Optimizing resource related code.

src/Avalonia.Base/Controls/ResourceNodeExtensions.cs

@@ -40,19 +40,16 @@ namespace Avalonia.Controls
             control = control ?? throw new ArgumentNullException(nameof(control));
             key = key ?? throw new ArgumentNullException(nameof(key));
 
-            IResourceHost? current = control;
+            IResourceNode? current = control;
 
             while (current != null)
             {
-                if (current is IResourceHost host)
+                if (current.TryGetResource(key, out value))
                 {
-                    if (host.TryGetResource(key, out value))
-                    {
-                        return true;
-                    }
+                    return true;
                 }
 
-                current = (current as IStyledElement)?.StylingParent as IResourceHost;
+                current = (current as IStyledElement)?.StylingParent as IResourceNode;
             }
 
             value = null;

src/Avalonia.Base/Styling/IStyle.cs

@@ -8,7 +8,7 @@ namespace Avalonia.Styling
     /// <summary>
     /// Defines the interface for styles.
     /// </summary>
-    public interface IStyle
+    public interface IStyle : IResourceNode
     {
         /// <summary>
         /// Gets a collection of child styles.

src/Avalonia.Base/Styling/Styles.cs

@@ -160,7 +160,7 @@ namespace Avalonia.Styling
 
             for (var i = Count - 1; i >= 0; --i)
             {
-                if (this[i] is IResourceProvider p && p.TryGetResource(key, out value))
+                if (this[i].TryGetResource(key, out value))
                 {
                     return true;
                 }

src/Avalonia.Themes.Default/Controls/DataValidationErrors.xaml

@@ -1,9 +1,13 @@
 <Style xmlns="https://github.com/avaloniaui" 
-       Selector="DataValidationErrors">
+       xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+       Selector="DataValidationErrors"
+       x:CompileBindings="True"
+       x:DataType="DataValidationErrors">
   <Setter Property="Template">
     <ControlTemplate>
       <DockPanel LastChildFill="True">
-        <ContentControl DockPanel.Dock="Right"
+        <ContentControl x:DataType="DataValidationErrors"
+                        DockPanel.Dock="Right"
                         ContentTemplate="{TemplateBinding ErrorTemplate}"
                         DataContext="{TemplateBinding Owner}"
                         Content="{Binding (DataValidationErrors.Errors)}"
@@ -30,7 +34,7 @@
           </Style>
         </Canvas.Styles>
         <ToolTip.Tip>
-          <ItemsControl Items="{Binding}"/>
+          <ItemsControl x:DataType="DataValidationErrors" Items="{Binding}"/>
         </ToolTip.Tip>
         <Path Data="M14,7 A7,7 0 0,0 0,7 M0,7 A7,7 0 1,0 14,7 M7,3l0,5 M7,9l0,2" Stroke="{DynamicResource ErrorBrush}" StrokeThickness="2"/>
       </Canvas>

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

@@ -39,17 +39,11 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions
                 targetType = setter.Property.PropertyType;
             }
 
-            // Look upwards though the ambient context for IResourceHosts and IResourceProviders
+            // Look upwards though the ambient context for IResourceNodes
             // which might be able to give us the resource.
-            foreach (var e in stack.Parents)
+            foreach (var parent in stack.Parents)
             {
-                object value;
-
-                if (e is IResourceHost host && host.TryGetResource(ResourceKey, out value))
-                {
-                    return ColorToBrushConverter.Convert(value, targetType);
-                }
-                else if (e is IResourceProvider provider && provider.TryGetResource(ResourceKey, out value))
+                if (parent is IResourceNode node && node.TryGetResource(ResourceKey, out var value))
                 {
                     return ColorToBrushConverter.Convert(value, targetType);
                 }
@@ -58,7 +52,10 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions
             if (provideTarget.TargetObject is IControl target &&
                 provideTarget.TargetProperty is PropertyInfo property)
             {
-                DelayedBinding.Add(target, property, x => GetValue(x, targetType));
+                var localTargetType = targetType;
+                var localInstance = this;
+                
+                DelayedBinding.Add(target, property, x => localInstance.GetValue(x, localTargetType));
                 return AvaloniaProperty.UnsetValue;
             }
 

src/Markup/Avalonia.Markup.Xaml/Styling/StyleInclude.cs

@@ -60,7 +60,7 @@ namespace Avalonia.Markup.Xaml.Styling
             }
         }
 
-        bool IResourceNode.HasResources => (Loaded as IResourceProvider)?.HasResources ?? false;
+        bool IResourceNode.HasResources => Loaded?.HasResources ?? false;
 
         IReadOnlyList<IStyle> IStyle.Children => _loaded ?? Array.Empty<IStyle>();
 
@@ -86,9 +86,9 @@ namespace Avalonia.Markup.Xaml.Styling
 
         public bool TryGetResource(object key, out object? value)
         {
-            if (!_isLoading && Loaded is IResourceProvider p)
+            if (!_isLoading)
             {
-                return p.TryGetResource(key, out value);
+                return Loaded.TryGetResource(key, out value);
             }
 
             value = null;