WPF实现左右移动（晃动）动画效果

<Canvas>    <Grid Width="200" Height="100" Background="MediumAquamarine" Name="GroupboxArea" Canvas.Left="100" Canvas.Top="200"/>    <Button Content="Button" Height="25" Width="78" Click="Button_Click"/></Canvas>

 private void Button_Click(object sender, RoutedEventArgs e)    {      DoubleAnimation DAnimation = new DoubleAnimation();      DAnimation.From = 100;//起点      DAnimation.To = 280;//终点      DAnimation.Duration = new Duration(TimeSpan.FromSeconds(0.5));//时间      Storyboard.SetTarget(DAnimation, GroupboxArea);      Storyboard.SetTargetProperty(DAnimation, new PropertyPath(Canvas.LeftProperty));      Storyboard story = new Storyboard();      story.Completed += new EventHandler(story_Completed);//完成后要做的事      //story.RepeatBehavior = RepeatBehavior.Forever;//无限次循环，需要的自己加上      story.Children.Add(DAnimation);      story.Begin();    }    void story_Completed(object sender, EventArgs e)    {      DoubleAnimation DAnimation = new DoubleAnimation();      DAnimation.From = 280;//起点      DAnimation.To = 100;//终点      DAnimation.Duration = new Duration(TimeSpan.FromSeconds(0.5));//时间      Storyboard.SetTarget(DAnimation, GroupboxArea);      Storyboard.SetTargetProperty(DAnimation, new PropertyPath(Canvas.LeftProperty));      Storyboard story = new Storyboard();      story.Completed += new EventHandler(storyCompleted);//完成后要做的事      //story.RepeatBehavior = RepeatBehavior.Forever;//无限次循环，需要的自己加上      story.Children.Add(DAnimation);      story.Begin();    }    void storyCompleted(object sender, EventArgs e)    {      DoubleAnimation DAnimation = new DoubleAnimation();      DAnimation.From = 100;//起点      DAnimation.To = 200;//终点      DAnimation.Duration = new Duration(TimeSpan.FromSeconds(0.5));//时间      Storyboard.SetTarget(DAnimation, GroupboxArea);      Storyboard.SetTargetProperty(DAnimation, new PropertyPath(Canvas.LeftProperty));      Storyboard story = new Storyboard();      //story.Completed += new EventHandler(storyCompleted);//完成后要做的事      //story.RepeatBehavior = RepeatBehavior.Forever;//无限次循环，需要的自己加上      story.Children.Add(DAnimation);      story.Begin();    }