WPF—多重绑定和跨层级绑定

<!--树节点展开属性由多个因素决定，故而采用多重绑定 --> 
<Setter Property="IsExpanded">
    <Setter.Value>
        <MultiBinding Converter="{StaticResource EnableConverter}" UpdateSourceTrigger="PropertyChanged">
            <!--指定绑定的ItemSource，而非默认的treeView ItemSource --> 
            <Binding RelativeSource="{RelativeSource AncestorType=Window}" Path="DataContext.Criteria"/>
            <Binding Path="SubNodes"/>
        </MultiBinding>
    </Setter.Value>
</Setter>

 <TextBlock  Grid.Row="5" Grid.Column="3">
  <TextBlock.IsEnabled>
    <MultiBinding Converter="{StaticResource MultiStringStateConverter}">
        <Binding Path="ZfMuscle"/>
        <Binding Path="ZfResult"/>
    </MultiBinding>
  </TextBlock.IsEnabled>
 </TextBlock>

// 继承IMultiValueConverter接口
public class EnableConverter : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
    {
        var node = (Node)values[0];// 对应第一个绑定
        var index = (int)values[1];// 对应第二个绑定
        // do something
    }
    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}