WPF中的動畫寬度到實際寬度？

如何將元素的寬度從 0 設置為 WPF 中的實際寬度？

我試過這個：

<ControlTemplate.Triggers>
   <EventTrigger RoutedEvent="Loaded">
       <BeginStoryboard>
           <Storyboard>
               <DoubleAnimation Duration="0:0:0.3" To="{Binding ElementName=MyElement, Path=ActualWidth}" From="0" Storyboard.TargetProperty="Width" Storyboard.TargetName="MyElement" />
           </Storyboard>
       </BeginStoryboard>
   </EventTrigger>
</ControlTemplate.Triggers>

如果我將綁定更改為硬編碼值，例如100，則寬度會正確設置動畫，但我想綁定到元素的實際寬度。

如果重要的話，MyElement是一個邊框，我正在為一個標籤項設置動畫。

為了記錄，這也不起作用：

To="{Binding RelativeSource={RelativeSource AncestorType={x:Type Border}}, Path=ActualWidth}"

我確信這是錯誤的，原因有很多，請隨時告訴我我違反了多少 WPF 法律，但是.. 我通過創建自己的 BindableDoubleAnimation 解決了同樣的問題。

public class BindableDoubleAnimation : DoubleAnimationBase
{
   DoubleAnimation internalAnimation;

   public DoubleAnimation InternalAnimation { get { return internalAnimation; } }

   public double To
   {
       get { return (double)GetValue(ToProperty); }
       set { SetValue(ToProperty, value); }
   }

   /// <summary>
   /// Dependency backing property for the <see cref="To"/> property.
   /// </summary>
   public static readonly DependencyProperty ToProperty =
       DependencyProperty.Register("To", typeof(double), typeof(BindableDoubleAnimation), new UIPropertyMetadata(0d, new PropertyChangedCallback((s, e) =>
           {
               BindableDoubleAnimation sender = (BindableDoubleAnimation)s;
               sender.internalAnimation.To = (double)e.NewValue;
           })));


   public double From
   {
       get { return (double)GetValue(FromProperty); }
       set { SetValue(FromProperty, value); }
   }

   /// <summary>
   /// Dependency backing property for the <see cref="From"/> property.
   /// </summary>
   public static readonly DependencyProperty FromProperty =
       DependencyProperty.Register("From", typeof(double), typeof(BindableDoubleAnimation), new UIPropertyMetadata(0d, new PropertyChangedCallback((s, e) =>
       {
           BindableDoubleAnimation sender = (BindableDoubleAnimation)s;
           sender.internalAnimation.From = (double)e.NewValue;
       })));


   public BindableDoubleAnimation()
   {
       internalAnimation = new DoubleAnimation();
   }

   protected override double GetCurrentValueCore(double defaultOriginValue, double defaultDestinationValue, AnimationClock animationClock)
   {
       return internalAnimation.GetCurrentValue(defaultOriginValue, defaultDestinationValue, animationClock);
   }

   protected override Freezable CreateInstanceCore()
   {
       return internalAnimation.Clone();;
   }
}

我現在可以自由地為 To From 屬性使用綁定。

<local:BindableDoubleAnimation Storyboard.TargetProperty="Width" From="0" To="{Binding ActualWidth, RelativeSource={RelativeSource AncestorType=Window}}"/>

引用自：https://stackoverflow.com/questions/10994716