Adding horizontal scroll support

MaterialDesignThemes.Wpf/ScrollViewerAssist.cs

@@ -1,5 +1,7 @@
-using System.Windows;
+using System;
+using System.Windows;
 using System.Windows.Controls;
+using System.Windows.Interop;
 
 namespace MaterialDesignThemes.Wpf
 {
@@ -69,5 +71,102 @@ public static bool GetShowSeparators(DependencyObject element)
         public static void SetIgnorePadding(DependencyObject element, bool value) => element.SetValue(IgnorePaddingProperty, value);
         public static bool GetIgnorePadding(DependencyObject element) => (bool)element.GetValue(IgnorePaddingProperty);
 
+        private static readonly DependencyProperty HorizontalScrollHookProperty = DependencyProperty.RegisterAttached(
+            "HorizontalScrollHook", typeof(HwndSourceHook), typeof(ScrollViewerAssist), new PropertyMetadata(null));
+
+        public static readonly DependencyProperty SupportHorizontalScrollProperty = DependencyProperty.RegisterAttached(
+            "SupportHorizontalScroll", typeof(bool), typeof(ScrollViewerAssist), new PropertyMetadata(false, OnSupportHorizontalScrollChanged));
+
+        private static void OnSupportHorizontalScrollChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
+        {
+            //Based on: https://blog.walterlv.com/post/handle-horizontal-scrolling-of-touchpad-en.html
+            if (d is ScrollViewer scrollViewer)
+            {
+                if ((bool)e.NewValue)
+                {
+                    OnLoaded(scrollViewer, sv =>
+                    {
+                        if (GetSupportHorizontalScroll(sv))
+                        {
+                            RegisterHook(sv);
+                        }
+                    });
+                }
+                else
+                {
+                    OnLoaded(scrollViewer, sv =>
+                    {
+                        if (!GetSupportHorizontalScroll(sv))
+                        {
+                            RemoveHook(sv);
+                        }
+                    });
+                }
+            }
+
+            static void OnLoaded(ScrollViewer scrollViewer, Action<ScrollViewer> doOnLoaded)
+            {
+                if(scrollViewer.IsLoaded)
+                {
+                    doOnLoaded(scrollViewer);
+                }
+                else
+                {
+                    RoutedEventHandler? onLoaded = null;
+                    onLoaded = (_, _) =>
+                    {
+                        scrollViewer.Loaded -= onLoaded;
+                        doOnLoaded(scrollViewer);
+                    };
+                    scrollViewer.Loaded += onLoaded;
+                }
+            }
+
+            static void RemoveHook(ScrollViewer scrollViewer)
+            {
+                if (scrollViewer.GetValue(HorizontalScrollHookProperty) is HwndSourceHook hook &&
+                    PresentationSource.FromVisual(scrollViewer) is HwndSource source)
+                {
+                    source.RemoveHook(hook);
+                    scrollViewer.SetValue(HorizontalScrollHookProperty, null);
+                }
+            }
+
+            static void RegisterHook(ScrollViewer scrollViewer)
+            {
+                RemoveHook(scrollViewer);
+                if (PresentationSource.FromVisual(scrollViewer) is HwndSource source)
+                {
+                    HwndSourceHook hook = Hook;
+                    scrollViewer.SetValue(HorizontalScrollHookProperty, hook);
+                    source.AddHook(hook);
+                }
+
+                IntPtr Hook(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
+                {
+                    const int WM_MOUSEHWHEEL = 0x020E;
+                    switch (msg)
+                    {
+                        case WM_MOUSEHWHEEL:
+                            int tilt = (short)((wParam.ToInt32() >> 16) & 0xFFFF);
+                            OnMouseTilt(tilt);
+                            return (IntPtr)1;
+                    }
+                    return IntPtr.Zero;
+                }
+
+                void OnMouseTilt(int tilt)
+                {
+                    scrollViewer.ScrollToHorizontalOffset(scrollViewer.HorizontalOffset + tilt);
+                }
+            }
+        }
+
+        public static void SetSupportHorizontalScroll(DependencyObject element, bool value)
+            => element.SetValue(SupportHorizontalScrollProperty, value);
+
+        public static bool GetSupportHorizontalScroll(DependencyObject element)
+            => (bool)element.GetValue(SupportHorizontalScrollProperty);
+
     }
 }

MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.TabControl.xaml

@@ -51,6 +51,7 @@
                                 Background="{TemplateBinding wpf:ColorZoneAssist.Background}"
                                 Focusable="False">
                                 <ScrollViewer
+                                    wpf:ScrollViewerAssist.SupportHorizontalScroll="True"
                                     HorizontalScrollBarVisibility="Hidden"
                                     VerticalScrollBarVisibility="Hidden">
                                     <StackPanel>