Playing around with BindingProxy

Stylet/Stylet.csproj

@@ -101,6 +101,7 @@
     <Compile Include="Xaml\ActionExtension.cs" />
     <Compile Include="BindableCollection.cs" />
     <Compile Include="BootstrapperBase.cs" />
+    <Compile Include="Xaml\BindingProxy.cs" />
     <Compile Include="Xaml\BoolToVisibilityConverter.cs" />
     <Compile Include="Xaml\CommandAction.cs" />
     <Compile Include="Conductor.cs" />

Stylet/ViewManager.cs

@@ -246,7 +246,7 @@ namespace Stylet
             if (viewAsFrameworkElement != null)
             {
                 logger.Info("Setting {0}'s DataContext to {1}", view, viewModel);
-                viewAsFrameworkElement.DataContext = viewModel;
+                View.SetDataContext(viewAsFrameworkElement, viewModel);
             }
 
             var viewModelAsViewAware = viewModel as IViewAware;

Stylet/Xaml/BindingProxy.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+
+namespace Stylet.Xaml
+{
+    internal class BindingProxy : Freezable
+    {
+        protected override Freezable CreateInstanceCore()
+        {
+            return new BindingProxy();
+        }
+
+        public object Data
+        {
+            get { return (object)GetValue(DataProperty); }
+            set { SetValue(DataProperty, value); }
+        }
+
+        public static readonly DependencyProperty DataProperty =
+            DependencyProperty.Register("Data", typeof(object), typeof(BindingProxy), new PropertyMetadata(null));        
+    }
+}

Stylet/Xaml/View.cs

@@ -4,6 +4,7 @@ using System.Windows;
 using System.Windows.Data;
 using System.Windows.Markup;
 using System.Reflection;
+using Stylet.Logging;
 
 namespace Stylet.Xaml
 {
@@ -12,10 +13,13 @@ namespace Stylet.Xaml
     /// </summary>
     public static class View
     {
-        /// <summary>
-        /// Key which will be used to retrieve the ViewManager associated with the current application, from application's resources
-        /// </summary>
-        public const string ViewManagerResourceKey = "b9a38199-8cb3-4103-8526-c6cfcd089df7";
+        private static readonly ILogger logger = LogManager.GetLogger(typeof(View));
+
+        internal const string ViewManagerResourceKey = "b9a38199-8cb3-4103-8526-c6cfcd089df7";
+
+        internal const string ActionTargetProxyResourceKey = "8b7cb732-8a14-4813-a580-b1f3cccea7b7";
+
+        internal const string DataContextProxyResourceKey = "982a3cb4-68b8-464f-9f65-8835d86d94dd";
 
         /// <summary>
         /// Initial value of the ActionTarget property.
@@ -30,7 +34,23 @@ namespace Stylet.Xaml
         /// <returns>ActionTarget associated with the given object</returns>
         public static object GetActionTarget(DependencyObject obj)
         {
-            return obj.GetValue(ActionTargetProperty);
+            var actionTarget = obj.GetValue(ActionTargetProperty);
+
+            if (actionTarget == InitialActionTarget)
+            {
+                var frameworkElement = obj as FrameworkElement;
+                if (frameworkElement != null)
+                {
+                    var bindingProxy = frameworkElement.TryFindResource(ActionTargetProxyResourceKey) as BindingProxy;
+                    if (bindingProxy != null)
+                    {
+                        logger.Info("ActionTarget not set on object {0}, but a BindingProxy containing an ActionTarget was, so using that", obj);
+                        actionTarget = bindingProxy.Data;
+                    }
+                }
+            }
+
+            return actionTarget;
         }
 
         /// <summary>
@@ -47,7 +67,20 @@ namespace Stylet.Xaml
         /// The object's ActionTarget. This is used to determine what object to call Actions on by the ActionExtension markup extension.
         /// </summary>
         public static readonly DependencyProperty ActionTargetProperty =
-            DependencyProperty.RegisterAttached("ActionTarget", typeof(object), typeof(View), new FrameworkPropertyMetadata(InitialActionTarget, FrameworkPropertyMetadataOptions.Inherits));
+            DependencyProperty.RegisterAttached("ActionTarget", typeof(object), typeof(View), new FrameworkPropertyMetadata(InitialActionTarget, FrameworkPropertyMetadataOptions.Inherits, (d, e) =>
+            {
+                // Also set a binding proxy if we can, in case there's something weird in the way
+                var frameworkElement = d as FrameworkElement;
+                if (frameworkElement == null)
+                    return;
+
+                var bindingProxy = new BindingProxy()
+                {
+                    Data = e.NewValue,
+                };
+                bindingProxy.Freeze();
+                frameworkElement.Resources[ActionTargetProxyResourceKey] = bindingProxy;
+            }));
 
