绑定TabItem上下文菜单可见性到DataContext

Question

我试图将上下文菜单的可见性绑定到数据上下文的closeclose属性。该绑定适用于同一作用域内的其他控件。

<TabControl.ItemContainerStyle>
<Style TargetType="{x:Type TabItem}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type TabItem}">
                <Grid>
                    <Grid.Margin>
                        <Thickness Left="0" Top="0" Right="{StaticResource LBFTabMargin}"
                           Bottom="0" />
                    </Grid.Margin>
                    <Border Background="LightGray" BorderBrush="DarkGray" BorderThickness="1" x:Name="ForegroundBorder" />
                    <Grid>
                        <Grid Margin="{StaticResource LBFSmallThickness}">
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition Width="Auto" />
                                <ColumnDefinition Width="*" />
                            </Grid.ColumnDefinitions>
                            <TextBlock Foreground="{DynamicResource LBFTabTextBrush}"
                               FontWeight="SemiBold"
                               Margin="{StaticResource LBFSmallThickness}" MaxWidth="300"
                               VerticalAlignment="Center"
                               Text="{Binding RelativeSource={RelativeSource AncestorType={x:Type TabItem} }, Path=Content.DataContext.TabHeader}"
                               ToolTipService.ToolTip="{Binding RelativeSource={RelativeSource AncestorType={x:Type TabItem} }, Path=Content.DataContext.TabToolTip}">
                                <TextBlock.ContextMenu >
                                    <ContextMenu Visibility="{Binding RelativeSource={RelativeSource AncestorType={x:Type TabItem}}, Path=Content.DataContext.CanClose,Converter={StaticResource VisibilityConverter}}">
                                        <MenuItem Header="Luk alle"/>
                                        <MenuItem Header="Luk alle, undtagen denne"/>
                                    </ContextMenu>
                                </TextBlock.ContextMenu>
                            </TextBlock>
                            <Button Width="15" Height="15"
                            Style="{StaticResource CloseButtonStyle}"
                            Visibility="{Binding RelativeSource={RelativeSource AncestorType={x:Type TabItem}}, Path=Content.DataContext.CanClose,Converter={StaticResource VisibilityConverter}}"
                            Grid.Column="1" IsHitTestVisible="True">
                                <i:Interaction.Triggers>
                                    <i:EventTrigger EventName="Click">
                                        <infrastructure:CloseTabbedViewAction />
                                    </i:EventTrigger>
                                </i:Interaction.Triggers>
                            </Button>
                        </Grid>
                    </Grid>
                </Grid>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsSelected" Value="True">
                        <Setter TargetName="ForegroundBorder" Property="Background" Value="White" />
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

我猜绑定失败是因为上下文菜单不在可视树中。我用snoop检查

Answer 1

你是对的，上下文菜单不是可视树的一部分。它们不继承与它们所属的控件相同的源进行绑定。处理这个问题的方法是绑定到ContextMenu本身的放置目标。所以试试这个:

<TextBlock.ContextMenu >
  <ContextMenu Visibility="{Binding PlacementTarget.DataContext.CanClose, RelativeSource={RelativeSource Self}}">
    <MenuItem Header="Luk alle"/>
    <MenuItem Header="Luk alle, undtagen denne"/>
  </ContextMenu>
</TextBlock.ContextMenu>