Allow binding to attached properties.

Closes #255.

src/Markup/Perspex.Markup.Xaml/Context/PerspexAttachableXamlMember.cs

@@ -0,0 +1,33 @@
+// Copyright (c) The Perspex Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using Perspex.Markup.Xaml.Binding;
+using OmniXaml;
+using OmniXaml.Typing;
+using System.Reflection;
+
+namespace Perspex.Markup.Xaml.Context
+{
+    public class PerspexAttachableXamlMember : AttachableXamlMember
+    {
+        public PerspexAttachableXamlMember(string name,
+            XamlType owner,
+            MethodInfo getter,
+            MethodInfo setter,
+            IXamlTypeRepository xamlTypeRepository,
+            ITypeFeatureProvider featureProvider)
+            : base(name, getter, setter, xamlTypeRepository, featureProvider)
+        {
+        }
+
+        protected override IXamlMemberValuePlugin LookupXamlMemberValueConnector()
+        {
+            return new PerspexXamlMemberValuePlugin(this);
+        }
+
+        public override string ToString()
+        {
+            return "Perspex Attachable XAML Member " + base.ToString();
+        }
+    }
+}

src/Markup/Perspex.Markup.Xaml/Context/PerspexXamlMemberValuePlugin.cs

@@ -5,6 +5,7 @@ using System;
 using System.Linq;
 using System.Reactive.Linq;
 using System.Reflection;
+using System.Runtime.CompilerServices;
 using Glass;
 using OmniXaml.ObjectAssembler;
 using OmniXaml.Typing;
@@ -16,9 +17,9 @@ namespace Perspex.Markup.Xaml.Context
 {
     public class PerspexXamlMemberValuePlugin : MemberValuePlugin
     {
-        private readonly XamlMember _xamlMember;
+        private readonly MutableXamlMember _xamlMember;
 
-        public PerspexXamlMemberValuePlugin(XamlMember xamlMember) 
+        public PerspexXamlMemberValuePlugin(MutableXamlMember xamlMember) 
             : base(xamlMember)
         {
             _xamlMember = xamlMember;
@@ -73,6 +74,7 @@ namespace Perspex.Markup.Xaml.Context
             else
             {
                 var perspexObject = instance as PerspexObject;
+                var attached = _xamlMember as PerspexAttachableXamlMember;
 
                 if (perspexObject == null)
                 {
@@ -80,13 +82,31 @@ namespace Perspex.Markup.Xaml.Context
                         $"Cannot bind to an object of type '{instance.GetType()}");
                 }
 
-                var property = perspexObject.GetRegisteredProperties()
-                    .FirstOrDefault(x => x.Name == _xamlMember.Name);
+                PerspexProperty property;
+                string propertyName;
+
+                if (attached == null)
+                {
+                    propertyName = _xamlMember.Name;
+                    property = perspexObject.GetRegisteredProperties()
+                        .FirstOrDefault(x => x.Name == propertyName);
+                }
+                else
+                {
+                    // Ensure the OwnerType's static ctor has been run.
+                    RuntimeHelpers.RunClassConstructor(attached.DeclaringType.UnderlyingType.TypeHandle);
+
+                    propertyName = attached.DeclaringType.UnderlyingType.Name + '.' + _xamlMember.Name;
+
+                    property = perspexObject.GetRegisteredProperties()
+                        .Where(x => x.IsAttached && x.OwnerType == attached.DeclaringType.UnderlyingType)
+                        .FirstOrDefault(x => x.Name == _xamlMember.Name);
+                }
 
                 if (property == null)
                 {
                     throw new InvalidOperationException(
-                        $"Cannot find '{_xamlMember.Name}' on '{instance.GetType()}");
+                        $"Cannot find '{propertyName}' on '{instance.GetType()}");
                 }
 
                 var binding = new XamlBinding

src/Markup/Perspex.Markup.Xaml/Context/PerspexXamlType.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 using System;
+using System.Reflection;
 using OmniXaml;
 using OmniXaml.Typing;
 using Perspex.Markup.Xaml.Binding;
@@ -22,6 +23,14 @@ namespace Perspex.Markup.Xaml.Context
             return new PerspexXamlMember(name, this, TypeRepository, FeatureProvider);
         }
 
+        protected override AttachableXamlMember LookupAttachableMember(string name)
+        {
+            // OmniXAML seems to require a getter and setter even though we don't use them.
+            var getter = UnderlyingType.GetTypeInfo().GetDeclaredMethod("Get" + name);
+            var setter = UnderlyingType.GetTypeInfo().GetDeclaredMethod("Set" + name);
+            return new PerspexAttachableXamlMember(name, this, getter, setter, TypeRepository, FeatureProvider);
+        }
+
         public override string ToString()
         {
             return "Perspex XAML Type " + base.ToString();

src/Markup/Perspex.Markup.Xaml/Perspex.Markup.Xaml.csproj

@@ -42,6 +42,7 @@
     <Compile Include="Binding\TargetBindingEndpoint.cs" />
     <Compile Include="Binding\XamlBinding.cs" />
     <Compile Include="Binding\XamlBindingDefinition.cs" />
+    <Compile Include="Context\PerspexAttachableXamlMember.cs" />
     <Compile Include="Converters\ColorTypeConverter.cs" />
     <Compile Include="Converters\KeyGestureConverter.cs" />
     <Compile Include="Converters\RelativePointTypeConverter.cs" />