         /// <summary>
         /// Fetch the ViewModel currently associated with a given object
@@ -106,6 +139,44 @@ namespace Stylet.Xaml
                 }
             }));
 
+
+        internal static void SetDataContext(FrameworkElement obj, object value)
+        {
+            obj.DataContext = value;
+            var bindingProxy = new BindingProxy()
+            {
+                Data = value,
+            };
+            obj.Resources[DataContextProxyResourceKey] = bindingProxy;
+        }
+
+        public static bool GetRestoreDataContext(DependencyObject obj)
+        {
+            return (bool)obj.GetValue(RestoreDataContextProperty);
+        }
+
+        public static void SetRestoreDataContext(DependencyObject obj, bool value)
+        {
+            obj.SetValue(RestoreDataContextProperty, value);
+        }
+
+        public static readonly DependencyProperty RestoreDataContextProperty =
+            DependencyProperty.RegisterAttached("RestoreDataContext", typeof(bool), typeof(View), new PropertyMetadata(false, (d, e) =>
+            {
+                if (!(e.NewValue is bool) || !(bool)e.NewValue)
+                    return;
+
+                var frameworkElement = d as FrameworkElement;
+                if (frameworkElement == null)
+                    return;
+
+                var bindingProxy = frameworkElement.Resources[DataContextProxyResourceKey] as BindingProxy;
+                if (bindingProxy == null)
+                    return;
+
+                frameworkElement.DataContext = bindingProxy.Data;
+            }));
+
         /// <summary>
         /// Helper to set the Content property of a given object to a particular View
         /// </summary>

StyletIntegrationTests/ShellView.xaml

@@ -6,7 +6,13 @@
     <DockPanel LastChildFill="False">
         <GroupBox DockPanel.Dock="Top" Header="ShowDialog and DialogResult" Padding="10">
             <StackPanel Orientation="Horizontal">
-                <Button Command="{s:Action ShowDialogAndDialogResult}">Show Dialog</Button>
+                <Button Command="{s:Action ShowDialogAndDialogResult}" Content="Show Dialog">
+                    <Button.ContextMenu>
+                        <ContextMenu>
+                            <MenuItem Header="Foo" Command="{s:Action Foo}"/>
+                        </ContextMenu>
+                    </Button.ContextMenu>
+                </Button>
                 <TextBlock Margin="50,0,0,0">Result: </TextBlock>
                 <TextBlock Margin="10,0,0,0" Text="{Binding ShowDialogAndDialogResultDialogResult}"/>
             </StackPanel>

StyletUnitTests/ViewTests.cs

@@ -5,6 +5,7 @@ using Stylet.Xaml;
 using System;
 using System.Windows;
 using System.Windows.Controls;
+using System.Windows.Controls.Primitives;
 using System.Windows.Data;
 
 namespace StyletUnitTests
@@ -51,7 +52,7 @@ namespace StyletUnitTests
         public void ModelStores()
         {
             var obj = new FrameworkElement();
-            obj.Resources.Add(View.ViewManagerResourceKey, this.viewManager.Object);
+            obj.Resources.Add("b9a38199-8cb3-4103-8526-c6cfcd089df7", this.viewManager.Object);
             View.SetModel(obj, 5);
             Assert.AreEqual(5, View.GetModel(obj));
         }
@@ -60,7 +61,7 @@ namespace StyletUnitTests
         public void ChangingModelCallsOnModelChanged()
         {
             var obj = new FrameworkElement();
-            obj.Resources.Add(View.ViewManagerResourceKey, this.viewManager.Object);
+            obj.Resources.Add("b9a38199-8cb3-4103-8526-c6cfcd089df7", this.viewManager.Object);
             var model = new object();
             View.SetModel(obj, null);
 
@@ -155,5 +156,26 @@ namespace StyletUnitTests
             var content = (TextBlock)element.Content;
             Assert.AreEqual("View for TestViewModel.SubViewModel", content.Text);
         }
+
+        [Test]
+        public void ActionTargetIsRestoredAcrossPopupBoundaries()
+        {
+            Execute.InDesignMode = true;
+
+            var userControl = new UserControl();
+            var grid = new Grid();
+            userControl.Content = grid;
+
+            var button = new Button();
+            grid.Children.Add(button);
+
+            var contextMenu = new ContextMenu();
+            button.ContextMenu = contextMenu;
+
+            var actionTarget = new object();
+
+            View.SetActionTarget(userControl, actionTarget);
+            Assert.AreEqual(actionTarget, View.GetActionTarget(button));
+        }
     }
 }