Merge pull request #5096 from AvaloniaUI/fixes/dynamicresource-in-application

Fix DynamicResource lookup in Application.

src/Avalonia.Styling/ApiCompatBaseline.txt

@@ -0,0 +1,3 @@
+Compat issues with assembly Avalonia.Styling:
+MembersMustExist : Member 'public System.IObservable<System.Object> Avalonia.Controls.ResourceNodeExtensions.GetResourceObservable(Avalonia.IStyledElement, System.Object, System.Func<System.Object, System.Object>)' does not exist in the implementation but it does exist in the contract.
+Total Issues: 1

src/Avalonia.Styling/Controls/ResourceNodeExtensions.cs

@@ -60,7 +60,7 @@ namespace Avalonia.Controls
         }
 
         public static IObservable<object?> GetResourceObservable(
-            this IStyledElement control,
+            this IResourceHost control,
             object key,
             Func<object?, object?>? converter = null)
         {
@@ -83,11 +83,11 @@ namespace Avalonia.Controls
 
         private class ResourceObservable : LightweightObservableBase<object?>
         {
-            private readonly IStyledElement _target;
+            private readonly IResourceHost _target;
             private readonly object _key;
             private readonly Func<object?, object?>? _converter;
 
-            public ResourceObservable(IStyledElement target, object key, Func<object?, object?>? converter)
+            public ResourceObservable(IResourceHost target, object key, Func<object?, object?>? converter)
             {
                 _target = target;
                 _key = key;

src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/DynamicResourceExtension.cs

@@ -10,8 +10,7 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions
 {
     public class DynamicResourceExtension : IBinding
     {
-        private IStyledElement? _anchor;
-        private IResourceProvider? _resourceProvider;
+        private object? _anchor;
 
         public DynamicResourceExtension()
         {
@@ -30,12 +29,9 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions
 
             if (!(provideTarget.TargetObject is IStyledElement))
             {
-                _anchor = serviceProvider.GetFirstParent<IStyledElement>();
-
-                if (_anchor is null)
-                {
-                    _resourceProvider = serviceProvider.GetFirstParent<IResourceProvider>();
-                }
+                _anchor = serviceProvider.GetFirstParent<IStyledElement>() ??
+                    serviceProvider.GetFirstParent<IResourceProvider>() ??
+                    (object?)serviceProvider.GetFirstParent<IResourceHost>();
             }
 
             return this;
@@ -52,16 +48,16 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions
                 return null;
             }
 
-            var control = target as IStyledElement ?? _anchor as IStyledElement;
+            var control = target as IResourceHost ?? _anchor as IResourceHost;
 
             if (control != null)
             {
                 var source = control.GetResourceObservable(ResourceKey, GetConverter(targetProperty));
                 return InstancedBinding.OneWay(source);
             }
-            else if (_resourceProvider is object)
+            else if (_anchor is IResourceProvider resourceProvider)
             {
-                var source = _resourceProvider.GetResourceObservable(ResourceKey, GetConverter(targetProperty));
+                var source = resourceProvider.GetResourceObservable(ResourceKey, GetConverter(targetProperty));
                 return InstancedBinding.OneWay(source);
             }
 

tests/Avalonia.Markup.Xaml.UnitTests/MarkupExtensions/DynamicResourceExtensionTests.cs

@@ -345,6 +345,23 @@ namespace Avalonia.Markup.Xaml.UnitTests.MarkupExtensions
             Assert.Equal(0xff506070, brush.Color.ToUint32());
         }
 
+        [Fact]
+        public void DynamicResource_Can_Be_Assigned_To_Resource_Property_In_Application()
+        {
+            var xaml = @"
+<Application xmlns='https://github.com/avaloniaui'
+             xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'>
+    <Application.Resources>
+        <Color x:Key='color'>#ff506070</Color>
+        <SolidColorBrush x:Key='brush' Color='{DynamicResource color}'/>
+    </Application.Resources>
+</Application>";
+
+            var application = (Application)AvaloniaRuntimeXamlLoader.Load(xaml);
+            var brush = (SolidColorBrush)application.Resources["brush"];
+
+            Assert.Equal(0xff506070, brush.Color.ToUint32());
+        }
 
         [Fact]
         public void DynamicResource_Can_Be_Assigned_To_ItemTemplate_Property()