問題將在代碼中使用故事板動畫

Question

我有一個Canvas名爲Marker的Ellipse對象：

<!-- Boilerplate --> 
<Window x:Class="WpfApplication6.MainWindow" 
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
     xmlns:WpfApplication6="clr-namespace:WpfApplication6" 
     Title="MainWindow" Height="350" Width="525" 
     SnapsToDevicePixels="True"> 
    <Grid> 
    <Canvas x:Name="DrawingCanvas"> 
     <!-- ##### Item of interest, below ##### --> 
     <Ellipse x:Name="Marker" Canvas.Left="200" Canvas.Top="100" 
       Width="25" Height="25" Stroke="Black" Fill="#E0E000"> 
     <Ellipse.Effect> 
      <BlurEffect x:Name="MarkerBlurEffect" Radius="0.0" /> 
     </Ellipse.Effect> 
     </Ellipse> 
    </Canvas> 
    </Grid> 
</Window> 

我試圖以編程方式給Marker橢圓模糊動畫：

DoubleAnimation blurEffectAnimation=new DoubleAnimation 
    { 
    From=0, 
    To=10, 
    Duration=TimeSpan.FromSeconds(2.0) 
    }; 

    // If I uncomment the line below, the blur effect animation works perfectly 
    //Marker.Effect.BeginAnimation(BlurEffect.RadiusProperty, blurEffectAnimation); 

    // If I do it using the storyboard code below, the animation has no effect 
    Storyboard.SetTarget(blurEffectAnimation, Marker.Effect); 
    Storyboard.SetTargetProperty(blurEffectAnimation, 
           new PropertyPath(BlurEffect.RadiusProperty)); 

    Storyboard sb=new Storyboard(); 

    sb.Children.Add(blurEffectAnimation); 
    sb.Begin(); 

有趣的是，如果我通過名稱註冊效果並在故事板中使用該名稱，效果將再次開始工作：

// Register the MarketBlurEffect (as it's named in the XAML) effect by name 
    // with the FrameworkElement being animated (why do I need to?) 
    Marker.RegisterName("MarkerBlurEffect",MarkerBlurEffect); 

    // Instead of SetTarget, use SetTargetName on the registered name 
    Storyboard.SetTargetName(blurEffectAnimation, "MarkerBlurEffect"); 
    Storyboard.SetTargetProperty(blurEffectAnimation, 
    new PropertyPath(BlurEffect.RadiusProperty)); 

    Storyboard sb=new Storyboard(); 

    sb.Children.Add(blurEffectAnimation); 
    // Provide Marker to the Begin function in order to specify the name scope 
    // for the registered ("MarkerBlurEffect") name. Not doing this will result 
    // in an InvalidOperationException with the Message property set to: 
    // No applicable name scope exists to resolve the name 'MarkerBlurEffect'. 
    sb.Begin(Marker); 

Answer 1

是的......你說得對。由於Effect對象在樹中深處，您必須這樣做才能訪問它。或者你也可以從橢圓訪問您的效果，改變你的財產路徑是這樣的：

DoubleAnimation blurEffectAnimation = new DoubleAnimation 
{ 
    From = 0, 
    To = 10, 
    Duration = TimeSpan.FromSeconds(2.0) 
}; 

Storyboard.SetTarget(
    blurEffectAnimation, 
    Marker); 

Storyboard.SetTargetProperty(
    blurEffectAnimation, 
    new PropertyPath("(Effect).Radius")); 

Storyboard sb = new Storyboard(); 

sb.Children.Add(blurEffectAnimation); 
sb.Begin();