削除影が、私はいつもScatterViewItemから影を削除するには、このコードを使用し

Question

が機能していません。私はいつもこの例外を取得：

System.NullReferenceException was unhandled 
    Message=Object reference not set to an instance of an object. 
    Source=Prototype_Concept_2 
    StackTrace: 
     at Prototype_Concept_2.PackageView.expand(Package pck) in C:\Users\Roflcoptr\Documents\Visual Studio 2008\Projects\Prototype_Concept_2\Prototype_Concept_2\PackageView.xaml.cs:line 45 
     at Prototype_Concept_2.PackageView..ctor(SourceFile focus) in C:\Users\Roflcoptr\Documents\Visual Studio 2008\Projects\Prototype_Concept_2\Prototype_Concept_2\PackageView.xaml.cs:line 31 
     at Prototype_Concept_2.DetailChooser.ShowPackage_PreviewContactDown(Object sender, ContactEventArgs e) in C:\Users\Roflcoptr\Documents\Visual Studio 2008\Projects\Prototype_Concept_2\Prototype_Concept_2\DetailChooser.xaml.cs:line 213 
     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_2.App.Main() in C:\Users\Roflcoptr\Documents\Visual Studio 2008\Projects\Prototype_Concept_2\Prototype_Concept_2\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: 

は、これはラインssc = svi.Template.FindName("shadow", svi) as Microsoft.Surface.Presentation.Generic.SurfaceShadowChrome; であっNullReferenceなければなりませんが、私はなぜ知らないことを意味します。

Answer 1

ApplyTemplateはfalseを返します。そのため、テンプレートは適用されません。つまり、nullです。これはNullReferenceExceptionについて説明しています。あなたができることは、ScatterViewItemのLoadedイベントに代入するイベントハンドラをアタッチし、ハンドラで同じことをすることです。 WPFでは、Loadedイベントが発生したときにテンプレートが常に適用されています

ScatterViewItem svi = new ScatterViewItem(); 
svi.Background = new SolidColorBrush(Colors.Transparent); 
svi.ShowsActivationEffects = false; 
svi.BorderBrush = System.Windows.Media.Brushes.Transparent; 

RoutedEventHandler loadedEventHandler = null; 
loadedEventHandler = new RoutedEventHandler(delegate 
{ 
    svi.Loaded -= loadedEventHandler; 
    Microsoft.Surface.Presentation.Generic.SurfaceShadowChrome ssc; 
    ssc = svi.Template.FindName("shadow", svi) as Microsoft.Surface.Presentation.Generic.SurfaceShadowChrome; 
    ssc.Visibility = Visibility.Hidden; 
}); 
svi.Loaded += loadedEventHandler;