Question

我的应用程序中有一个类似于此示例的RibbonApplicationMenu：

<RibbonApplicationMenu>
    <RibbonApplicationMenuItem Header="Open Project..." Command="{Binding OpenProjectCommand}" />
    <RibbonApplicationMenuItem Header="Save Project..." Command="{Binding SaveProjectCommand}" />
    <RibbonApplicationMenuItem Header="Exit" Command="{Binding CloseWindowCommand}" CommandParameter="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type RibbonWindow}}}" />
    <RibbonApplicationMenu.FooterPaneContent>
        <RibbonButton Label="Exit" Command="{Binding CloseWindowCommand}" CommandParameter="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type RibbonWindow}}}" />
    </RibbonApplicationMenu.FooterPaneContent>
</RibbonApplicationMenu>

private void CloseWindow (Object parameter)
{
    ((Window) parameter).Close();
}

在示例中，有一个RibbonApplicationMenuItem和RibbonButton项绑定到同一个命令并传递了相同的参数。该命令执行CloseWindow（）函数。我发现很奇怪的是，当单击RibbonApplicationMenuItem时，该函数的参数是指向RibbonWindow的指针。但是，单击RibbonButton时，函数的参数为null。

为什么行为会有所不同？

Answer 1

将FooterPaneContent设置为另一个控件（RibbonButton）会弄乱逻辑树，这就是RelativeAncestor不起作用的原因。

换句话说，即使您绑定到按钮本身，使用LogicalTreeHelper遍历也不起作用（VisualTreeHelper也不起作用，因为窗格是PopUp并且生活在另一个可视树中）：

<r:RibbonApplicationMenu.FooterPaneContent>
    <r:RibbonButton Label="Exit" Command="{Binding CloseWindowCommand}" CommandParameter="{Binding RelativeSource={RelativeSource Self}}" />
</r:RibbonApplicationMenu.FooterPaneContent>

private void CloseWindow(object parameter)
{
    RibbonButton _button = (RibbonButton)parameter;

    // _appMenu will be null
    DependencyObject _appMenu = LogicalTreeHelper.GetParent(_button);
}

所以，你的选择是：

绑定到self并使用_button.Ribbon属性获取Ribbon并遍历逻辑树以获取RibbonWindow。
设置ContentTemplate而不是Content。小心传播DataContext虽然。

<r:RibbonApplicationMenu.FooterPaneContentTemplate>
    <DataTemplate>
        <r:RibbonButton Label="Exit" DataContext="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type r:RibbonApplicationMenu}}, Path=DataContext}" Command="{Binding Path=CloseWindowCommand}" CommandParameter="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type r:RibbonWindow}}}" />
    </DataTemplate>
</r:RibbonApplicationMenu.FooterPaneContentTemplate>

   private void CloseWindow(object parameter)
   {
        ((Window)parameter).Close();
   }

RibbonApplicationMenu命令中的不同行为

1 个答案: