Add support for changing the true color for a toggle switch

FormsCommunityToolkit.Effects/FormsCommunityToolkit.Effects.UWP/Effects/ChangeColorSwitchEffect.cs

@@ -0,0 +1,88 @@
+using Windows.UI.Xaml.Controls;
+using FormsCommunityToolkit.Effects.UWP.Effects;
+using Xamarin.Forms;
+using Xamarin.Forms.Internals;
+using Xamarin.Forms.Platform.UWP;
+using Windows.UI.Xaml.Media;
+using System;
+using Windows.UI.Xaml;
+using System.Linq;
+using Windows.UI.Xaml.Media.Animation;
+
+[assembly: ExportEffect(typeof(ChangeColorSwitchEffect), nameof(ChangeColorSwitchEffect))]
+
+namespace FormsCommunityToolkit.Effects.UWP.Effects
+{
+    [Preserve]
+    public class ChangeColorSwitchEffect : PlatformEffect
+    {
+        private Windows.UI.Color _trueColor;
+        private Windows.UI.Color _falseColor;
+
+        protected override void OnAttached()
+        {
+            var color = (Color)Element.GetValue(ChangeColorEffect.TrueColorProperty);
+            _trueColor = ConvertColor(color);
+
+            // currently not supported
+            color = (Color)Element.GetValue(ChangeColorEffect.FalseColorProperty);
+            _falseColor = ConvertColor(color);
+
+            var toggleSwitch = Control as ToggleSwitch;
+            if (toggleSwitch != null)
+            {
+                toggleSwitch.Loaded -= OnSwitchLoaded;
+                toggleSwitch.Loaded += OnSwitchLoaded;
+            }
+        }
+
+        protected override void OnDetached()
+        {
+            var toggleSwitch = Control as ToggleSwitch;
+            if (toggleSwitch != null)
+            {
+                toggleSwitch.Loaded -= OnSwitchLoaded;
+            }
+        }
+
+        private void OnSwitchLoaded(object sender, RoutedEventArgs e)
+        {
+            var toggleSwitch = Control as ToggleSwitch;
+            var grid = toggleSwitch.GetChildOfType<Windows.UI.Xaml.Controls.Grid>();
+            var groups = VisualStateManager.GetVisualStateGroups(grid);
+            foreach (var group in groups)
+            {
+                if (group.Name != "CommonStates") continue;
+
+                foreach (var state in group.States)
+                {
+                    if (state.Name != "PointerOver") continue;
+
+                    foreach (var timeline in state.Storyboard.Children.OfType<ObjectAnimationUsingKeyFrames>())
+                    {
+                        var property = Storyboard.GetTargetProperty(timeline);
+                        var target = Storyboard.GetTargetName(timeline);
+                        if ((target == "SwitchKnobBounds") && (property == "Fill"))
+                        {
+                            var frame = timeline.KeyFrames.First();
+                            frame.Value = new SolidColorBrush(_trueColor) { Opacity = .7 };
+                            break;
+                        }
+                    }
+                }
+            }
+
+            var rect = toggleSwitch.GetChildByName("SwitchKnobBounds") as Windows.UI.Xaml.Shapes.Rectangle;
+            if (rect != null)
+            {
+                rect.Fill = new SolidColorBrush(_trueColor);
+            }
+            toggleSwitch.Loaded -= OnSwitchLoaded;
+        }
+
+        private Windows.UI.Color ConvertColor(Xamarin.Forms.Color color)
+        {
+            return Windows.UI.Color.FromArgb((byte)(color.A * 255), (byte)(color.R * 255), (byte)(color.G * 255), (byte)(color.B * 255));
+        }
+    }
+}

FormsCommunityToolkit.Effects/FormsCommunityToolkit.Effects.UWP/FormsCommunityToolkit.Effects.UWP.csproj

@@ -107,11 +107,13 @@
     <None Include="project.json" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Effects\ChangeColorSwitchEffect.cs" />
     <Compile Include="Effects\CapitalizeKeyboardEffect.cs" />
     <Compile Include="Effects\MultiLineLabelEffect.cs" />
     <Compile Include="Effects\RemoveBorderEffect.cs" />
     <Compile Include="Effects\ViewBlurEffect.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="VisualTreeExtensions.cs" />
     <EmbeddedResource Include="Properties\Organon.XForms.Effects.UWP.rd.xml" />
   </ItemGroup>
   <ItemGroup>

FormsCommunityToolkit.Effects/FormsCommunityToolkit.Effects.UWP/VisualTreeExtensions.cs

@@ -0,0 +1,41 @@
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Media;
+
+namespace FormsCommunityToolkit.Effects.UWP
+{
+    static class VisualTreeExtensions
+    {
+        public static T GetChildOfType<T>(this DependencyObject obj) where T: DependencyObject
+        {
+            if (obj == null) return null;
+
+            for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
+            {
+                var child = VisualTreeHelper.GetChild(obj, i);
+
+                var result = (child as T) ?? GetChildOfType<T>(child);
+                if (result != null) return result;
+            }
+            return null;
+        }
+
+        public static FrameworkElement GetChildByName(this FrameworkElement obj, string name)
+        {
+            if (obj == null) return null;
+
+            for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
+            {
+                var child = VisualTreeHelper.GetChild(obj, i) as FrameworkElement;
+                if (child == null) continue;
+
+                if(child.Name == name)
+                {
+                    return child;
+                }
+                var result = GetChildByName(child, name);
+                if (result != null) return result;
+            }
+            return null;
+        }
+    }
+}