Fix issue by for BubbleVerticalScroll

Author: nicolaihenriksen

src/MaterialDesignThemes.Wpf/ScrollViewerAssist.cs

@@ -1,4 +1,4 @@
-using System.Windows.Interop;
+using System.Windows.Interop;
 
 namespace MaterialDesignThemes.Wpf;
 
@@ -67,6 +67,9 @@ public static PaddingMode GetPaddingMode(DependencyObject element)
     private static readonly DependencyProperty HorizontalScrollSourceProperty = DependencyProperty.RegisterAttached(
         "HorizontalScrollSource", typeof(HwndSource), typeof(ScrollViewerAssist), new PropertyMetadata(null));
 
+    private static readonly DependencyProperty BubbleVerticalScrollHookProperty = DependencyProperty.RegisterAttached(
+        "BubbleVerticalScrollHook", typeof(HwndSourceHook), typeof(ScrollViewerAssist), new PropertyMetadata(null));
+
     public static readonly DependencyProperty SupportHorizontalScrollProperty = DependencyProperty.RegisterAttached(
         "SupportHorizontalScroll", typeof(bool), typeof(ScrollViewerAssist), new PropertyMetadata(false, OnSupportHorizontalScrollChanged));
 
@@ -114,6 +117,12 @@ static void OnUnloaded(object? sender, RoutedEventArgs e)
             }
         }
 
+        static void RemoveHandlers(ScrollViewer scrollViewer)
+        {
+            WeakEventManager<ScrollViewer, RoutedEventArgs>.RemoveHandler(scrollViewer, nameof(ScrollViewer.Loaded), OnLoaded);
+            WeakEventManager<ScrollViewer, RoutedEventArgs>.RemoveHandler(scrollViewer, nameof(ScrollViewer.Unloaded), OnUnloaded);
+        }
+
         static void RemoveHook(ScrollViewer scrollViewer)
         {
             if (scrollViewer.GetValue(HorizontalScrollHookProperty) is HwndSourceHook hook &&
@@ -138,12 +147,20 @@ static void RegisterHook(ScrollViewer scrollViewer)
             IntPtr Hook(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
             {
                 const int WM_MOUSEHWHEEL = 0x020E;
+                const int WM_DESTROY = 0x0002;
+                const int WM_NCDESTROY = 0x0082;
                 switch (msg)
                 {
                     case WM_MOUSEHWHEEL when scrollViewer.IsMouseOver:
                         int tilt = (short)((wParam.ToInt64() >> 16) & 0xFFFF);
                         scrollViewer.ScrollToHorizontalOffset(scrollViewer.HorizontalOffset + tilt);
                         return (IntPtr)1;
+                    case WM_DESTROY:
+                    case WM_NCDESTROY:
+                        RemoveHandlers(scrollViewer);
+                        var source = PresentationSource.FromVisual(scrollViewer) as HwndSource;
+                        source?.RemoveHook(Hook);
+                        break;
                 }
                 return IntPtr.Zero;
             }
@@ -152,19 +169,19 @@ IntPtr Hook(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled
 
     public static readonly DependencyProperty BubbleVerticalScrollProperty = DependencyProperty.RegisterAttached(
         "BubbleVerticalScroll", typeof(bool), typeof(ScrollViewerAssist), new PropertyMetadata(false, OnBubbleVerticalScrollChanged));
-
+    
     private static void OnBubbleVerticalScrollChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
     {
-        if (d is ScrollViewer scrollViewer)
+        if (d is ScrollViewer sv)
         {
-            if (scrollViewer.IsLoaded)
+            if (sv.IsLoaded)
             {
-                DoOnLoaded(scrollViewer);
+                DoOnLoaded(sv);
             }
             else
             {
-                WeakEventManager<ScrollViewer, RoutedEventArgs>.AddHandler(scrollViewer, nameof(ScrollViewer.Loaded), OnLoaded);
-                WeakEventManager<ScrollViewer, RoutedEventArgs>.AddHandler(scrollViewer, nameof(ScrollViewer.Unloaded), OnUnloaded);
+                RegisterForLoadedEvent(sv);
+                RegisterForUnloadedEvent(sv);
             }
         }
 
@@ -176,10 +193,48 @@ static void OnLoaded(object? sender, RoutedEventArgs e)
             }
         }
 
