From aaa9036e8948030ccb1892c638c1eaba8721d951 Mon Sep 17 00:00:00 2001
From: Sergio Pedri <sergio0694@live.com>
Date: Mon, 13 Sep 2021 20:28:42 +0200
Subject: [PATCH] Added DispatcherQueue dispatching for high contrast theme
 change

---
 Microsoft.Toolkit.Uwp.UI/Helpers/ThemeListener.cs   | 13 ++++++++-----
 .../XamlIslandsTest_ThemeListener_Threading.cs      |  4 ++--
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/Microsoft.Toolkit.Uwp.UI/Helpers/ThemeListener.cs b/Microsoft.Toolkit.Uwp.UI/Helpers/ThemeListener.cs
index 4d34da111b6..9db0cecac32 100644
--- a/Microsoft.Toolkit.Uwp.UI/Helpers/ThemeListener.cs
+++ b/Microsoft.Toolkit.Uwp.UI/Helpers/ThemeListener.cs
@@ -79,23 +79,26 @@ public ThemeListener(DispatcherQueue dispatcherQueue = null)
             }
         }
 
-        private void Accessible_HighContrastChanged(AccessibilitySettings sender, object args)
+        private async void Accessible_HighContrastChanged(AccessibilitySettings sender, object args)
         {
 #if DEBUG
             System.Diagnostics.Debug.WriteLine("HighContrast Changed");
 #endif
 
-            UpdateProperties();
+            await OnThemePropertyChangedAsync();
         }
 
         // Note: This can get called multiple times during HighContrast switch, do we care?
         private async void Settings_ColorValuesChanged(UISettings sender, object args)
         {
-            await OnColorValuesChanged();
+            await OnThemePropertyChangedAsync();
         }
 
-        // Internal abstraction is used by the Unit Tests
-        internal Task OnColorValuesChanged()
+        /// <summary>
+        /// Dispatches an update for the public properties and the firing of <see cref="ThemeChanged"/> on <see cref="DispatcherQueue"/>.
+        /// </summary>
+        /// <returns>A <see cref="Task"/> that indicates when the dispatching has completed.</returns>
+        internal Task OnThemePropertyChangedAsync()
         {
             // Getting called off thread, so we need to dispatch to request value.
             return DispatcherQueue.EnqueueAsync(
diff --git a/UnitTests/UnitTests.XamlIslands.UWPApp/XamlIslandsTest_ThemeListener_Threading.cs b/UnitTests/UnitTests.XamlIslands.UWPApp/XamlIslandsTest_ThemeListener_Threading.cs
index 61e73850b40..86ab15413fd 100644
--- a/UnitTests/UnitTests.XamlIslands.UWPApp/XamlIslandsTest_ThemeListener_Threading.cs
+++ b/UnitTests/UnitTests.XamlIslands.UWPApp/XamlIslandsTest_ThemeListener_Threading.cs
@@ -39,7 +39,7 @@ public Task Init()
         [TestMethod]
         public async Task ThemeListenerDispatcherTestAsync()
         {
-            await _themeListener.OnColorValuesChanged();
+            await _themeListener.OnThemePropertyChangedAsync();
 
             await _taskCompletionSource.Task;
         }
@@ -49,7 +49,7 @@ public async Task ThemeListenerDispatcherTestFromOtherThreadAsync()
         {
             await Task.Run(async () =>
             {
-                await _themeListener.OnColorValuesChanged();
+                await _themeListener.OnThemePropertyChangedAsync();
             });
             await _taskCompletionSource.Task;
         }