如何在Metro WinRT中显示多个PopupMenu？

Question

如何在Metro / WinRT（C＃）中显示多个PupupMenu，如下图所示？

这是我的C＃代码。

    private async void OnPointerPressed(object sender, Windows.UI.Xaml.Input.PointerRoutedEventArgs e)
    {
        PopupMenu menu1 = new PopupMenu();
        menu1.Commands.Add(new UICommand("menu1 A", (function) => { }));
        menu1.Commands.Add(new UICommand("menu1 B", (function) => { }));
        Task<IUICommand> task1 = menu1.ShowAsync(new Point(100, 100)).AsTask<IUICommand>();

        PopupMenu menu2 = new PopupMenu();
        menu2.Commands.Add(new UICommand("menu2 C", (function) => { }));
        menu2.Commands.Add(new UICommand("menu2 D", (function) => { }));
        Task<IUICommand> task2 = menu2.ShowAsync(new Point(200, 100)).AsTask<IUICommand>(); // A first chance exception of type 'System.InvalidOperationException' occurred in mscorlib.dll

        Task<IUICommand> task = await Task.WhenAny(task1, task2);

        if (task.Result != null)
        {
            await new MessageDialog(task.Result.Label).ShowAsync();
        }
    }

Answer 1

我不知道是否可以显示多个弹出菜单，但是您的代码通过在任务上调用Result来阻止UI线程。

请改为尝试：

private async void OnPointerPressed(object sender, Windows.UI.Xaml.Input.PointerRoutedEventArgs e)
{
    PopupMenu menu1 = new PopupMenu();
    menu1.Commands.Add(new UICommand("menu1 A", (function) => { }));
    menu1.Commands.Add(new UICommand("menu1 B", (function) => { }));
    Task<IUICommand> task1 = menu1.ShowAsync(new Point(100, 100)).AsTask<IUICommand>();

    PopupMenu menu2 = new PopupMenu();
    menu2.Commands.Add(new UICommand("menu2 C", (function) => { }));
    menu2.Commands.Add(new UICommand("menu2 D", (function) => { }));
    Task<IUICommand> task2 = menu2.ShowAsync(new Point(200, 100)).AsTask<IUICommand>(); // A first chance exception of type 'System.UnauthorizedAccessException' occurred in mscorlib.dll

    Task<IUICommand> task = await Task.WhenAny(task1, task2);

    var res = await task;
    if (res != null)
    {
        await new MessageDialog(res.Label).ShowAsync();
    }

    await Task.WaitAll(task1, task2); // just to await them all
}

Answer 2

你做不到。 WinRT不支持显示多个弹出窗口（它会告诉您一个例外）。对于PopupMenu，MessageBox以及更多内容都是如此。

你可能会创建一个看起来像双PopupMenu的自己的窗口，但我会建议不要这样做。