+        static void UnregisterForLoadedEvent(ScrollViewer sv)
+        {
+            WeakEventManager<ScrollViewer, RoutedEventArgs>.RemoveHandler(sv, nameof(ScrollViewer.Loaded), OnLoaded);
+        }
+
+        static void RegisterForLoadedEvent(ScrollViewer sv)
+        {
+            // Avoid double registrations
+            UnregisterForLoadedEvent(sv);
+            WeakEventManager<ScrollViewer, RoutedEventArgs>.AddHandler(sv, nameof(ScrollViewer.Loaded), OnLoaded);
+        }
+
+        static void UnregisterForUnloadedEvent(ScrollViewer sv)
+        {
+            WeakEventManager<ScrollViewer, RoutedEventArgs>.RemoveHandler(sv, nameof(ScrollViewer.Unloaded), OnUnloaded);
+        }
+
+        static void RegisterForUnloadedEvent(ScrollViewer sv)
+        {
+            // Avoid double registrations
+            UnregisterForUnloadedEvent(sv);
+            WeakEventManager<ScrollViewer, RoutedEventArgs>.AddHandler(sv, nameof(ScrollViewer.Unloaded), OnUnloaded);
+        }
+
+        static void UnregisterForMouseWheelEvent(ScrollViewer sv)
+        {
+            sv.RemoveHandler(UIElement.MouseWheelEvent, (RoutedEventHandler)ScrollViewerOnMouseWheel);
+        }
+
+        static void RegisterForMouseWheelEvent(ScrollViewer sv)
+        {
+            // Avoid double registrations
+            UnregisterForMouseWheelEvent(sv);
+            sv.AddHandler(UIElement.MouseWheelEvent, (RoutedEventHandler)ScrollViewerOnMouseWheel, true);
+        }
+
         static void DoOnLoaded(ScrollViewer sv)
         {
             if (GetBubbleVerticalScroll(sv))
             {
+                RegisterForUnloadedEvent(sv);
+                RegisterForMouseWheelEvent(sv);
                 RegisterHook(sv);
             }
             else
@@ -192,29 +247,55 @@ static void OnUnloaded(object? sender, RoutedEventArgs e)
         {
             if (sender is ScrollViewer sv)
             {
-                RemoveHook(sv);
+                UnregisterForUnloadedEvent(sv);
+                UnregisterForMouseWheelEvent(sv);
             }
         }
 
-        static void RemoveHook(ScrollViewer scrollViewer)
+        static void RemoveHook(ScrollViewer sv)
         {
-            scrollViewer.RemoveHandler(UIElement.MouseWheelEvent, (RoutedEventHandler)ScrollViewerOnMouseWheel);
+            var source = PresentationSource.FromVisual(sv) as HwndSource;
+            if (source is not null && sv.GetValue(BubbleVerticalScrollHookProperty) is HwndSourceHook hook)
+            {
+                source.RemoveHook(hook);
+                sv.SetValue(BubbleVerticalScrollHookProperty, null);
+            }
         }
 
-        static void RegisterHook(ScrollViewer scrollViewer)
+        static void RegisterHook(ScrollViewer sv)
         {
-            RemoveHook(scrollViewer);
-            scrollViewer.AddHandler(UIElement.MouseWheelEvent, (RoutedEventHandler)ScrollViewerOnMouseWheel, true);
+            RemoveHook(sv);
+            if (PresentationSource.FromVisual(sv) is HwndSource source)
+            {
+                HwndSourceHook hook = Hook;
+                source.AddHook(hook);
+                sv.SetValue(BubbleVerticalScrollHookProperty, hook);
+            }
+
+            IntPtr Hook(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
+            {
+                const int WM_DESTROY = 0x0002;
+                const int WM_NCDESTROY = 0x0082;
+                switch (msg)
+                {
+                    case WM_DESTROY:
+                    case WM_NCDESTROY:
+                        UnregisterForMouseWheelEvent(sv);
+                        UnregisterForLoadedEvent(sv);
+                        UnregisterForUnloadedEvent(sv);
+                        RemoveHook(sv);
+                        break;
+                }
+                return IntPtr.Zero;
+            }
         }
 
         // This relay is only needed because the UIElement.AddHandler() has strict requirements for the signature of the passed Delegate
-        static void ScrollViewerOnMouseWheel(object sender, RoutedEventArgs e) => HandleMouseWheel(sender, (MouseWheelEventArgs)e);
+        static void ScrollViewerOnMouseWheel(object? sender, RoutedEventArgs e) => HandleMouseWheel(sender, (MouseWheelEventArgs)e);
 
-        static void HandleMouseWheel(object sender, MouseWheelEventArgs e)
+        static void HandleMouseWheel(object? sender, MouseWheelEventArgs e)
         {
-            var scrollViewer = (ScrollViewer)sender;
-
-            if (scrollViewer.GetVisualAncestry().Skip(1).FirstOrDefault() is not UIElement parentUiElement)
+            if (sender is not ScrollViewer sv || sv.GetVisualAncestry().Skip(1).FirstOrDefault() is not UIElement parentUiElement)
                 return;
 
             // Re-raise the mouse wheel event on the visual parent to bubble it upwards