[英]How to raise ContextMenuOpening event when opening context menu programmatically
當我使用<control>.ContextMenu.IsOpen = true
打開上下文菜單時,上下文菜單變得可見,但不會觸發打開或關閉事件。
當我以編程方式打開上下文菜單時,如何確保引發ContextMenuOpening
和ContextMenuClosing
事件?
看下面的XAML
<Button Name="ContextMenuButton"
Content="Click me!"
Click="ContextMenuButton_Click"
ContextMenuOpening="ContextMenuButton_OnContextMenuOpening"
ContextMenuClosing="ContextMenuButton_OnContextMenuClosing">
<Button.ContextMenu>
<ContextMenu>
<MenuItem Header="First element" />
<MenuItem Header="Second element" />
</ContextMenu>
</Button.ContextMenu>
</Button>
以及以下代碼隱藏
public MainWindow() // Constructor
{
InitializeComponent();
ContextMenuButton.ContextMenuOpening += (sender, args) => Debug.Print("Opening #2");
ContextMenuButton.ContextMenuClosing += (sender, args) => Debug.Print("Closing #2");
}
private void ContextMenuButton_Click(object sender, RoutedEventArgs e)
{
Button button = (sender as Button);
button.ContextMenu.IsOpen = true; // How should I open the ContextMenu?
}
private void ContextMenuButton_OnContextMenuOpening(object sender, ContextMenuEventArgs e)
{
Debug.Print("Opening #1");
}
private void ContextMenuButton_OnContextMenuClosing(object sender, ContextMenuEventArgs e)
{
Debug.Print("Closing #1");
}
上下文菜單正在打開。
輸出是:
Opening #1
Opening #2
Closing #1
Closing #2
上下文菜單正在打開。
輸出是:
<Nothing>
問題是您在 Button 的 ContextMenuOpening 上附加了事件,並且由於您手動調用了 ContextMenu,因此事件沒有觸發
所以為了讓事件附加來自 ContextMenu 的 Opened 和 Closed 事件
public MainWindow() // Constructor
{
InitializeComponent();
ContextMenuButton.ContextMenu.Opened += (sender, args) => Debug.Print("Opening #2");
ContextMenuButton.ContextMenu.Closed += (sender, args) => Debug.Print("Closing #2");
}
xml
<Button Name="ContextMenuButton"
Content="Click me!"
Click="ContextMenuButton_Click" >
<Button.ContextMenu>
<ContextMenu Opened="ContextMenuButton_OnContextMenuOpening" Closed="ContextMenuButton_OnContextMenuClosing">
<MenuItem Header="First element" />
<MenuItem Header="Second element" />
</ContextMenu>
</Button.ContextMenu>
</Button>
事件,ContextMenuEventArgs 更改為 RoutedEventArgs
private void ContextMenuButton_OnContextMenuOpening(object sender, RoutedEventArgs e)
{
Debug.Print("Opening #1");
}
private void ContextMenuButton_OnContextMenuClosing(object sender, RoutedEventArgs e)
{
Debug.Print("Closing #1");
}
按鈕點擊保持不變。
這應該可以解決您的問題
Opened 和 Opening 事件之間存在差異。 通常 Opening 事件用於在菜單顯示之前動態構建菜單。 在這種情況下,上述解決方案將不起作用。
`
// Raise Context menu Opening Event
var args = CreateInstance<ContextMenuEventArgs>(element, true);
args.RoutedEvent = FrameworkElement.ContextMenuOpeningEvent;
element.RaiseEvent(args);
contextMenu.IsOpen = true;
`
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