Grid.Column="1"
                                          Grid.Row="0"
                                          dd:DragDrop.DropTargetAdornerBrush="Coral"
                                          dd:DragDrop.IsDragSource="True"
                                          dd:DragDrop.IsDropTarget="True"
+                                         dd:DragDrop.MouseMoveTimerTriggered="True"
                                          dd:DragDrop.ShowAlwaysDropTargetAdorner="True"
                                          ItemsSource="{Binding Data.Collection2}" />