我有一个由6个不同标签共享的上下文菜单，如何判断哪个标签正在使用上下文菜单的当前实例？

Question

Here is the xaml for the contextMenu:

    <Window.Resources>
    <ContextMenu x:Key="IBContextMenu" x:Shared="true" Name="IBContextMenu1">
        <MenuItem Header="Edit" Click="ibEdit_Click" AllowDrop="False" />
        <MenuItem Header="Clear" Click="ibClear_Click"/>
    </ContextMenu>
</Window.Resources>

Both the edit and clear items' methods need to know which label to act upon. How can I do this?

Answer 1

I think you are looking for PlacementTarget : http://msdn.microsoft.com/en-us/library/system.windows.controls.contextmenu.placementtarget.aspx

If you switch over to a Command-pattern, you can actually get this via Binding and pass it along as the CommandParameter...

Answer 2

Here's an answer I came up with. I don't really like it because it's a bit hack-ish, but it works. The idea is that you make your labels listen to the MouseRightButtonUp event, which is fired when the user releases the right mouse button after clicking to open the context menu. In the event handler, you set a private Label variable to the label that the user just right-clicked. Then, in your MenuItem click handler, you can access that private Label variable. Note that all the labels you want to do this must use the same event handler for MouseRightButtonUp.

For example:

<Window.Resources>
    <ContextMenu x:Key="MyMenu">
        <MenuItem Header="Edit" Click="Edit_Click"/>
        <MenuItem Header="Clear" Click="Clear_Click"/>
    </ContextMenu>
</Window.Resources>
<StackPanel>
    <Label ContextMenu="{StaticResource MyMenu}" 
           MouseRightButtonUp="Label_MouseRightButtonUp">Some text</Label>
    <Label ContextMenu="{StaticResource MyMenu}" 
           MouseRightButtonUp="Label_MouseRightButtonUp">Some junk</Label>
    <Label ContextMenu="{StaticResource MyMenu}" 
           MouseRightButtonUp="Label_MouseRightButtonUp">Some stuff</Label>
    <Label ContextMenu="{StaticResource MyMenu}"
           MouseRightButtonUp="Label_MouseRightButtonUp">Some 0000</Label>
</StackPanel>

Code behind:

private void Edit_Click(object sender, RoutedEventArgs e)
{
    if (clickedLabel != null)
    {
        MessageBox.Show(clickedLabel.Content.ToString());
    }
}

private void Clear_Click(object sender, RoutedEventArgs e)
{
    if (clickedLabel != null)
    {
        MessageBox.Show(clickedLabel.Content.ToString());
    }
}

private Label clickedLabel;
private void Label_MouseRightButtonUp(object sender, MouseButtonEventArgs e)
{
    clickedLabel = (Label)sender;
}

Answer 3

Try to set a DataContext to the Labels, for example

And in the Click event just check the ((FrameworkElement)sender).DataContext for FIRST/SECOND etc. Let us know if that works.