Support ControlTheme in XAML compiler.

src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/AvaloniaXamlIlCompiler.cs

@@ -48,6 +48,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
 
             InsertBefore<ContentConvertTransformer>(                
                 new AvaloniaXamlIlBindingPathParser(),
+                new AvaloniaXamlIlControlThemeTransformer(),
                 new AvaloniaXamlIlSelectorTransformer(),
                 new AvaloniaXamlIlControlTemplateTargetTypeMetadataTransformer(),
                 new AvaloniaXamlIlPropertyPathTransformer(),

src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/Transformers/AvaloniaXamlIlControlThemeTransformer.cs

@@ -0,0 +1,39 @@
+using System.Linq;
+using XamlX;
+using XamlX.Ast;
+using XamlX.Transform;
+using XamlX.Transform.Transformers;
+using XamlX.TypeSystem;
+
+namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
+{
+    class AvaloniaXamlIlControlThemeTransformer : IXamlAstTransformer
+    {
+        public IXamlAstNode Transform(AstTransformationContext context, IXamlAstNode node)
+        {
+            if (!(node is XamlAstObjectNode on && on.Type.GetClrType().FullName == "Avalonia.Styling.ControlTheme"))
+                return node;
+
+            // Check if we've already transformed this node.
+            if (context.ParentNodes().FirstOrDefault() is AvaloniaXamlIlTargetTypeMetadataNode)
+                return node;
+
+            var targetTypeNode = on.Children.OfType<XamlAstXamlPropertyValueNode>()
+                .FirstOrDefault(p => p.Property.GetClrProperty().Name == "TargetType") ??
+                throw new XamlParseException("ControlTheme must have a TargetType.", node);
+
+            IXamlType targetType;
+
+            if (targetTypeNode.Values[0] is XamlTypeExtensionNode extension)
+                targetType = extension.Value.GetClrType();
+            else if (targetTypeNode.Values[0] is XamlAstTextNode text)
+                targetType = TypeReferenceResolver.ResolveType(context, text.Text, false, text, true).GetClrType();
+            else
+                throw new XamlParseException("Could not determine TargetType for ControlTheme.", targetTypeNode);
+
+            return new AvaloniaXamlIlTargetTypeMetadataNode(on,
+                new XamlAstClrTypeReference(targetTypeNode, targetType, false),
+                AvaloniaXamlIlTargetTypeMetadataNode.ScopeTypes.Style);
+        }
+    }
+}

src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/Transformers/AvaloniaXamlIlSetterTransformer.cs

@@ -1,19 +1,14 @@
-using System;
 using System.Collections.Generic;
 using System.Linq;
-using Avalonia.Data.Core;
-using XamlX;
 using XamlX.Ast;
 using XamlX.Emit;
 using XamlX.IL;
 using XamlX.Transform;
-using XamlX.Transform.Transformers;
 using XamlX.TypeSystem;
 
 namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
 {
     using XamlParseException = XamlX.XamlParseException;
-    using XamlLoadException = XamlX.XamlLoadException;
     class AvaloniaXamlIlSetterTransformer : IXamlAstTransformer
     {
         public IXamlAstNode Transform(AstTransformationContext context, IXamlAstNode node)
@@ -22,21 +17,10 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
                   && on.Type.GetClrType().FullName == "Avalonia.Styling.Setter"))
                 return node;
 
-            var parent = context.ParentNodes().OfType<XamlAstObjectNode>()
-                .FirstOrDefault(p => p.Type.GetClrType().FullName == "Avalonia.Styling.Style");
-            
-            if (parent == null)
-                throw new XamlParseException(
-                    "Avalonia.Styling.Setter is only valid inside Avalonia.Styling.Style", node);
-            var selectorProperty = parent.Children.OfType<XamlAstXamlPropertyValueNode>()
-                .FirstOrDefault(p => p.Property.GetClrProperty().Name == "Selector");
-            if (selectorProperty == null)
-                throw new XamlParseException(
-                    "Can not find parent Style Selector", node);
-            var selector = selectorProperty.Values.FirstOrDefault() as XamlIlSelectorNode;
-            if (selector?.TargetType == null)
-                throw new XamlParseException(
-                    "Can not resolve parent Style Selector type", node);
+            var targetTypeNode = context.ParentNodes()
+                .OfType<AvaloniaXamlIlTargetTypeMetadataNode>()
+                .FirstOrDefault(x => x.ScopeType == AvaloniaXamlIlTargetTypeMetadataNode.ScopeTypes.Style) ??
+                throw new XamlParseException("Can not find parent Style Selector or ControlTemplate TargetType", node);
 
             IXamlType propType = null;
             var property = @on.Children.OfType<XamlAstXamlPropertyValueNode>()
@@ -50,7 +34,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
 
 
                 var avaloniaPropertyNode = XamlIlAvaloniaPropertyHelper.CreateNode(context, propertyName,
-                    new XamlAstClrTypeReference(selector, selector.TargetType, false), property.Values[0]);
+                    new XamlAstClrTypeReference(targetTypeNode, targetTypeNode.TargetType.GetClrType(), false), property.Values[0]);
                 property.Values = new List<IXamlAstValueNode> {avaloniaPropertyNode};
                 propType = avaloniaPropertyNode.AvaloniaPropertyType;
             }
@@ -84,6 +68,55 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
             return node;
         }
 
