From 4b277194989c02b9fd44569ca2acb0ed65907e36 Mon Sep 17 00:00:00 2001
From: victor <vicdotexe@gmail.com>
Date: Sat, 19 Oct 2024 14:00:45 -0700
Subject: [PATCH] attached behavior for scroll viewers to throttle touch pad
 scrolling

---
 .../Converters/ScrollThrottleBehavior.cs      | 43 +++++++++++++++++++
 FRBDK/Glue/Glue/Themes/Frb.Styles.xaml        |  4 +-
 2 files changed, 46 insertions(+), 1 deletion(-)
 create mode 100644 FRBDK/Glue/Glue/Themes/Converters/ScrollThrottleBehavior.cs

diff --git a/FRBDK/Glue/Glue/Themes/Converters/ScrollThrottleBehavior.cs b/FRBDK/Glue/Glue/Themes/Converters/ScrollThrottleBehavior.cs
new file mode 100644
index 000000000..217025245
--- /dev/null
+++ b/FRBDK/Glue/Glue/Themes/Converters/ScrollThrottleBehavior.cs
@@ -0,0 +1,43 @@
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Input;
+
+namespace FlatRedBall.Glue.Themes.Converters;
+
+public static class ScrollThrottleBehavior
+{
+    public static readonly DependencyProperty IsEnabledProperty =
+        DependencyProperty.RegisterAttached(
+            "IsEnabled",
+            typeof(bool),
+            typeof(ScrollThrottleBehavior),
+            new PropertyMetadata(false, OnIsEnabledChanged));
+
+    public static bool GetIsEnabled(ScrollViewer obj) => (bool)obj.GetValue(IsEnabledProperty);
+    public static void SetIsEnabled(ScrollViewer obj, bool value) => obj.SetValue(IsEnabledProperty, value);
+
+    private static void OnIsEnabledChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
+    {
+        if (d is ScrollViewer scrollViewer
+            )
+        {
+            if ((bool)e.NewValue)
+            {
+                scrollViewer.PreviewMouseWheel += OnMouseWheel;
+            }
+            else
+            {
+                scrollViewer.PreviewMouseWheel -= OnMouseWheel;
+            }
+        }
+    }
+
+    private static void OnMouseWheel(object sender, MouseWheelEventArgs e)
+    {
+        if (sender is ScrollViewer scrollViewer && System.Math.Abs(e.Delta) != 120)
+        {
+            scrollViewer.ScrollToVerticalOffset(scrollViewer.VerticalOffset + ((double)e.Delta /120));
+            e.Handled = true;
+        }
+    }
+}
diff --git a/FRBDK/Glue/Glue/Themes/Frb.Styles.xaml b/FRBDK/Glue/Glue/Themes/Frb.Styles.xaml
index b50ee3e8a..1b7d3efdf 100644
--- a/FRBDK/Glue/Glue/Themes/Frb.Styles.xaml
+++ b/FRBDK/Glue/Glue/Themes/Frb.Styles.xaml
@@ -39,7 +39,9 @@
         <Setter Property="TextOptions.TextRenderingMode" Value="Auto" />
     </Style>
 
-    <Style TargetType="{x:Type ScrollViewer}" BasedOn="{StaticResource MaterialDesignScrollViewer}" />
+  <Style TargetType="{x:Type ScrollViewer}" BasedOn="{StaticResource MaterialDesignScrollViewer}">
+    <Setter Property="converters:ScrollThrottleBehavior.IsEnabled" Value="True" />
+  </Style>
 
     <Style TargetType="{x:Type ScrollBar}" BasedOn="{StaticResource MaterialDesignScrollBar}">
         <Style.Resources>