我相信这是 WPF 中的一个错误(如果重要的话,v4.0),但它已经晚了,也许我错过了一些东西。
出于说明目的,我绑定了一个假示例:
<x:Array x:Key="SampleItems" Type="sys:String">
<sys:String>Foo</sys:String>
<sys:String>Bar</sys:String>
<sys:String>Baz</sys:String>
</x:Array>
这可以工作并显示三个具有相同标题和内容的选项卡:
<TabControl ItemsSource="{StaticResource SampleItems}">
<TabControl.ItemContainerStyle>
<Style TargetType="TabItem">
<Setter Property="Header" Value="{Binding}" />
<Setter Property="Content" Value="{Binding}" />
</Style>
</TabControl.ItemContainerStyle>
</TabControl>
但是,这会引发异常并显示消息“错误 10 指定元素已经是另一个元素的逻辑子元素。首先断开它。”:
<TabControl ItemsSource="{StaticResource SampleItems}">
<TabControl.ItemContainerStyle>
<Style TargetType="TabItem">
<Setter Property="Header">
<Setter.Value>
<!-- Anything here causes this problem. -->
<TextBlock Text="{Binding}"/>
</Setter.Value>
</Setter>
<Setter Property="Content" Value="{Binding}" />
</Style>
</TabControl.ItemContainerStyle>
</TabControl>
需要注意的是,这对于任一 TextBlock 中的任何文本都是可重现的。事实上,我可以用任何 XAML 替换标头 TextBlock 并收到此消息。我无法解释这一点。任何想法,或者这只是一个错误?
问题出现在 VS 设计器中,但这里也是运行时相关堆栈跟踪的一部分:
at System.Windows.FrameworkElement.ChangeLogicalParent(DependencyObject newParent)
at System.Windows.FrameworkElement.AddLogicalChild(Object child)
at System.Windows.Controls.HeaderedContentControl.OnHeaderChanged(Object oldHeader, Object newHeader)
at System.Windows.Controls.HeaderedContentControl.OnHeaderChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
at System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
at System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)
at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)
at System.Windows.StyleHelper.ApplyStyleOrTemplateValue(FrameworkObject fo, DependencyProperty dp)
at System.Windows.StyleHelper.InvalidateContainerDependents(DependencyObject container, FrugalStructList`1& exclusionContainerDependents, FrugalStructList`1& oldContainerDependents, FrugalStructList`1& newContainerDependents)
at System.Windows.StyleHelper.DoStyleInvalidations(FrameworkElement fe, FrameworkContentElement fce, Style oldStyle, Style newStyle)
at System.Windows.StyleHelper.UpdateStyleCache(FrameworkElement fe, FrameworkContentElement fce, Style oldStyle, Style newStyle, Style& styleCache)
at System.Windows.FrameworkElement.OnStyleChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
at System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
at System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)
at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)
at System.Windows.DependencyObject.SetValueCommon(DependencyProperty dp, Object value, PropertyMetadata metadata, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType, Boolean isInternal)
at System.Windows.DependencyObject.SetValue(DependencyProperty dp, Object value)
at System.Windows.Controls.ItemsControl.ApplyItemContainerStyle(DependencyObject container, Object item)
at System.Windows.Controls.ItemsControl.MS.Internal.Controls.IGeneratorHost.PrepareItemContainer(DependencyObject container, Object item)
at System.Windows.Controls.ItemContainerGenerator.System.Windows.Controls.Primitives.IItemContainerGenerator.PrepareItemContainer(DependencyObject container)
at System.Windows.Controls.Panel.GenerateChildren()