鼠標離開時關閉上下文菜單

Question

簡單問題 - 當鼠標光標離開ContextMenu時，MouseLeave事件不會被調用，爲什麼會這樣？ 我想在鼠標光標離開時關閉ContextMenu。 這裏是小樣本：

<Button Content="Right-click me!" VerticalAlignment="Center" HorizontalAlignment="Center"> 
     <Button.ContextMenu> 
      <ContextMenu MouseLeave="ContextMenu_MouseLeave"> 
       <MenuItem Header="Menu item 1" /> 
       <MenuItem Header="Menu item 2" /> 
       <Separator /> 
       <MenuItem Header="Menu item 3" /> 
      </ContextMenu> 
     </Button.ContextMenu> 
    </Button> 

Answer 1

你可以處理MouseLeave事件爲ContextMenu的內部Border元素。

處理的Loaded事件ContextMenu本身，發現在視覺樹Border元素和掛鉤的事件處理程序的MouseLeave事件：

<Button Content="Right-click me!" VerticalAlignment="Center" HorizontalAlignment="Center"> 
    <Button.ContextMenu> 
     <ContextMenu Loaded="ContextMenu_Loaded"> 
      <MenuItem Header="Menu item 1" /> 
      <MenuItem Header="Menu item 2" /> 
      <Separator /> 
      <MenuItem Header="Menu item 3" /> 
     </ContextMenu> 
    </Button.ContextMenu> 
</Button> 

---

private void ContextMenu_Loaded(object sender, RoutedEventArgs e) 
{ 
    ContextMenu cm = sender as ContextMenu; 
    Border border = GetChildOfType<Border>(cm); 
    border.MouseLeave += Border_MouseLeave; 
} 

private void Border_MouseLeave(object sender, MouseEventArgs e) 
{ 
    //do something here... 
} 

private static T GetChildOfType<T>(DependencyObject depObj) where T : DependencyObject 
{ 
    if (depObj == null) 
     return null; 

    for (int i = 0; i < VisualTreeHelper.GetChildrenCount(depObj); i++) 
    { 
     var child = VisualTreeHelper.GetChild(depObj, i); 

     var result = (child as T) ?? GetChildOfType<T>(child); 
     if (result != null) 
      return result; 
    } 
    return null; 
}