WPF 数据触发动画效果

<Window.Resources>
        <Style  x:Key="ImageAnimationStyle" TargetType="Image">
            <Style.Triggers>
                <DataTrigger Binding="{Binding IsRotate}" Value="true">
                    <DataTrigger.EnterActions>
                        <BeginStoryboard x:Name="b">
                            <Storyboard>
                                <DoubleAnimation 
                                    Storyboard.TargetProperty="(Image.RenderTransform).(RotateTransform.Angle)"
                                    To="60" 
                                    RepeatBehavior="Forever"
                                    AutoReverse="True"
                                    Duration="0:0:0.5">
                                </DoubleAnimation>
                            </Storyboard>
                        </BeginStoryboard>
                    </DataTrigger.EnterActions>
                    <DataTrigger.ExitActions>
                        <StopStoryboard BeginStoryboardName="b"/>
                    </DataTrigger.ExitActions>
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>


    <Window.DataContext>
        <local:Datas/>
    </Window.DataContext>
    <Grid >
        <Grid.RowDefinitions>
            <RowDefinition Height="28*"/>
            <RowDefinition Height="407*"/>
        </Grid.RowDefinitions>
        
        <StackPanel Orientation="Horizontal">
            <Button Content="start" Width="100" Command="{Binding StartRotateCmd}"/>
            <Button Content="stop" Width="100" Command="{Binding StopRotateCmd}"/>

        </StackPanel>
        <Viewbox Grid.Row="1">
            <Image Style="{StaticResource ImageAnimationStyle}" Source="pack://application:,,,/通风风扇.png" Width="200" Margin="300,0,300,0" >
                <Image.RenderTransform>
                    <RotateTransform CenterX="100" CenterY="100"/>
                </Image.RenderTransform>
            </Image>
        </Viewbox>
        
    </Grid>