等待XAML布局完成 [英] Waiting for XAML layout to complete

问题描述

我正在对页面进行一些更改(通过添加/删除控件)，并且仅在布局确定(所有元素都已测量和排列等)之后，我才继续执行我的代码.

I am making some changes to a page (by adding/removing controls) and I want to continue with my code only when the layout is settled (all elements measured and arranged etc).

我该怎么做?是否有一些我可以等待的任务，当布局完成后会启动?

How do I do this? Is there some Task I can await on that will fire when layout is complete?

(现在使用Yields和其他技巧，但它们都使我感到肮脏)

(Right now using Yields and other tricks, but they all make me feel dirty)

推荐答案

您可以使用 TaskCompletionSource< T> 围绕任何事件构建 Task .

You can build a Task around any event by using TaskCompletionSource<T>.

在您的情况下，听起来像 UIElement.LayoutUpdated 可能是您想要的事件(对此不完全确定-WPF布局细节不是我的强项).

In your case, it sounds like UIElement.LayoutUpdated may be the event you want (not entirely sure about that - WPF layout details are not my strong point).

这是一个例子:

public static Task LayoutUpdatedAsync(this UIElement element)
{
  var tcs = new TaskCompletionSource<object>();
  EventHandler handler = (s, e) =>
  {
    element.LayoutUpdated -= handler;
    tcs.SetCompleted(null);
  };
  element.LayoutUpdated += handler;
  return tcs.Task;
}

然后，您可以使用此方法等待该事件的下一个实例:

Then you can use this method to await the next instance of that event:

await myUiElement.LayoutUpdatedAsync();

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