Fix for Bug 2761 (AppThemeResource not finding keys)

src/CommunityToolkit.Maui.UnitTests/Extensions/AppThemeResourceExtensionTests.cs

@@ -0,0 +1,29 @@
+using CommunityToolkit.Maui.UnitTests.Mocks;
+using CommunityToolkit.Maui.UnitTests.Resources.Styles;
+using Xunit;
+
+namespace CommunityToolkit.Maui.UnitTests.Extensions;
+
+public class AppThemeResourceExtensionTests : BaseViewTest
+{
+	[Fact]
+	public async Task SetPropertyViaAppThemeResource()
+	{
+		// Arrange
+		MockApplication application = (MockApplication)ServiceProvider.GetRequiredService<IApplication>();
+		bool foundResource;
+
+		// Act
+		try
+		{
+			application.Resources.MergedDictionaries.Add(new AppThemeResourceDictionary());
+			foundResource = true;
+		}
+		catch (Exception)
+		{
+			foundResource = false;
+		}
+		// Assert
+		Assert.True(foundResource, "Failed to load key from AppThemeResourceDictionary. Bug 2761.");
+	}
+}

src/CommunityToolkit.Maui.UnitTests/Resources/Styles/AppThemeResourceDictionary.xaml

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ResourceDictionary 
+    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+    xmlns:tk="http://schemas.microsoft.com/dotnet/2022/maui/toolkit"
+    x:Class="CommunityToolkit.Maui.UnitTests.Resources.Styles.AppThemeResourceDictionary">
+
+    <tk:AppThemeColor x:Key="TextColor" Light="Black"  Dark="White" />
+    <tk:AppThemeColor x:Key="TextBackgroundColor" Light="White"  Dark="Black" />
+
+    <Style TargetType="Entry">
+        <Setter Property="TextColor" Value="{tk:AppThemeResource TextColor}" />
+    </Style>
+
+</ResourceDictionary>

src/CommunityToolkit.Maui.UnitTests/Resources/Styles/AppThemeResourceDictionary.xaml.cs

@@ -0,0 +1,9 @@
+namespace CommunityToolkit.Maui.UnitTests.Resources.Styles;
+
+public partial class AppThemeResourceDictionary : ResourceDictionary
+{
+	public AppThemeResourceDictionary()
+	{
+		InitializeComponent();
+	}
+}

src/CommunityToolkit.Maui/Extensions/AppThemeResourceExtension.shared.cs

@@ -48,22 +48,32 @@ public BindingBase ProvideValue(IServiceProvider serviceProvider)
 			}
 		}
 
-		// Fallback to root object ResourceDictionary (e.g. page-level resources)
+		// Fallback to root object ResourceDictionary (e.g. page-level or application-level resources)
 		var rootProvider = serviceProvider.GetService(typeof(IRootObjectProvider)) as IRootObjectProvider;
 		var root = rootProvider?.RootObject;
-		if (root is IResourcesProvider { IsResourcesCreated: true } rootResources
-			&& rootResources.Resources.TryGetValue(Key, out resource))
+
+		switch (root)
 		{
-			switch (resource)
-			{
-				case AppThemeColor rootColor:
-					return rootColor.GetBinding();
-				case AppThemeObject rootTheme:
-					return rootTheme.GetBinding();
-				default:
-					var info = (serviceProvider.GetService(typeof(IXmlLineInfoProvider)) as IXmlLineInfoProvider)?.XmlLineInfo;
-					throw new XamlParseException($"Resource found for key {Key} is not a valid AppTheme resource.", info);
-			}
+			case IResourcesProvider { IsResourcesCreated: true } rootResources1 when rootResources1.Resources.TryGetValue(Key, out resource):
+				// page level?
+				switch (resource)
+				{
+					case AppThemeColor rootColor:
+						return rootColor.GetBinding();
+					case AppThemeObject rootTheme:
+						return rootTheme.GetBinding();
+				}
+				break;
+			case ResourceDictionary rootDictionary1 when rootDictionary1.TryGetValue(Key, out resource):
+				// application level?
+				switch (resource)
+				{
+					case AppThemeColor rootColor:
+						return rootColor.GetBinding();
+					case AppThemeObject rootTheme:
+						return rootTheme.GetBinding();
+				}
+				break;
 		}
 
 		if (Application.Current?.Resources.TryGetValueAndSource(Key, out resource, out _) is true)