如何在WPF XAML中制作加载图形？

   <Storyboard x:Key="LoadingAnimation">
       <DoubleAnimation
            Storyboard.TargetName="Ellipse1"
            Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[3].(TranslateTransform.X)"
            From="0" To="100" Duration="0:0:1"
            AutoReverse="True" RepeatBehavior="Forever" />
       <DoubleAnimation
            Storyboard.TargetName="Ellipse2"
            Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[3].(TranslateTransform.X)"
            From="0" To="100" Duration="0:0:1"
            AutoReverse="True" RepeatBehavior="Forever" BeginTime="0:0:0.2" />
    </Storyboard>
</Window.Resources>

<Grid>
    <Ellipse
        Name="Ellipse1"
        Width="20" Height="20"
        Fill="Blue"
        RenderTransformOrigin="0.5,0.5">
        <Ellipse.RenderTransform>
           <TransformGroup>
               <ScaleTransform />
                <SkewTransform />
                <RotateTransform />
               <TranslateTransform />
            </TransformGroup>
        </Ellipse.RenderTransform>
    </Ellipse>
    <Ellipse
        Name="Ellipse2"
        Width="20" Height="20"
        Fill="Blue"
        RenderTransformOrigin="0.5,0.5">
        <Ellipse.RenderTransform>
           <TransformGroup>
               <ScaleTransform />
                <SkewTransform />
                <RotateTransform />
               <TranslateTransform />
            </TransformGroup>
        </Ellipse.RenderTransform>
    </Ellipse>
   <Button Content="开始加载动画" Click="Button_Click" />
</Grid>

private void Button_Click(object sender, RoutedEventArgs e)
{
    var animation = (Storyboard)FindResource("LoadingAnimation");
    animation.Begin();
}