Perché l'albero di clic genera "System.Windows.Documents.Run" non è un InvalidOperationException di Visual o Visual3D?

Question

A volte, facendo clic con il tasto destro del mouse su treeviewitem, i risultati non vengono gestiti InvalidOperationException. Nel codice sottostante seleziono la riga su cui è stato fatto clic:

static TreeViewItem VisualUpwardSearch(DependencyObject source) 
    { 
     while (source != null && !(source is TreeViewItem)) 
      source = VisualTreeHelper.GetParent(source); 

     return source as TreeViewItem; 
    } 

    private void OnPreviewMouseRightButtonDown(object sender, MouseButtonEventArgs e) 
    { 
      TreeViewItem treeViewItem = VisualUpwardSearch(e.OriginalSource as DependencyObject); 

      if (treeViewItem != null) 
      { 
       treeViewItem.Focus(); 
       e.Handled = true; 
      } 
    } 

Secondo stacktrace sopra è la fonte del problema.

XAML:

<UserControl.Resources> 
    <HierarchicalDataTemplate ItemsSource="{Binding ClassesItemsSource}" DataType="{x:Type pnls:FavoriteObjectTableViewModel}"> 
     <StackPanel Orientation="Horizontal"> 
      <Image Source="{Binding Converter={StaticResource nameToBitmapSource}}" DataContext="{Binding Bitmap}" /> 
      <Label Content="{Binding TableName}"/> 
     </StackPanel> 
    </HierarchicalDataTemplate> 
    <DataTemplate DataType="{x:Type pnls:FavoriteObjectClassViewModel}"> 
     <StackPanel Orientation="Horizontal"> 
      <Image Source="{Binding Bitmap, Converter={StaticResource UriToCachedImageConverter}}"/> 
      <Label Content="{Binding ClassName}"/> 
     </StackPanel> 
    </DataTemplate> 
</UserControl.Resources> 

<TreeView Name="Insert_ObjectTreeIE" Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="2" ItemsSource="{Binding TablesItemsSource}"> 
     <TreeView.ItemContainerStyle> 
      <Style TargetType="TreeViewItem"> 
       <Setter Property="IsSelected" Value="{Binding IsSelected}" /> 
       <Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}" /> 
       <EventSetter Event="PreviewMouseRightButtonDown" Handler="OnPreviewMouseRightButtonDown"></EventSetter> 
       <EventSetter Event="MouseDoubleClick" Handler="OnMouseDoubleClick" /> 
      </Style> 
     </TreeView.ItemContainerStyle> 
</TreeView> 

Stacktrace:

e.StackTrace " at MS.Internal.Media.VisualTreeUtils.AsVisual(DependencyObject element, Visual& visual, Visual3D& visual3D)\r\n 
at MS.Internal.Media.VisualTreeUtils.AsNonNullVisual(DependencyObject element, Visual& visual, Visual3D& visual3D)\r\n 
at System.Windows.Media.VisualTreeHelper.GetParent(DependencyObject reference)\r\n 
at Tekla.Nis.Application.Shared.UI.Panels.FavoriteObjectsView.VisualUpwardSearch(DependencyObject source) in c:\\XXX\\161wpf\\src\\SharedAppFeature\\Panels\\FavoriteObjectsView.xaml.cs:line 45\r\n 
at Application.Shared.UI.Panels.FavoriteObjectsView.OnPreviewMouseRightButtonDown(Object sender, MouseButtonEventArgs e) in c:\\XXX\\161wpf\\src\\NisSharedAppFeature\\Panels\\FavoriteObjectsView.xaml.cs:line 52\r\n 
at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)\r\n 
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)\r\n 
at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)\r\n 
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)\r\n 
at System.Windows.UIElement.ReRaiseEventAs(DependencyObject sender, RoutedEventArgs args, RoutedEvent newEvent)\r\n 
at System.Windows.UIElement.OnPreviewMouseDownThunk(Object sender, MouseButtonEventArgs e)\r\n 
at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)\r\n 
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)\r\n at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)\r\n 
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)\r\n 
at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)\r\n at System.Windows.ContentElement.RaiseTrustedEvent(RoutedEventArgs args)\r\n 
at System.Windows.Input.InputManager.ProcessStagingArea()\r\n 
at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)\r\n 
at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)\r\n 
at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel)\r\n 
at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled)\r\n 
at System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)\r\n 
at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)\r\n at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)\r\n 
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)\r\n 
at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)\r\n 
at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)\r\n 
at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)\r\n 
at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)\r\n 
at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)\r\n 
at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)\r\n 
at System.Windows.Application.RunDispatcher(Object ignore)\r\n 
at System.Windows.Application.RunInternal(Window window)\r\n 
at System.Windows.Application.Run(Window window)\r\n 
at System.Windows.Application.Run()\r\n at "my application start location" 

posso riprodurre questo solo a volte. Il mio collega ha detto che l'elemento clic sinistro 1 e il clic destro 2 lo produce ogni volta in un determinato albero.

Answer 1

I problemi si verificano quando si fa clic in qualche punto nel testo dell'etichetta. In questo caso, lo e.OriginalSource sarà un oggetto Run che fa parte della composizione interna di Label o TextBox. L'elemento Run non eredita da una classe Visual, quindi non può essere una parte dell'albero visivo, in questo caso lo VisualTreeHelper.GetParent(source); genererà InvalidOperationException.

La soluzione più semplice è quello di rendere ogni controllo di testo (Label nel tuo caso) IsHitTestVisible="False", questo escludere questi controlli dalla logica di rilevamento del contatto, il che significa che non sarà mai la e.OriginalSource di un evento, invece è genitore sarà raccolto e molto probabilmente il genitore sarà un elemento Visual.