ActualWidth作为WPF动画中的值

Question

为什么我不能将ActualWidth作为一个值引用，我可以在代码中使用它。

XAML：

    <StackPanel>
        <Button x:Name="cmdVibrate" HorizontalAlignment="Center">
            <Button.Triggers>
                <EventTrigger RoutedEvent="Button.MouseEnter">
                    <BeginStoryboard>
                        <Storyboard >
                            <DoubleAnimation From="{Binding RelativeSource={RelativeSource Mode=Self},Path=ActualWidth}" By="200" AutoReverse="True" Duration="0:0:1" Storyboard.TargetProperty="Width"></DoubleAnimation>
                        </Storyboard>
                    </BeginStoryboard>
                </EventTrigger>
            </Button.Triggers>
            Mouse over me to shake
        </Button>
    </StackPanel>
</Window>

Answer 1

RelativeSource={RelativeSource Mode=Self}可能会引用DoubleAnimation (它没有ActualWidth属性)。相反，尝试查找祖先Button

From="{Binding RelativeSource={RelativeSource AncestorType={x:Type Button}},
               Path=ActualWidth}"

Xaml

<StackPanel>
    <Button x:Name="cmdVibrate" HorizontalAlignment="Center">
        <Button.Triggers>
            <EventTrigger RoutedEvent="Button.MouseEnter">
                <BeginStoryboard>
                    <Storyboard >
                        <DoubleAnimation From="{Binding RelativeSource={RelativeSource AncestorType={x:Type Button}}, Path=ActualWidth}"
                                         By="200"
                                         AutoReverse="True"
                                         Duration="0:0:1"
                                         Storyboard.TargetProperty="Width"></DoubleAnimation>
                    </Storyboard>
                </BeginStoryboard>
            </EventTrigger>
        </Button.Triggers>
        Mouse over me to shake
    </Button>
</StackPanel>