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我正在尝试使用 ObjectAnimationUsingKeyFrames 为“样式”属性设置动画。当我运行下面的示例时，我只看到空窗口并且没有任何异常。

几乎相同的示例在 Silverlight 中工作。如果我直接分配控件的“样式”属性，它也可以在 WPF 中工作。有谁知道是否可以在 WPF 中为“样式”属性设置动画？

非常感谢。

<Window x:Class="WpfApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:this="clr-namespace:WpfApplication1"
    Title="MainWindow" Height="350" Width="525"
    >
<Window.Resources>
    <ResourceDictionary>

        <Style x:Key="TestStyle" TargetType="Control">
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate>
                        <Canvas x:Name="Rectangle">
                            <Rectangle Width="200" Height="150" Fill="Red"/>
                        </Canvas>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </ResourceDictionary>
</Window.Resources>
<Canvas>
    <Canvas.Triggers>
        <EventTrigger RoutedEvent="Canvas.Loaded">
            <BeginStoryboard>
                <Storyboard>
                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Target" Storyboard.TargetProperty="Style" >
                        <DiscreteObjectKeyFrame KeyTime="0:0:0.0" Value="{StaticResource ResourceKey=TestStyle}" />
                    </ObjectAnimationUsingKeyFrames>
                </Storyboard>
            </BeginStoryboard>
        </EventTrigger>
    </Canvas.Triggers>

    <Canvas.Children>
        <ContentControl x:Name="Target"/>
    </Canvas.Children>
</Canvas>

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1 回答 1

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When ObjectAnimationUsingKeyFrames tries to animate to a value that is derived from DependencyObject, it attempts to freeze the object first. If the object can't be frozen, it throws an exception and the animation does not run.

If you are animating a value of a custom type that you wrote, it appears you need to either derive from Freezable or NOT derive from DependencyObject.

For properties that already exist that derive from DependencyObject and not Freezable, you can't animate them (StyleProperty or TemplateProperty are cases in point). Try using a property setter inside of a style:

<Style.Triggers>
  <Trigger Property="IsEnabled" Value="True">
    <Setter Property="Template" Value="{StaticResource TestTemplate}"/>
  </Trigger>
</Style.Triggers>

Build all of the transition logic into the style instead of switching between different styles. A challenge that you may have with this is that the target property has to be a dependency property so you can't use IsLoaded.

I hope you find this useful.

One final thought: It is possible to define custom animations, although I have not done this myself. There's an outside chance that you could write your own custom "ObjectAnimation" that would not be restricted to Freezable or non-DependencyObject classes.

于 2011-03-23T13:55:50.343 回答