如何停止应用于 ListBoxItem 的情节提要动画？

Question

在我的聊天应用程序中，我有一个用户列表框，其中发送消息的任何人都在其中发送消息，如果他的聊天窗口未在用户侧打开，则他的名字开始在列表框中闪烁以通知用户传入消息。 如果用户选择该发送者，我将删除动画。但动画仅针对最后应用动画的元素停止。

以下是我用于将动画应用于 listboxItem 的代码，

   private void BlinkSenderUsername(int index, string userRole)
    {
        blinkAnimation = new DoubleAnimationUsingKeyFrames();
        blinkAnimation.KeyFrames.Add(new DiscreteDoubleKeyFrame(1, KeyTime.FromTimeSpan(TimeSpan.FromMilliseconds(0))));
        blinkAnimation.KeyFrames.Add(new DiscreteDoubleKeyFrame(0, KeyTime.FromTimeSpan(TimeSpan.FromMilliseconds(250))));
        ListBoxItem target = new ListBoxItem();

    target = OnlineUserList.ItemContainerGenerator.ContainerFromIndex(index) as ListBoxItem;
        OnlineUserList.ScrollIntoView(target);

        blinkStoryboard = new Storyboard
        {
            Duration = TimeSpan.FromMilliseconds(900),
            RepeatBehavior = RepeatBehavior.Forever,
        };

        Storyboard.SetTarget(blinkAnimation, target);
        Storyboard.SetTargetProperty(blinkAnimation, new PropertyPath(OpacityProperty));

        blinkStoryboard.Children.Add(blinkAnimation);
        blinkStoryboard.Begin(target, true);
    }

和列表框的选择更改事件（在选择时停止动画）：

   private void OnlineUserListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
    ListBoxItem listBoxItem = OnlineUserList.ItemContainerGenerator.ContainerFromItem(OnlineUserList.SelectedItem) as ListBoxItem;
                if (listBoxItem != null && listBoxItem.HasAnimatedProperties)
                {
                    blinkStoryboard.Stop(listBoxItem);
                }

}

谁能建议，我做错了什么？

编辑（根据 Jai 的回答）：-

    static void MyClassStaticConstructor()
    {
        BlinkAnimation = new DoubleAnimationUsingKeyFrames();
        BlinkAnimation.KeyFrames.Add(new DiscreteDoubleKeyFrame(1, KeyTime.FromTimeSpan(TimeSpan.FromMilliseconds(0))));
        BlinkAnimation.KeyFrames.Add(new DiscreteDoubleKeyFrame(0, KeyTime.FromTimeSpan(TimeSpan.FromMilliseconds(250))));

        BlinkStoryboard = new Storyboard
        {
            Duration = TimeSpan.FromMilliseconds(900),
            RepeatBehavior = RepeatBehavior.Forever,
        };

        BlinkStoryboard.Children.Add(BlinkAnimation);
    }

    private void BlinkSenderUsername(int index, string userRole)
    {
        // There is no need to instantiate a ListBoxItem
        //ListBoxItem target = new ListBoxItem();
          ListBoxItem target = OnlineUserList.ItemContainerGenerator.ContainerFromIndex(index) as ListBoxItem;

        if (target == null) return;
        MyClassStaticConstructor();
        Storyboard.SetTarget(BlinkAnimation, target);
        Storyboard.SetTargetProperty(BlinkAnimation, new PropertyPath(OpacityProperty));

        BlinkStoryboard.Begin(target, true);
    }

并在列表框的 selectionchanged 事件中：

    private void OnlineUserListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
ListBoxItem listBoxItem = OnlineUserList.ItemContainerGenerator.ContainerFromItem(OnlineUserList.SelectedItem) as ListBoxItem;
            if (listBoxItem != null && listBoxItem.HasAnimatedProperties)
            {
                BlinkStoryboard.Stop(listBoxItem);
            }} 

Answer 1

问题在于，对于每个ListBoxItem，您正在创建一个Storyboard 和一个Animation 对象。情节提要和动画对象都保存到单个全局字段中。当您设置多个此类动画时，您的全局字段将具有仅最后添加的动画/故事板的引用。

将实现更改为：

private static readonly DoubleAnimationUsingKeyFrames BlinkAnimation;
private static readonly Storyboard BlinkStoryboard;

static MyClassStaticConstructor()
{
    BlinkAnimation = new DoubleAnimationUsingKeyFrames();
    BlinkAnimation.KeyFrames.Add(new DiscreteDoubleKeyFrame(1, KeyTime.FromTimeSpan(TimeSpan.FromMilliseconds(0))));
    BlinkAnimation.KeyFrames.Add(new DiscreteDoubleKeyFrame(0, KeyTime.FromTimeSpan(TimeSpan.FromMilliseconds(250))));

    BlinkStoryboard = new Storyboard
    {
        Duration = TimeSpan.FromMilliseconds(900),
        RepeatBehavior = RepeatBehavior.Forever,
    };

    BlinkStoryboard.Children.Add(blinkAnimation);
}

private void BlinkSenderUsername(int index, string userRole)
{
    // There is no need to instantiate a ListBoxItem
    //ListBoxItem target = new ListBoxItem();
    ListBoxItem target = OnlineUserList.ItemContainerGenerator.ContainerFromIndex(index) as ListBoxItem;

    if (target == null) return; // Just make sure we managed to get a ListBoxItem instance
    OnlineUserList.ScrollIntoView(target);

    Storyboard.SetTarget(BlinkAnimation, target);
    Storyboard.SetTargetProperty(BlinkAnimation, new PropertyPath(OpacityProperty));

    BlinkStoryboard.Begin(target, true);
}

动画和故事板对象是可重复使用的 - 因此如果多个控件需要相同的动画，它们可以使用相同的动画/故事板实例。你只需要实例化一次。在我的回答中，我已将它们设为静态，但您可以选择不将它们设为静态。