如果在处理后调用Stop()，则WPF StoryBoard不会开始 [英] WPF StoryBoard doesn't begin if Stop() is called after processing

问题描述

我有一个包含图像的按钮，我希望图像在执行某些代码的同时旋转，然后在此处理结束时停止.

I have a button containing an image, and I want that image rotates while some code is executed, then stop at the end of this processing.

如果我开始情节提要，我的代码几乎可以工作，但是当我添加sb.Stop()行时，动画永远不会开始.

My code almost works if I begin the storyboard, but when I add the line sb.Stop(), the animation never begins.

这是我的代码:

private void refreshPostIt(int postItIndex)
    {
        Button btn = // Button to rotate

        Storyboard sb = new Storyboard();
        DoubleAnimation rotate = new DoubleAnimation();
        rotate.From = 0;
        rotate.To = 360;
        rotate.RepeatBehavior = RepeatBehavior.Forever;

        RotateTransform rt = new RotateTransform();
        btn.RenderTransformOrigin = new Point(0.5, 0.5);
        btn.RenderTransform = rt;
        Storyboard.SetTarget(rotate, btn);
        Storyboard.SetTargetName(rotate, btn.Name);
        Storyboard.SetTargetProperty(rotate, new PropertyPath("(UIElement.RenderTransform).(RotateTransform.Angle)"));
        sb.Children.Add(rotate);
        sb.Begin(this, true);

        // Some code which can take several seconds

        sb.Stop();
    }

我被困住了.

推荐答案

我有一个适合我的解决方案.

I have a solution that works for me.

private void refreshPostIt()
    {
        // Button btn; is defined somewhere else

        Storyboard sb = new Storyboard();
        DoubleAnimation rotate = new DoubleAnimation();
        rotate.From = 0;
        rotate.To = 360;
        rotate.RepeatBehavior = RepeatBehavior.Forever;

        RotateTransform rt = new RotateTransform();
        btn.RenderTransformOrigin = new Point(0.5, 0.5);
        btn.RenderTransform = rt;
        Storyboard.SetTarget(rotate, btn);
        Storyboard.SetTargetName(rotate, btn.Name);
        Storyboard.SetTargetProperty(rotate, new PropertyPath("(UIElement.RenderTransform).(RotateTransform.Angle)"));
        sb.Children.Add(rotate);
        sb.Begin(btn, true);

            // Do your stuff here (Not in the UI Thread)
            // Maybe use a semaphore to lock the sb.Stop(btn)

        sb.Stop(btn);
    }

整个示例代码:

public partial class Window1 : Window
{
    Button btn;
    Storyboard sb;
    public Window1()
    {
        btn = new Button();
        InitializeComponent();
        this.grid.Children.Add(btn);
        refreshPostIt();
    }

    private void refreshPostIt()
    {
        // Button btn; is defined somewhere else

        sb = new Storyboard();
        DoubleAnimation rotate = new DoubleAnimation();
        rotate.From = 0;
        rotate.To = 360;
        rotate.RepeatBehavior = RepeatBehavior.Forever;

        RotateTransform rt = new RotateTransform();
        btn.RenderTransformOrigin = new Point(0.5, 0.5);
        btn.RenderTransform = rt;
        Storyboard.SetTarget(rotate, btn);
        Storyboard.SetTargetName(rotate, btn.Name);
        Storyboard.SetTargetProperty(rotate, new PropertyPath("(UIElement.RenderTransform).(RotateTransform.Angle)"));
        sb.Children.Add(rotate);
        sb.Begin(btn, true);

        BackgroundWorker asd = new BackgroundWorker();
        asd.DoWork += new DoWorkEventHandler(asd_DoWork);
        asd.RunWorkerCompleted += new RunWorkerCompletedEventHandler(asd_RunWorkerCompleted);
        asd.RunWorkerAsync();

    }

    void asd_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        if (sb != null)
        {
            sb.Stop(btn);
        }
    }

    void asd_DoWork(object sender, DoWorkEventArgs e)
    {
        Thread.Sleep(2000);
    }
}

好的，我想在这里解释您的问题.当您使用UI-Thread进行工作"时，它无法更新您的UI，尽管无法动画化旋转，但在动画"完成后，在开始和停止动画之间进行旋转，最终会有时间要更新用户界面，请致电以停止动画制作.这导致不显示任何动画.您需要将工作放在不同的线程中，以防止发生这种情况.

Ok, I want to explain what I think is your problem here. When you use the UI-Thread to do your "work" it can't update your UI and though won't animate the rotating, when its done with your "work", between starting and stopping the animation, and finally would have time to update the UI, you call to stop animating. That leads to not showing any animation. You need to put your work in a different thread to prevent this from happening.

希望有帮助.

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