如何在wpf中的分层数据模板中显示树视图项的上下文菜单

Question

如何使用分层数据模板在wpf中显示树视图项的上下文菜单？如何仅为CountryTemplate显示上下文菜单:

  <HierarchicalDataTemplate  x:Key="DispTemplate">
        <StackPanel Orientation="Horizontal">
            <TextBlock Text="{Binding Path=Label}" Style="{StaticResource TreeTextStyle}" ToolTip="{Binding Path=Description}" Tag="{Binding Path=Tag}">
            </TextBlock>
        </StackPanel>
    </HierarchicalDataTemplate>
    <HierarchicalDataTemplate  x:Key="BuildingTemplate"  ItemsSource="{Binding Path=Building}" ItemTemplate="{StaticResource BuildingTemplate}">
        <StackPanel Orientation="Horizontal">
            <TextBlock Text="{Binding Path=Label}" Style="{StaticResource TreeTextStyle}" ToolTip="{Binding Path=Description}"/>
        </StackPanel>
    </HierarchicalDataTemplate>
    <HierarchicalDataTemplate  x:Key="CityTemplate"  ItemsSource="{Binding Path=City}" ItemTemplate="{StaticResource CityTemplate}">
        <StackPanel Orientation="Horizontal">
            <TextBlock Text="{Binding Path=Label}" Style="{StaticResource TreeTextStyle}" ToolTip="{Binding Path=Description}"/>
        </StackPanel>
    </HierarchicalDataTemplate>
    <HierarchicalDataTemplate x:Key="CountryTemplate" ItemsSource="{Binding Path=Country}" ItemTemplate="{StaticResource CountryTemplate}">
        <StackPanel Orientation="Horizontal">
            <TextBlock Text="{Binding Path=RootName}" Style="{StaticResource TreeTextStyle}" ToolTip="{Binding Path=Description}"/>
        </StackPanel>
    </HierarchicalDataTemplate>

Answer 1

您还可以将ContextMenu数据模板中的任何可视子项添加到,例如:

<HierarchicalDataTemplate x:Key="CountryTemplate" ItemsSource="{Binding Path=Country}" ItemTemplate="{StaticResource CountryTemplate}">
    <StackPanel Orientation="Horizontal">
        <StackPanel.ContextMenu>
            <ContextMenu>
                 <MenuItem Header="Header" Command="{Binding Command}"/> <!--This command should be in the data context (each country item)-->
            </ContextMenu>
        </StackPanel.ContextMenu>
        <TextBlock Text="{Binding Path=RootName}" Style="{StaticResource TreeTextStyle}" ToolTip="{Binding Path=Description}"/>
    </StackPanel>
</HierarchicalDataTemplate>

Answer 2

上下文菜单无法正常工作的原因之一是因为默认情况下，它们与其他所有内容位于不同的可视化树中，因此DataContext无法找到。

关键的见解是创建一个<Style>定义上下文菜单的 ，然后将该样式附加到目标元素，该元素连接上下文菜单。这会将上下文菜单转换为与DataContext您想要的默认值对齐的可视化树。

首先，创建样式：

<UserControl.Resources>                                                                                                                        
    <ResourceDictionary>

        <!-- For the context menu to work, we must shift it into a style, which means that the context menu is now in a
        visual tree that is more closely related to the current data context. All we have to do then is set the style, 
        which hooks up the context menu. -->
        <Style x:Key="ContextMenuStyle" TargetType="{x:Type StackPanel}">
            <Setter Property="ContextMenu" Value="{DynamicResource TreeViewContextMenu}"/>
        </Style>
        <ContextMenu x:Key="TreeViewContextMenu">
            <MenuItem Header="Test" Command="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}, Path=DataContext.CmdDisplayDetailsGraph}"/>
        </ContextMenu>

然后，将上下文菜单连接到您想要的任何位置，而不会遇到由不同视觉树引起的问题。

示例 1：

<HierarchicalDataTemplate DataType="{x:Type snapshot:Details}" ItemsSource="{Binding DetailsList}">
    <StackPanel Orientation="Vertical" Style="{StaticResource ContextMenuStyle}">
        <ContentPresenter Content="{Binding}" ContentTemplate="{Binding View.DefaultDataRowTemplate}" />
</StackPanel>

示例 2：

<DataTemplate DataType="{x:Type snapshot:InstrumentDetails}">
  <StackPanel Orientation="Vertical" Style="{StaticResource ContextMenuStyle}">                 
      <Grid HorizontalAlignment="Stretch" VerticalAlignment="Center">