C＃WPF上下文菜单项单击事件返回null [英] C# WPF Context menu item click event returns null

问题描述

我正在使用WPF和C＃。我有一个按钮网格，并且为每个按钮（如果右键单击）分配了一个上下文菜单。右键单击按钮可以正常工作，并显示上下文菜单，但是单击菜单项将为空发送者。有什么事吗以下是嵌入到Windows XAML代码中的相关代码：

I'm using WPF with C#. I have a grid of buttons and I've assigned a context menu to each button if it's right-clicked. Right-clicking the buttons works fine and the context menu shows up but clicking the menu items gives a null sender. What could be wrong? Here is the relevant code embedded into the Window XAML code:

 <Window.Resources>
    <ContextMenu x:Key="cmButton">
        <MenuItem Header="Copy" Click="Copy_Click" />
        <MenuItem Header="Cut" />
        <Separator />
        <MenuItem Header="Paste" Click="Paste_Click" />
    </ContextMenu>
 </Window.Resources>

这是相关的C＃代码：

public void WarpHeadCell_RightClick(DraftWindow w, Button b)
    {
        ContextMenu cm = w.FindResource("cmButton") as ContextMenu;
        cm.PlacementTarget = b;
        cm.IsOpen = true;         
    } 

 private void Copy_Click(object sender, RoutedEventArgs e)
   {
       MenuItem mi = e.OriginalSource as System.Windows.Controls.MenuItem;
       ContextMenu cm = mi.ContextMenu;
       Button b = (Button)cm.PlacementTarget;   
   }

mi始终为null，有人知道吗？

mi is always null, does anybody have a clue?

推荐答案

我看不出mi会为null的任何原因，但是您还没有包含所有内容，所以我走到这里，猜测mi.ContextMenu是您遇到问题的地方。菜单项本身没有ContextMenu，但确实具有Parent属性，它是它所属的ContextMenu，可能正是您要查找的内容。

I don't see any reason why mi would be null, but you haven't included everything, so I'm going out on a limb here and guessing that mi.ContextMenu is where you are running into a problem. The menu item itself doesn't have a ContextMenu, but it does have a Parent property, which is the ContextMenu it belongs to and is probably what you are looking for.

private void Copy_Click(object sender, RoutedEventArgs e)
{
    MenuItem mi = sender as MenuItem;
    ContextMenu cm = mi.Parent as ContextMenu;
    Button b = cm.PlacementTarget as Button;
}

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