ドラッグ＆ドロップはScatterViewItemのために働いているが、ラベル

Question

のために私はラベルをドラッグするために、このメソッドを使用しない：

private void Label_PreviewContactDown(object sender, ContactEventArgs e) 
     { 

       FrameworkElement findSource = e.OriginalSource as FrameworkElement; 
       Label draggedElement = null; 

       while (draggedElement == null && findSource != null) 
       { 
        if ((draggedElement = findSource as Label) == null) 
        { 
         findSource = VisualTreeHelper.GetParent(findSource) as FrameworkElement; 
        } 
       } 

       if (draggedElement == null) 
       { 
        return; 
       } 

       SourceFile data = draggedElement.Tag as SourceFile; 



       data.DraggedElement = draggedElement; 

       ContentControl cursorVisual = new ContentControl() 
       { 
        Content = data, 
        // Style = manager.window.FindResource("CursorStyle") as Style 

       }; 

       List<InputDevice> devices = new List<InputDevice>(); 
       devices.Add(e.Contact); 


       ItemsControl dragSource = ItemsControl.ItemsControlFromItemContainer(draggedElement); 

       bool startDragOkay = 
        SurfaceDragDrop.BeginDragDrop(
         dragSource,     // The ScatterView object that the cursor is dragged out from. 
         draggedElement,    // The ScatterViewItem object that is dragged from the drag source. 
         cursorVisual,    // The visual element of the cursor. 
         data, // The data attached with the cursor. 
         devices,     // The input devices that start dragging the cursor. 
         DragDropEffects.Move);  // The allowed drag-and-drop effects of the operation. 

       if (startDragOkay) 
       { 
        e.Handled = true; 
        draggedElement.Visibility = Visibility.Hidden; 
       } 

     } 

全く同じコードがScatterViewItemsのために動作しますが、私はラベルでこれをしようとした場合、それはdoesntの。何かヒント？

problemisは以下：ルーティングイベントの戦略を使用しても意味がありません

System.ArgumentNullException was unhandled 
    Message=Value cannot be null. 
Parameter name: dragSource 
    Source=Microsoft.Surface.Presentation 
    ParamName=dragSource 
    StackTrace: 
     at Microsoft.Surface.Presentation.SurfaceDragDrop.BeginDragDrop[T](FrameworkElement dragSource, FrameworkElement draggedElement, FrameworkElement cursorVisual, Object data, IEnumerable`1 inputDevices, DragDropEffects allowedEffects) 
     at Prototype_Concept_1.TaggingTagVisualization.Label_PreviewContactDown(Object sender, ContactEventArgs e) in C:\Users\Roflcoptr\Documents\Visual Studio 2008\Projects\Prototype_Concept_1\Prototype_Concept_1\TaggingTagVisualization.xaml.cs:line 111 
     at Microsoft.Surface.Presentation.ContactEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget) 
     at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target) 
     at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs) 
     at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised) 
     at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args) 
     at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted) 
     at System.Windows.Input.InputManager.ProcessStagingArea() 
     at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input) 
     at Microsoft.Surface.Presentation.InputSurfaceProviderBase.DoProcessInput(Object obj) 
     at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) 
     at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) 
     at System.Windows.Threading.Dispatcher.WrappedInvoke(Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) 
     at System.Windows.Threading.DispatcherOperation.InvokeImpl() 
     at System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state) 
     at System.Threading.ExecutionContext.runTryCode(Object userData) 
     at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData) 
     at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) 
     at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) 
     at System.Windows.Threading.DispatcherOperation.Invoke() 
     at System.Windows.Threading.Dispatcher.ProcessQueue() 
     at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) 
     at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) 
     at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) 
     at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) 
     at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) 
     at System.Windows.Threading.Dispatcher.WrappedInvoke(Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) 
     at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Boolean isSingleParameter) 
     at System.Windows.Threading.Dispatcher.Invoke(DispatcherPriority priority, Delegate method, Object arg) 
     at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam) 
     at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg) 
     at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame) 
     at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame) 
     at System.Windows.Threading.Dispatcher.Run() 
     at System.Windows.Application.RunDispatcher(Object ignore) 
     at System.Windows.Application.RunInternal(Window window) 
     at System.Windows.Application.Run(Window window) 
     at System.Windows.Application.Run() 
     at Prototype_Concept_1.App.Main() in C:\Users\Roflcoptr\Documents\Visual Studio 2008\Projects\Prototype_Concept_1\Prototype_Concept_1\obj\Debug\App.g.cs:line 0 
     at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args) 
     at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args) 
     at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() 
     at System.Threading.ThreadHelper.ThreadStart_Context(Object state) 
     at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) 
     at System.Threading.ThreadHelper.ThreadStart() 
    InnerException: 

Answer 1

、すべてが無地である：

FrameworkElement ds = (FrameworkElement)sender; 
//... data, cursor and devices 
var dragCursor = 
      SurfaceDragDrop.BeginDragDrop(
       ds, 
       ds, 
       cursorVisual, 
       data, 
       devices, 
       DragDropEffects.Move); 
if (dragCursor != null) 
    e.Handled = true; 

私はサーフェスツールキットでそれをテストしたので、いくつかの違いがあることができ。