WPF DispatcherFrame 魔法 - 它是如何以及为什么起作用的? [英] WPF DispatcherFrame magic - how and why this works?

问题描述

我试图在 WPF 中制作一些动画，并在动画完成时运行一些其他操作.

I was trying to animate some stuff in WPF and run some other operations when animation finishes.

另外，想避免动画完成回调机制，所以，我想出了一个解决方案，如下代码所示:

Also, wanted to avoid animation finish callback mechanism, so, I came up with a solution illustrated in the code below:

// Start one second of animation
...

// Pause for one second
Wait(this.Dispatcher, 1000);

// Continue and do some other stuff
...

现在，有趣的部分是 Wait 方法，它神奇地使我的代码中的阻塞暂停但动画和 UI 保持正常、响应:

Now, the interesting part is Wait method which magically makes blocking pause in my code but the animation and UI stays normal, responsive:

    public static void Wait(Dispatcher Dispatcher, int Milliseconds)
    {
        var Frame = new DispatcherFrame();
        ThreadPool.QueueUserWorkItem(State =>
        {
            Thread.Sleep(Milliseconds);
            Frame.Continue = false;
        });
        Dispatcher.PushFrame(Frame);
    }

我已经阅读了关于 DispatcherFrame 的文档和几篇文章，但我仍然无法弄清楚幕后真正发生了什么，我需要一些关于如何使用 进行构造的说明PushFrame 确实有效.

I have read a documentation and a few articles about DispatcherFrame but I am still unable to figure out what is really happening under the hood, and I need some clarification about how this construction with PushFrame really works.

推荐答案

来自 MSDN:

推送框架

进入执行循环.

只要其 Continue 属性为 true，该循环(即 DispatcherFrame)就会执行.

That loop (i.e. the DispatcherFrame) executes as long as its Continue property is true.

一旦 Continue 属性变为 false，循环/帧就会退出，并且 Dispatcher 返回到它在调用 PushFrame 之前执行的循环/帧.

As soon as the Continue property goes to false, the loop/frame is exited and the Dispatcher returns to the loop/frame that it executed before you called PushFrame.

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