fix: Convert resources to target property type in generated code

Author: Youssef1313

src/SourceGenerators/Uno.UI.SourceGenerators/XamlGenerator/XamlFileGenerator.cs

@@ -4218,8 +4218,6 @@ private string GetCastString(INamedTypeSymbol targetProperty, XamlObjectDefiniti
 			}
 		}
 
-		private int _staticResourceResolverOutputIndex = 0;
-
 		/// <summary>
 		/// Returns code for simple initialization-time retrieval for StaticResource/ThemeResource markup.
 		/// </summary>
@@ -4228,21 +4226,9 @@ private string GetSimpleStaticResourceRetrieval(INamedTypeSymbol? targetProperty
 			targetPropertyType = targetPropertyType ?? _objectSymbol;
 
 			var targetPropertyFQT = targetPropertyType.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat);
-			var propertyOutputVar = $"staticResourceResolverOutputIndex{_staticResourceResolverOutputIndex++}";
-
-			var conversion = targetPropertyType.IsValueType
-				? $"(({targetPropertyFQT}){propertyOutputVar})"
-				: $"(({propertyOutputVar} as {targetPropertyFQT}) ?? default({targetPropertyFQT}))";
-
 
-			var staticRetrieval = $"(" +
-				$"global::Uno.UI.ResourceResolverSingleton.Instance.ResolveResourceStatic(" +
-				$"\"{keyStr}\", " +
-				$"out var {propertyOutputVar}, " +
-				$"context: {ParseContextPropertyAccess}) " +
-				$"? {conversion}" +
-				$" : default({targetPropertyFQT})" +
-				$")";
+			var staticRetrieval = $"global::Uno.UI.ResourceResolverSingleton.Instance.ResolveResourceStatic<{targetPropertyFQT}>(" +
+				$"\"{keyStr}\", context: {ParseContextPropertyAccess})";
 			TryAnnotateWithGeneratorSource(ref staticRetrieval);
 			return staticRetrieval;
 		}

src/Uno.UI.RuntimeTests/Tests/Uno_UI/Given_ResourceResolver.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Windows.UI.Xaml;
+using static Private.Infrastructure.TestServices;
+
+namespace Uno.UI.RuntimeTests.Tests.Uno_UI
+{
+	public class MyCustomClass
+	{
+		public Duration Duration { get; set; }
+	}
+
+	[TestClass]
+	public class Given_ResourceResolver
+	{
+		[TestMethod]
+		[RunsOnUIThread]
+		public void When_Resolving_String_Resources_Should_Produce_Target_Type()
+		{
+			var SUT = new Resolve_String_Resources();
+			WindowHelper.WindowContent = SUT;
+			var expected = new Duration(TimeSpan.Parse("00:00:00.250"));
+
+			Assert.AreEqual(expected, SUT.ReferencingStringDurationFromDP.Duration);
+			Assert.AreEqual(expected, SUT.ReferenceStringDurationFromProperty.Duration);
+		}
+	}
+}

src/Uno.UI.RuntimeTests/Tests/Uno_UI/Resolve_String_Resources.xaml

@@ -0,0 +1,20 @@
+<Page
+    x:Class="Uno.UI.RuntimeTests.Tests.Uno_UI.Resolve_String_Resources"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:local="using:Uno.UI.RuntimeTests.Tests.Uno_UI"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    mc:Ignorable="d"
+    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
+	<Page.Resources>
+		<x:String x:Key="StringDuration">00:00:00.250</x:String>
+
+		<!-- Duration is a dependency property. -->
+		<Storyboard x:Name="ReferencingStringDurationFromDP" Duration="{StaticResource StringDuration}" x:FieldModifier="public" />
+		<local:MyCustomClass x:Name="ReferenceStringDurationFromProperty" Duration="{StaticResource StringDuration}" x:FieldModifier="public" />
+	</Page.Resources>
+    <Grid>
+
+    </Grid>
+</Page>

src/Uno.UI.RuntimeTests/Tests/Uno_UI/Resolve_String_Resources.xaml.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Runtime.InteropServices.WindowsRuntime;
+using Windows.Foundation;
+using Windows.Foundation.Collections;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Controls.Primitives;
+using Windows.UI.Xaml.Data;
+using Windows.UI.Xaml.Input;
+using Windows.UI.Xaml.Media;
+using Windows.UI.Xaml.Navigation;
+
+// The Blank Page item template is documented at https://go.microsoft.com/fwlink/?LinkId=234238
+
+namespace Uno.UI.RuntimeTests.Tests.Uno_UI
+{
+	/// <summary>
+	/// An empty page that can be used on its own or navigated to within a Frame.
+	/// </summary>
+	public sealed partial class Resolve_String_Resources : Page
+	{
+		public Resolve_String_Resources()
+		{
+			this.InitializeComponent();
+		}
+	}
+}

src/Uno.UI/UI/Xaml/ResourceResolver.cs

@@ -63,9 +63,22 @@ static ResourceResolver()
 		[EditorBrowsable(EditorBrowsableState.Never)]
 		public static T ResolveResourceStatic<T>(object key, object context = null)
 		{
-			if (TryStaticRetrieval(new SpecializedResourceDictionary.ResourceKey(key), context, out var value) && value is T tValue)
+			if (TryStaticRetrieval(new SpecializedResourceDictionary.ResourceKey(key), context, out var value))
 			{
-				return tValue;
+				if (value is T tValue)
+				{
+					return tValue;
+				}
+				else
+				{
+					var convertedValue = BindingPropertyHelper.Convert(() => typeof(T), value);
+					if (convertedValue is null && _log.IsEnabled(LogLevel.Warning))
+					{
+						_log.LogWarning($"Unable to convert value '{value}' of type '{value.GetType()}' to type '{typeof(T)}'");
+					}
+
+					return (T)convertedValue;
+				}
 			}
 
 			return default(T);

src/Uno.UI/UI/Xaml/ResourceResolverSingleton.cs

@@ -30,6 +30,9 @@ public sealed class ResourceResolverSingleton
 		[EditorBrowsable(EditorBrowsableState.Never)]
 		public bool ResolveResourceStatic(object key, out object value, object context) => ResourceResolver.ResolveResourceStatic(key, out value, context);
 
+		[EditorBrowsable(EditorBrowsableState.Never)]
+		public T ResolveResourceStatic<T>(object key, object context) => ResourceResolver.ResolveResourceStatic<T>(key, context);
+
 		[EditorBrowsable(EditorBrowsableState.Never)]
 		public void ApplyResource(DependencyObject owner, DependencyProperty property, object resourceKey, bool isThemeResourceExtension, object context) => ResourceResolver.ApplyResource(owner, property, resourceKey, isThemeResourceExtension, context);