feat(xamlreader): Support CustomResource

src/Uno.UI.Tests/Uno.UI.Tests.csproj

@@ -104,6 +104,7 @@
 		<Page Include="HotReload\Windows_UI_Xaml\**\*.xaml" />
 		<Page Include="App\**\*.xaml" />
 		<None Remove="Lottie\animation.json" />
+		<None Remove="Windows_UI_Xaml_Markup\XamlReaderTests\When_CustomResource.xamltest" />
 		<Page Include="..\SamplesApp\UITests.Shared\Windows_UI_Xaml\Resources\Test_Dictionary_Linked.xaml" Link="App/Linked/Test_Dictionary_Linked.xaml" />
 	</ItemGroup>
 	<ItemGroup>

src/Uno.UI.Tests/Windows_UI_Xaml_Markup/XamlReaderTests/Given_XamlReader.cs

@@ -301,6 +301,43 @@ public void When_ThemeResource_Lazy()
 			Assert.AreEqual(44.0, panel.Height);
 		}
 
+		[TestMethod]
+		public void When_CustomResource()
+		{
+			var savedState = Windows.UI.Xaml.Resources.CustomXamlResourceLoader.Current;
+			try
+			{
+				var loader = new TestCustomXamlResourceLoader();
+				var resourceValue = "This is a CustomResource.";
+				var resourceKey = "myCustomResource";
+				loader.TestCustomResources[resourceKey] = resourceValue;
+				Windows.UI.Xaml.Resources.CustomXamlResourceLoader.Current = loader;
+
+				var s = GetContent(nameof(When_CustomResource));
+				var r = Windows.UI.Xaml.Markup.XamlReader.Load(s) as Page;
+
+				Assert.IsNotNull(r);
+
+				var tb = r.Content as TextBlock;
+
+				Assert.IsNotNull(tb);
+				Assert.AreEqual(resourceValue, tb.Text);
+
+				var objectType = tb.GetType().FullName;
+				var propertyName = nameof(tb.Text);
+				var propertyType = tb.Text.GetType().FullName;
+
+				Assert.AreEqual(loader.LastResourceId, resourceKey);
+				Assert.AreEqual(loader.LastObjectType, objectType);
+				Assert.AreEqual(loader.LastPropertyName, propertyName);
+				Assert.AreEqual(loader.LastPropertyType, propertyType);
+			}
+			finally
+			{
+				Windows.UI.Xaml.Resources.CustomXamlResourceLoader.Current = savedState;
+			}
+		}
+
 		[TestMethod]
 		public void When_TextBlock_Basic()
 		{

src/Uno.UI.Tests/Windows_UI_Xaml_Markup/XamlReaderTests/TestCustomResourceLoader.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Windows.UI.Xaml.Resources;
+
+namespace Uno.UI.Tests.Windows_UI_Xaml_Markup.XamlReaderTests
+{
+	internal class TestCustomXamlResourceLoader : CustomXamlResourceLoader
+	{
+		internal Dictionary<string, object> TestCustomResources { get; set; } = new Dictionary<string, object>();
+
+        public string LastResourceId { get; set; }
+        public string LastObjectType { get; set; }
+        public string LastPropertyName { get; set; }
+        public string LastPropertyType { get; set; }
+
+		protected override object GetResource(string resourceId, string objectType, string propertyName, string propertyType)
+		{
+		    LastResourceId = resourceId;
+		    LastObjectType = objectType;
+		    LastPropertyName = propertyName;
+		    LastPropertyType = propertyType;
+			if (TestCustomResources.ContainsKey(resourceId) && TestCustomResources[resourceId].GetType().FullName == propertyType)
+			{
+				return TestCustomResources[resourceId];
+			}
+			return null;
+		}
+	}
+}

src/Uno.UI.Tests/Windows_UI_Xaml_Markup/XamlReaderTests/When_CustomResource.xamltest

@@ -0,0 +1,9 @@
+<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+      xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+			Name="rootPage"
+      mc:Ignorable="d">
+
+	<TextBlock Text="{CustomResource myCustomResource}" />
+</Page>

src/Uno.UI/UI/Xaml/Markup/Reader/XamlObjectBuilder.cs

@@ -17,6 +17,7 @@
 using Windows.UI.Text;
 using Windows.Foundation.Metadata;
 using Color = Windows.UI.Color;
+using Windows.UI.Xaml.Resources;
 
 #if XAMARIN_ANDROID
 using _View = Android.Views.View;
@@ -711,7 +712,7 @@ private void ProcessMemberMarkupExtension(object instance, object? rootInstance,
 			{
 				ProcessBindingMarkupNode(instance, rootInstance, member);
 			}
-			else if (IsStaticResourceMarkupNode(member) || IsThemeResourceMarkupNode(member))
+			else if (IsStaticResourceMarkupNode(member) || IsThemeResourceMarkupNode(member) || IsCustomResourceMarkupNode(member))
 			{
 				ProcessStaticResourceMarkupNode(instance, member, propertyInfo);
 			}
@@ -730,20 +731,35 @@ private void ProcessStaticResourceMarkupNode(object instance, XamlMemberDefiniti
 					&& dependencyProperty != null
 					&& instance is DependencyObject dependencyObject)
 				{
-					ResourceResolver.ApplyResource(
-						dependencyObject,
-						dependencyProperty,
-						keyName,
-						isThemeResourceExtension: IsThemeResourceMarkupNode(member),
-						isHotReloadSupported: true);
-
-					if (instance is FrameworkElement fe)
+					if (IsCustomResourceMarkupNode(member))
 					{
-						fe.Loading += delegate
+						var objectType = dependencyObject.GetType().FullName;
+						var propertyName = dependencyProperty.Name;
+						var propertyType = dependencyProperty.Type.FullName;
+						var resource = CustomXamlResourceLoader.Current?.GetResourceInternal(keyName, objectType, propertyName, propertyType);
+						if (resource != null && resource.GetType() == dependencyProperty.Type)
 						{
-							fe.UpdateResourceBindings();
-						};
+							dependencyObject.SetValue(dependencyProperty, resource);
+						}
 					}
+					else
+					{
+						ResourceResolver.ApplyResource(
+							dependencyObject,
+							dependencyProperty,
+							keyName,
+							isThemeResourceExtension: IsThemeResourceMarkupNode(member),
+							isHotReloadSupported: true);
+
+						if (instance is FrameworkElement fe)
+						{
+							fe.Loading += delegate
+							{
+								fe.UpdateResourceBindings();
+							};
+						}
+					}
+
 				}
 				else if (propertyInfo != null)
 				{
@@ -792,6 +808,9 @@ private bool IsStaticResourceMarkupNode(XamlMemberDefinition member)
 		private bool IsThemeResourceMarkupNode(XamlMemberDefinition member)
 			=> member.Objects.Any(o => o.Type.Name == "ThemeResource");
 
+		private bool IsCustomResourceMarkupNode(XamlMemberDefinition member)
+			=> member.Objects.Any(o => o.Type.Name == "CustomResource");
+
 		private bool IsResourcesProperty(PropertyInfo propertyInfo)
 			=> propertyInfo.Name == "Resources" && propertyInfo.PropertyType == typeof(ResourceDictionary);
 
@@ -996,6 +1015,7 @@ private static bool IsMarkupExtension(XamlMemberDefinition member)
 					|| m.Type.Name == "Bind"
 					|| m.Type.Name == "StaticResource"
 					|| m.Type.Name == "ThemeResource"
+					|| m.Type.Name == "CustomResource"
 					|| m.Type.Name == "TemplateBinding"
 				)
 				.Any();