+        private (IXamlLineInfo, IXamlType) GetTargetType(AstTransformationContext context, IXamlAstNode node)
+        {
+            foreach (var n in context.ParentNodes())
+            {
+                if (n is XamlAstObjectNode parent)
+                {
+                    switch (parent.Type.GetClrType().FullName)
+                    {
+                        case "Avalonia.Styling.Style":
+                            var selectorProperty = parent.Children.OfType<XamlAstXamlPropertyValueNode>()
+                                .FirstOrDefault(p => p.Property.GetClrProperty().Name == "Selector");
+                            if (selectorProperty == null)
+                                throw new XamlParseException("Can not find parent Style Selector.", node);
+                            var selector = selectorProperty.Values.FirstOrDefault() as XamlIlSelectorNode;
+                            if (selector?.TargetType != null)
+                                return (selector, selector.TargetType);
+                            throw new XamlParseException(
+                                "Can not resolve parent Style Selector type", node);
+
+                        case "Avalonia.Styling.ControlTheme":
+                            var targetTypeProperty = parent.Children.OfType<XamlAstXamlPropertyValueNode>()
+                                .FirstOrDefault(p => p.Property.GetClrProperty().Name == "TargetType");
+                            if (targetTypeProperty == null)
+                                throw new XamlParseException("ControlTemplate has no TargetType.", parent);
+                            break;
+                    }
+                }
+            }
+
+            throw new XamlParseException("'Setter' is only valid inside a 'Style' or 'ControlTheme'.", node);
+            //var parent = context.ParentNodes().OfType<XamlAstObjectNode>()
+            //    .FirstOrDefault(p => p.Type.GetClrType().FullName == "Avalonia.Styling.Style" ||
+            //                         p.Type.GetClrType().FullName == "Avalonia.Styling.ControlTheme");
+
+            //if (parent == null)
+            //    throw new XamlParseException(
+            //        "Avalonia.Styling.Setter is only valid inside Avalonia.Styling.Style", node);
+            //var selectorProperty = parent.Children.OfType<XamlAstXamlPropertyValueNode>()
+            //    .FirstOrDefault(p => p.Property.GetClrProperty().Name == "Selector" ||
+            //                         p.Property.GetClrProperty().Name == "TargetType");
+            //if (selectorProperty == null)
+            //    throw new XamlParseException(
+            //        "Can not find parent Style Selector or ControlTemplate TargetType", node);
+            //var selector = selectorProperty.Values.FirstOrDefault() as XamlIlSelectorNode;
+            //if (selector?.TargetType == null)
+            //    throw new XamlParseException(
+            //        "Can not resolve parent Style Selector type", node);
+        }
+
         class SetterValueProperty : XamlAstClrProperty
         {
             public SetterValueProperty(IXamlLineInfo line, IXamlType setterType, IXamlType targetType,

tests/Avalonia.Markup.Xaml.UnitTests/Xaml/ControlThemeTests.cs

@@ -0,0 +1,53 @@
+using Avalonia.Controls;
+using Avalonia.Media;
+using Avalonia.UnitTests;
+using Avalonia.VisualTree;
+using Xunit;
+
+namespace Avalonia.Markup.Xaml.UnitTests.Xaml
+{
+    public class ControlThemeTests : XamlTestBase
+    {
+        [Fact]
+        public void ControlTheme_Can_Be_StaticResource()
+        {
+            using (UnitTestApplication.Start(TestServices.StyledWindow))
+            {
+                var xaml = $@"
+<Window xmlns='https://github.com/avaloniaui'
+        xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'
+        xmlns:u='using:Avalonia.Markup.Xaml.UnitTests.Xaml'>
+    <Window.Resources>
+        {ControlThemeXaml}
+    </Window.Resources>
+
+    <u:TestTemplatedControl Theme='{{StaticResource MyTheme}}'/>
+</Window>";
+
+                var window = (Window)AvaloniaRuntimeXamlLoader.Load(xaml);
+                var button = Assert.IsType<TestTemplatedControl>(window.Content);
+
+                window.LayoutManager.ExecuteInitialLayoutPass();
+
+                Assert.NotNull(button.Template);
+
+                var child = Assert.Single(button.GetVisualChildren());
+                var border = Assert.IsType<Border>(child);
+
+                Assert.Equal(Brushes.Red, border.Background);
+            }
+        }
+
+        private const string ControlThemeXaml = @"
+<ControlTheme x:Key='MyTheme' TargetType='u:TestTemplatedControl'>
+    <Setter Property='Template'>
+        <ControlTemplate>
+            <Border/>
+        </ControlTemplate>
+    </Setter>
+    <Style Selector='^ /template/ Border'>
+        <Setter Property='Background' Value='Red'/>
+    </Style>
+</ControlTheme>";
+    }
+}

tests/Avalonia.Markup.Xaml.UnitTests/Xaml/TestTemplatedControl.cs

@@ -0,0 +1,8 @@
+using Avalonia.Controls.Primitives;
+
+namespace Avalonia.Markup.Xaml.UnitTests.Xaml
+{
+    public class TestTemplatedControl : TemplatedControl
+    {
+    }
+}