wpf 旋转效果

<Grid>
<Grid.Triggers>
<EventTrigger RoutedEvent="Page.Loaded">
<BeginStoryboard>
<Storyboard RepeatBehavior="Forever" >
<DoubleAnimation Storyboard.TargetName="borderForm" Storyboard.TargetProperty="Angle" By="360" Duration="0:0:1" />
<DoubleAnimation Storyboard.TargetName="border1" Storyboard.TargetProperty="Opacity" From="0.0" To="1.0" Duration="0:0:1" />
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Grid.Triggers>
<Border x:Name="border1" Height="90" Width="90" BorderThickness="1,0,0,0" BorderBrush="Red" CornerRadius="90">
<Border.RenderTransform>
<RotateTransform x:Name="borderForm" Angle="0" CenterX="45" CenterY="45"/>
</Border.RenderTransform>
</Border>
</Grid>