混合交互行为给出了“指向不可变实例的点”。错误

Question

我有一个 UserControl，它是其他用户控件的基类，显示在“模态视图”中。
我希望所有用户控件在显示时淡入，在关闭时淡出。我还希望用户能够移动控件。我的构造函数如下所示：

var tg = new TransformGroup();
tg.Children.Add(new ScaleTransform());
RenderTransform = tg;
var behaviors = Interaction.GetBehaviors(this);
behaviors.Add(new TranslateZoomRotateBehavior());  

Loaded += ModalDialogBase_Loaded;

ModalDialogBase_Loaded 方法如下

private void ModalDialogBase_Loaded(object sender, RoutedEventArgs e)
{
    var fadeInStoryboard = (Storyboard)TryFindResource("modalDialogFadeIn");
    fadeInStoryboard.Begin(this);
}

所示： 当我按下控件上的关闭按钮时，将调用此方法：

protected virtual void Close()
{
    var fadeOutStoryboard = (Storyboard)TryFindResource("modalDialogFadeOut");  
    fadeOutStoryboard = fadeOutStoryboard.Clone();
    fadeOutStoryboard.Completed += delegate
    {
        RaiseEvent(new RoutedEventArgs(ClosedEvent));
    };
    fadeOutStoryboard.Begin(this);
}

淡出的情节提要如下所示：

<Storyboard x:Key="modalDialogFadeOut">
    <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[0].(ScaleTransform.ScaleX)" Storyboard.TargetName="{x:Null}">
        <EasingDoubleKeyFrame KeyTime="0" Value="1">
            <EasingDoubleKeyFrame.EasingFunction>
                <BackEase EasingMode="EaseIn" Amplitude="0.3" />
            </EasingDoubleKeyFrame.EasingFunction>
        </EasingDoubleKeyFrame>
        <EasingDoubleKeyFrame KeyTime="0:0:0.4" Value="0">
            <EasingDoubleKeyFrame.EasingFunction>
                <BackEase EasingMode="EaseIn" Amplitude="0.3" />
            </EasingDoubleKeyFrame.EasingFunction>
        </EasingDoubleKeyFrame>
    </DoubleAnimationUsingKeyFrames>
    <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[0].(ScaleTransform.ScaleY)" Storyboard.TargetName="{x:Null}">
        <EasingDoubleKeyFrame KeyTime="0" Value="1">
            <EasingDoubleKeyFrame.EasingFunction>
                <BackEase EasingMode="EaseIn" Amplitude="0.3" />
            </EasingDoubleKeyFrame.EasingFunction>
        </EasingDoubleKeyFrame>
        <EasingDoubleKeyFrame KeyTime="0:0:0.4" Value="0">
            <EasingDoubleKeyFrame.EasingFunction>
                <BackEase EasingMode="EaseIn" Amplitude="0.3" />
            </EasingDoubleKeyFrame.EasingFunction>
        </EasingDoubleKeyFrame>
    </DoubleAnimationUsingKeyFrames>
    <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="{x:Null}">
        <EasingDoubleKeyFrame KeyTime="0" Value="1" />
        <EasingDoubleKeyFrame KeyTime="0:0:0.3" Value="0" />
        <EasingDoubleKeyFrame KeyTime="0:0:0.4" Value="0" />
    </DoubleAnimationUsingKeyFrames>
</Storyboard>

如果显示用户控件，而用户不显示在屏幕上移动它，一切正常。但是，如果用户确实移动控件，则在启动 modalDialogFadeOut 故事板时会出现以下错误：

路径“(0).(1)[0].(2)”中的“Children”属性值指向不可变“System.Windows.Media.TransformCollection”的实例。

我该如何解决这个问题？

Answer 1

问题在于 TranslateZoomRotateBehavior 将 ScaleTransform 替换为 MatrixTransform，导致 Storyboard 中的前两个动画指向不再存在的属性。

由于您无法对矩阵的值进行动画处理以获得淡出效果，因此我将使用额外的容器控件。最外面的行为，然后是内部的行为在视觉上淡出。