Started adding StaticResource.

src/Markup/Avalonia.Markup.Xaml/Avalonia.Markup.Xaml.csproj

@@ -34,6 +34,7 @@
         <Compile Include="Converters\MatrixTypeConverter.cs" />
         <Compile Include="Converters\RectTypeConverter.cs" />
         <Compile Include="Converters\SetterValueTypeConverter.cs" />
+        <Compile Include="MarkupExtensions\StaticResourceExtension.cs" />
         <Compile Include="MarkupExtensions\StyleIncludeExtension.cs" />
         <Compile Include="PortableXaml\AvaloniaXamlContext.cs" />
         <Compile Include="PortableXaml\XamlBinding.cs" />

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

@@ -0,0 +1,45 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System;
+using System.ComponentModel;
+using Avalonia.Controls;
+using Portable.Xaml;
+using Portable.Xaml.ComponentModel;
+using Portable.Xaml.Markup;
+
+namespace Avalonia.Markup.Xaml.MarkupExtensions
+{
+    public class StaticResourceExtension : MarkupExtension
+    {
+        public StaticResourceExtension()
+        {
+        }
+
+        public StaticResourceExtension(string resourceKey)
+        {
+            ResourceKey = resourceKey;
+        }
+
+        public string ResourceKey { get; set; }
+
+        public override object ProvideValue(IServiceProvider serviceProvider)
+        {
+            var context = (ITypeDescriptorContext)serviceProvider;
+            var schemaContext = context.GetService<IXamlSchemaContextProvider>()?.SchemaContext;
+            var ambientProvider = context.GetService<IAmbientProvider>();
+            var resourceProviderType = schemaContext.GetXamlType(typeof(IResourceProvider));
+            var resourceProviders = ambientProvider.GetAllAmbientValues(resourceProviderType);
+
+            foreach (IResourceProvider resourceProvider in resourceProviders)
+            {
+                if (resourceProvider.TryGetResource(ResourceKey, out var value))
+                {
+                    return value;
+                }
+            }
+
+            return AvaloniaProperty.UnsetValue;
+        }
+    }
+}

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

@@ -0,0 +1,125 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System;
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml.Data;
+using Avalonia.Media;
+using Avalonia.Styling;
+using Avalonia.UnitTests;
+using Xunit;
+
+namespace Avalonia.Markup.Xaml.UnitTests.Xaml
+{
+    public class StaticResourceTests
+    {
+        [Fact]
+        public void StaticResource_Style_Can_Be_Assigned_To_Property()
+        {
+            var xaml = @"
+<UserControl xmlns='https://github.com/avaloniaui'
+             xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'>
+    <UserControl.Resources>
+        <SolidColorBrush x:Key='brush'>#ff506070</SolidColorBrush>
+    </UserControl.Resources>
+
+    <Border Name='border' Background='{StaticResource brush}'/>
+</UserControl>";
+
+            var loader = new AvaloniaXamlLoader();
+            var userControl = (UserControl)loader.Load(xaml);
+            var border = userControl.FindControl<Border>("border");
+
+            var brush = (SolidColorBrush)border.Background;
+            Assert.Equal(0xff506070, brush.Color.ToUint32());
+        }
+
+        [Fact]
+        public void StaticResource_From_Style_Can_Be_Assigned_To_Property()
+        {
+            var xaml = @"
+<UserControl xmlns='https://github.com/avaloniaui'
+             xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'>
+    <UserControl.Styles>
+        <Style>
+            <Style.Resources>
+                <SolidColorBrush x:Key='brush'>#ff506070</SolidColorBrush>
+            </Style.Resources>
+        </Style>
+    </UserControl.Styles>
+
+    <Border Name='border' Background='{StaticResource brush}'/>
+</UserControl>";
+
+            var loader = new AvaloniaXamlLoader();
+            var userControl = (UserControl)loader.Load(xaml);
+            var border = userControl.FindControl<Border>("border");
+
+            var brush = (SolidColorBrush)border.Background;
+            Assert.Equal(0xff506070, brush.Color.ToUint32());
+        }
+
+        [Fact]
+        public void StaticResource_Can_Be_Assigned_To_Setter()
+        {
+            using (StyledWindowNoTheme())
+            {
+                var xaml = @"
+<Window xmlns='https://github.com/avaloniaui'
+        xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'>
+    <Window.Resources>
+        <SolidColorBrush x:Key='brush'>#ff506070</SolidColorBrush>
+    </Window.Resources>
+    <Window.Styles>
+        <Style Selector='Button'>
+            <Setter Property='Background' Value='{StaticResource brush}'/>
+        </Style>
+    </Window.Styles>
+    <Button Name='button'/>
+</Window>";
+
+                var loader = new AvaloniaXamlLoader();
+                var window = (Window)loader.Load(xaml);
+                var button = window.FindControl<Button>("button");
+                var brush = (SolidColorBrush)button.Background;
+
+                Assert.Equal(0xff506070, brush.Color.ToUint32());
+            }
+        }
+
+        [Fact]
+        public void StaticResource_From_Style_Can_Be_Assigned_To_Setter()
+        {
+            using (StyledWindowNoTheme())
+            {
+                var xaml = @"
+<Window xmlns='https://github.com/avaloniaui'
+        xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'>
+    <Window.Styles>
+        <Style>
+            <Style.Resources>
+                <SolidColorBrush x:Key='brush'>#ff506070</SolidColorBrush>
+            </Style.Resources>
+        </Style>
+        <Style Selector='Button'>
+            <Setter Property='Background' Value='{StaticResource brush}'/>
+        </Style>
+    </Window.Styles>
+    <Button Name='button'/>
+</Window>";
+
+                var loader = new AvaloniaXamlLoader();
+                var window = (Window)loader.Load(xaml);
+                var button = window.FindControl<Button>("button");
+                var brush = (SolidColorBrush)button.Background;
+
+                Assert.Equal(0xff506070, brush.Color.ToUint32());
+            }
+        }
+
+        private IDisposable StyledWindowNoTheme()
+        {
+            return UnitTestApplication.Start(TestServices.StyledWindow.With(theme: () => new Styles()));
+        }
+    }
+}