滚动时FlowDocumentScrollViewer崩溃

Question

我正在开发一个wpf应用程序，它有一个绑定到一个FlowDocument的FlowDocumentScrollViewer。当滚动FlowDocumentScrollViewer时，我得到了一个InvalidOperationException：'This TextNavigator‘没有限定作用域的文本元素。这会导致应用程序崩溃。

异常详细信息：

System.InvalidOperationException: 'This TextNavigator' has no scoping text element.
at System.Windows.Documents.TextPointer.MoveToElementEdge(ElementEdge edge)
at System.Windows.Documents.TextPointer.System.Windows.Documents.ITextPointer.MoveToElementEdge(ElementEdge edge)
at System.Windows.Documents.TextPointerBase.GetFollowingNonMergeableInlineContentStart(ITextPointer position)
at System.Windows.Documents.TextSelection.get_PropertyPosition()
at System.Windows.Documents.TextSelection.GetCurrentValue(DependencyProperty formattingProperty)
at System.Windows.Documents.TextSelection.GetCaretBrush(TextEditor textEditor)
at System.Windows.Documents.TextSelection.UpdateCaretStateWorker(Object o)
at System.Windows.Documents.TextSelection.UpdateCaretState(CaretScrollMethod caretScrollMethod)
at System.Windows.Documents.TextSelection.System.Windows.Documents.ITextRange.NotifyChanged(Boolean disableScroll, Boolean skipEvents)
at System.Windows.Documents.TextRangeBase.EndChange(ITextRange thisRange, Boolean disableScroll, Boolean skipEvents)
at System.Windows.Documents.TextRange.System.Windows.Documents.ITextRange.EndChange(Boolean disableScroll, Boolean skipEvents)
at System.Windows.Documents.TextRange.ChangeBlock.System.IDisposable.Dispose()
at System.Windows.Documents.TextEditorMouse.OnMouseMoveWithFocus(TextEditor This, MouseEventArgs e)
at System.Windows.Documents.TextEditorMouse.OnMouseMove(Object sender, MouseEventArgs e)
at System.Windows.Input.MouseEventArgs.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.RaiseTrustedEvent(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 System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel)
at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
at System.Windows.Interop.HwndSource.InputFilterMessage(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, Int32 numArgs)
at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler) 

在生成FlowDocument时，我不会得到任何异常。我一直在网上搜索，但没有发现任何有用的信息。

Answer 1

我没有直接的解释，但我今天遇到了同样的例外。在我的例子中，答案是：不要选择一个空的以及任何“更适合”的FlowDocument组件。

这是我的xaml，它是一个用户控件，我创建一个实例并将它放在我的窗口中(它应该像一个TabControl的第一个TabControl中的“主页”，在这里我决定在“瑞士骑士”应用程序中做什么)。注意，BlockUIContainer (用于托管类似注释的UI，粘贴任何文本，并将其保存到转储文件)，我注释掉了它的内容：

    <DockPanel HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
        
        <FlowDocumentScrollViewer 
            IsToolBarVisible="False" Zoom="60" 
            HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
            <FlowDocument>
                <Paragraph><Run FontSize="24">Quick start :</Run></Paragraph>
                <List MarkerOffset="16" LineHeight="16">
                    <ListItem><Paragraph>Open application directory in <Hyperlink NavigateUri="" RequestNavigate="ExploreAppDir_RequestNavigate">Explorer</Hyperlink>...</Paragraph></ListItem>
                    <ListItem><Paragraph>Manage <Hyperlink NavigateUri="" RequestNavigate="GalleryManager_RequestNavigate">images gallery</Hyperlink>...</Paragraph></ListItem>
                    <ListItem><Paragraph>Create a model...</Paragraph></ListItem>
                    <ListItem><Paragraph>Launch server...</Paragraph></ListItem>
                </List>
                
                <BlockUIContainer>
                    <!--DockPanel Height="100">
                        <TextBox DockPanel.Dock="Top" />
                        <Grid />
                    </DockPanel-->
                </BlockUIContainer>
                
                <Paragraph>
                    <Bold>What to do next ?</Bold>
                </Paragraph>
            </FlowDocument>
        </FlowDocumentScrollViewer>
        
    </DockPanel>

我注释掉了BlockUIContainer的内容，当我开始从文本“下一步要做什么”中选择BlockUIContainer组件时，会得到异常。

当我取消对BlockUIContainer内容的注释时，即现在我有了那个文本框和一个占位符网格，我可以选择任何东西(任何FlowDocument项)，遍历BlockUIContainer组件(包括BlockUIContainer)。(它的文本框)，以及它之外的(无一例外地是)。

我一点也不明白这个例外。根据调用堆栈中的单词，当没有子内容时，空的BlockUIContainer似乎不能转发内容选择边界，我发现这有点疏忽。OP的问题发生在他滚动时，但并不表示他有任何选择，因此很可能是另一个文本边界问题。