c# - 暂停/恢复 WPF Storyboard

Question

我已经阅读了十几篇关于如何暂停和恢复 WPF Storyboard 的文章，但我就是无法让它发挥作用。这是我的问题:我有一个带有 Storyboard的用户控件。 Storyboard看起来像这样:

 <UserControl.Resources>
    <Storyboard x:Key="TheStoryboard" RepeatBehavior="Forever">
      <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[2].(RotateTransform.Angle)" Storyboard.TargetName="Arc1">
        <EasingDoubleKeyFrame KeyTime="0" Value="0"/>
        <EasingDoubleKeyFrame KeyTime="0:0:2" Value="90"/>
        <EasingDoubleKeyFrame KeyTime="0:0:4" Value="180"/>
        <EasingDoubleKeyFrame KeyTime="0:0:6" Value="270"/>
        <EasingDoubleKeyFrame KeyTime="0:0:8" Value="360"/>
      </DoubleAnimationUsingKeyFrames>
   </Storyboard>
  </UserControl.Resources>

很简单，它让方舟永远旋转。现在在后面的代码中，我有一个依赖属性，它绑定(bind)到一个 bool 值，指示动画何时应该旋转或停止。这会触发一个方法，理论上应该暂停或恢复动画。它看起来像这样:

private void SetStoryBoardActivity(bool play)
    {
      var storyboard = (Storyboard)this.Resources["TheStoryboard"];
      if (play)
      {
        storyboard.Resume();
      }
      else
      {
        storyboard.Pause();       
      }
    }

执行路径按预期进入方法，但是调用Pause()时动画没有停止；我试过了

    storyboard.Stop();
    storyboard.Stop(this);
    storyboard.Stop(this.Arc1);
    storyboard.Freeze();
    storyboard.Pause();
    storyboard.Pause(this);
    storyboard.Pause(this.Arc1);

但似乎没有任何效果。有谁知道我做错了什么？

Answer 1

所以在我的案例中答案似乎是视觉状态。我设法通过以下方式完成这项工作:我将 Storyboard移动到这样的可视化状态管理器:

<Grid x:Name="LayoutRoot">  
 <VisualStateManager.VisualStateGroups>
  <VisualStateGroup x:Name="Animation">
    <VisualState x:Name="On">
     <Storyboard  RepeatBehavior="Forever">
       <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[2].(RotateTransform.Angle)" Storyboard.TargetName="Arc1">
       <EasingDoubleKeyFrame KeyTime="0" Value="0"/>
       <EasingDoubleKeyFrame KeyTime="0:0:2" Value="90"/>
       <EasingDoubleKeyFrame KeyTime="0:0:4" Value="180"/>
       <EasingDoubleKeyFrame KeyTime="0:0:6" Value="270"/>
       <EasingDoubleKeyFrame KeyTime="0:0:8" Value="360"/>
      </DoubleAnimationUsingKeyFrames>          
     </Storyboard>
    </VisualState>
   <VisualState x:Name="Off"/>
  </VisualStateGroup>
 </VisualStateManager.VisualStateGroups>    
 <ed:Arc x:Name="Arc1" ArcThickness="15" ArcThicknessUnit="Pixel" StartAngle="30" EndAngle="150" Fill="#C0375E77" HorizontalAlignment="Center" Height="200" Width="200" Margin="0,0,0,0" Stretch="None" Stroke="#FF204050" StrokeThickness="2" VerticalAlignment="Center" RenderTransformOrigin="0.5,0.5" >
  <ed:Arc.RenderTransform>
    <TransformGroup>
      <ScaleTransform/>
      <SkewTransform/>
      <RotateTransform/>
      <TranslateTransform/>
    </TransformGroup>
   </ed:Arc.RenderTransform>
  </ed:Arc>
 </Grid>

请注意，视觉状态管理器并未放置在控件的资源中，而是放置在控件的主容器中。ed 在哪里:

xmlns:ed="http://schemas.microsoft.com/expression/2010/drawing"

SetStoryBoardActivity 方法变为:

 private void SetStoryBoardActivity()
 {
   VisualStateManager.GoToState(this, this.AnimationActive ? "On" : "Off", true);
 }

其中this.AnimationActive是我问题中提到的依赖属性。