WPF MenuItem IsChecked Binding无法正常工作

Question

任何人都知道为什么菜单项绑定不起作用？

<ToggleButton Name="toggleButton" Checked="checkBoxPublish_Checked" >
    <ToggleButton.Resources>
        <converters:BooleanToHiddenVisibility x:Key="boolToVis"/>
    </ToggleButton.Resources>
    <Grid>
        <Image  Height="auto"  HorizontalAlignment="Left" Margin="5" Name="image1" Stretch="Fill" VerticalAlignment="Top" Width="auto"  />
        <Viewbox >
            <TextBlock Text="Blocked" Opacity="0.7" Foreground="Red"   Visibility="{Binding Path=IsChecked, ElementName=toggleButton, Converter={StaticResource boolToVis}}"/>
        </Viewbox>
    </Grid>
    <ToggleButton.ContextMenu>
        <ContextMenu StaysOpen="True" >
            <MenuItem x:Name="menuItemBlock" Header="Block" Click="menuItemClick"  IsCheckable="True" IsChecked="{Binding ElementName=toggleButton, Path=IsChecked}"/>
            <MenuItem x:Name="menuItemIgnorePtz" Header="Ignore Ptz" Click="menuItemClick"  IsCheckable="True" />
        </ContextMenu>
    </ToggleButton.ContextMenu>
</ToggleButton>

Answer 1

我猜这是使用数据绑定时遇到问题的上下文菜单.

togglebutton不在contextmenu的逻辑树中,因此无法使用ElementName找到togglebutton,请参阅http://blogs.msdn.com/b/mikehillberg/archive/2008/05/23/of-logical-and -视觉树功能于wpf.aspx

这就是为什么在VS的输出窗口中出现该绑定的错误:

System.Windows.Data错误:4:无法找到引用'ElementName = toggleButton'的绑定源.BindingExpression:路径=器isChecked; 的DataItem = NULL; target元素是'MenuItem'(Name ='menuItemBlock'); target属性是'IsChecked'(类型'布尔')

要解决此问题,请使用FindAncestor查找切换按钮:

<MenuItem 
  Header="Block" 
  IsCheckable="True" 
  IsChecked="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=ContextMenu}, Path=PlacementTarget.IsChecked}" />