WPF NotifyIcon

--------------
CHG   DataContext now also set on ContextMenu property. Revamped DataContext handling, which
      now not only checks whether DataContext is not null, but also leaves DataContext of
      controls unchanged, if the DataContext is bound.
CHG   Some documentation changes and cleanup, added class diagram.

git-svn-id: https://svn.evolvesoftware.ch/repos/evolve.net/WPF/NotifyIcon@100 9f600761-6f11-4665-b6dc-0185e9171623

Source/NotifyIconWpf/TaskbarIcon.Declarations.cs

@@ -557,7 +557,24 @@ namespace Hardcodet.Wpf.TaskbarNotification
 
     #endregion
 
-    #region DataContext dependency property override
+    #region DataContext dependency property override / target update
+
+    /// <summary>
+    /// Updates the <see cref="FrameworkElement.DataContextProperty"/> of a given
+    /// <see cref="FrameworkElement"/>. This method only updates target elements
+    /// that do not already have a data context of their own, and either assigns
+    /// the <see cref="FrameworkElement.DataContext"/> of the NotifyIcon, or the
+    /// NotifyIcon itself, if no data context was assigned at all.
+    /// </summary>
+    private void UpdateDataContext(FrameworkElement target, object oldDataContextValue, object newDataContextValue)
+    {
+      if (target != null && !target.IsDataContextDataBound() && Equals(oldDataContextValue, target.DataContext))
+      {
+        //assign own data context, if available. If there is no data
+        //context at all, assign NotifyIcon itself.
+        target.DataContext = newDataContextValue ?? this;
+      }
+    }
 
     /// <summary>
     /// A static callback listener which is being invoked if the
@@ -586,24 +603,58 @@ namespace Hardcodet.Wpf.TaskbarNotification
       object newValue = e.NewValue;
       object oldValue = e.OldValue;
 
-      //replace custom data context for popup and tooltip, if
-      //they are reflecting the data context's data context
-      var popup = TrayPopupResolved;
-      var toolTip = TrayToolTipResolved;
-
-      if (popup != null && Equals(popup.DataContext, oldValue))
-      {
-        popup.DataContext = newValue;
-      }
-
-      if (toolTip != null && Equals(toolTip.DataContext, oldValue))
-      {
-        toolTip.DataContext = newValue;
-      }
+      //replace custom data context for ToolTips, Popup, and
+      //ContextMenu
+      UpdateDataContext(TrayPopupResolved, oldValue, newValue);
+      UpdateDataContext(TrayToolTipResolved, oldValue, newValue);
+      UpdateDataContext(ContextMenu, oldValue, newValue);
     }
 
     #endregion
 
+    #region ContextMenu dependency property override
+
+    /// <summary>
+    /// A static callback listener which is being invoked if the
+    /// <see cref="FrameworkElement.ContextMenuProperty"/> dependency property has
+    /// been changed. Invokes the <see cref="OnContextMenuPropertyChanged"/>
+    /// instance method of the changed instance.
+    /// </summary>
+    /// <param name="d">The currently processed owner of the property.</param>
+    /// <param name="e">Provides information about the updated property.</param>
+    private static void ContextMenuPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
+    {
+      TaskbarIcon owner = (TaskbarIcon)d;
+      owner.OnContextMenuPropertyChanged(e);
+    }
+
+
+    /// <summary>
+    /// Releases the old and updates the new <see cref="ContextMenu"/> property
+    /// in order to reflect both the NotifyIcon's <see cref="FrameworkElement.DataContext"/>
+    /// property and have the <see cref="ParentTaskbarIconProperty"/> assigned.
+    /// </summary>
+    /// <param name="e">Provides information about the updated property.</param>
+    private void OnContextMenuPropertyChanged(DependencyPropertyChangedEventArgs e)
+    {
+      if (e.OldValue != null)
+      {
+        //remove the taskbar icon reference from the previously used element
+        SetParentTaskbarIcon((DependencyObject)e.OldValue, null);
+      }
+
+      if (e.NewValue != null)
+      {
+        //set this taskbar icon as a reference to the new tooltip element
+        SetParentTaskbarIcon((DependencyObject)e.NewValue, this);
+      }
+
+      UpdateDataContext((ContextMenu) e.NewValue, null, DataContext);
+    }
+
+    #endregion
+
+
 
     #region DoubleClickCommand dependency property
 
@@ -1752,7 +1803,12 @@ namespace Hardcodet.Wpf.TaskbarNotification
       //register change listener for the DataContext property
       md = new FrameworkPropertyMetadata(new PropertyChangedCallback(DataContextPropertyChanged));
       DataContextProperty.OverrideMetadata(typeof(TaskbarIcon), md);
+
+      //register change listener for the ContextMenu property
+      md = new FrameworkPropertyMetadata(new PropertyChangedCallback(ContextMenuPropertyChanged));
+      ContextMenuProperty.OverrideMetadata(typeof(TaskbarIcon), md);
     }
 
+
   }
 }