如果在處理后調用Stop（），則WPF StoryBoard無法開始

Question

我有一個包含圖像的按鈕，我希望圖像在執行某些代碼時旋轉，然后在此處理結束時停止。

如果開始情節提要，我的代碼幾乎可以工作，但是當我添加sb.Stop（）行時，動畫永遠不會開始。

這是我的代碼：

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();
    }

我被卡住了。

Answer 1

我有一個適合我的解決方案。

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);
    }

整個示例代碼：

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，我想在這里解釋您的問題。 當您使用UI-Thread進行“工作”時，它無法更新您的UI，盡管無法動畫化旋轉，但在“開始”和停止動畫之間使用“工作”完成旋轉時，最終會有時間要更新用戶界面，請致電以停止動畫制作。 這導致不顯示任何動畫。 您需要將工作放在不同的線程中，以防止發生這種情況。

希望能有所幫助。