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我正在为 WPF 应用程序开发倒计时控件。以下 xaml 演示了我所追求的：

<Canvas>
    <Canvas>
        <Ellipse Width="110" Height="110" Fill="Black" Canvas.Left="95" Canvas.Top="95" />
        <Ellipse Width="100" Height="100" Fill="Red" Canvas.Left="100" Canvas.Top="100" />
        <TextBlock VerticalAlignment="Center" HorizontalAlignment="Center" FontSize="72" Canvas.Left="131" Canvas.Top="100">3</TextBlock>
    </Canvas>
    <Canvas>
        <Path Stroke="Blue" Fill="White">
            <Path.Data>
                <PathGeometry>
                    <PathFigure StartPoint="150,150">
                        <LineSegment Point="200,150" />
                        <ArcSegment x:Name="arc1" Point="200,150" Size="50,50" SweepDirection="Clockwise" />
                        <ArcSegment x:Name="arc2" Point="200,150" Size="50,50" SweepDirection="Clockwise" />
                        <LineSegment Point="150,150" />
                    </PathFigure>
                </PathGeometry>
            </Path.Data>
            <Path.Triggers>
                <EventTrigger RoutedEvent="Path.Loaded">
                    <BeginStoryboard>
                        <Storyboard Duration="0:0:1" Storyboard.TargetProperty="Point" RepeatBehavior="Forever">
                            <PointAnimationUsingPath Duration="0:0:0.5" Storyboard.TargetName="arc1">
                                <PointAnimationUsingPath.PathGeometry>
                                    <PathGeometry>
                                        <PathFigure StartPoint="200,150">
                                            <ArcSegment Size="50,50" Point="100,150" SweepDirection="Clockwise" />
                                        </PathFigure>
                                    </PathGeometry>
                                </PointAnimationUsingPath.PathGeometry>
                            </PointAnimationUsingPath>
                            <PointAnimationUsingPath Duration="0:0:0.5" Storyboard.TargetName="arc2">
                                <PointAnimationUsingPath.PathGeometry>
                                    <PathGeometry>
                                        <PathFigure StartPoint="200,150">
                                            <ArcSegment Size="50,50" Point="100,150" SweepDirection="Clockwise" />
                                        </PathFigure>
                                    </PathGeometry>
                                </PointAnimationUsingPath.PathGeometry>
                            </PointAnimationUsingPath>
                            <PointAnimationUsingPath BeginTime="0:0:0.5" Duration="0:0:0.5" Storyboard.TargetName="arc2">
                                <PointAnimationUsingPath.PathGeometry>
                                    <PathGeometry>
                                        <PathFigure StartPoint="100,150">
                                            <ArcSegment Size="50,50" Point="200,150" SweepDirection="Clockwise" />
                                        </PathFigure>
                                    </PathGeometry>
                                </PointAnimationUsingPath.PathGeometry>
                            </PointAnimationUsingPath>
                        </Storyboard>
                    </BeginStoryboard>
                </EventTrigger>
            </Path.Triggers>
        </Path>          
    </Canvas>
</Canvas>

现在，我不想让整个事情变白，而是想“揭示”倒计时中的下一个数字。我认为使用 OpacityMask 会起作用，但是当我尝试时，事情变得很奇怪。这是我正在处理的 xaml：

<Canvas>
    <Canvas>
        <Ellipse Width="110" Height="110" Fill="Black" Canvas.Left="95" Canvas.Top="95" />
        <Ellipse Width="100" Height="100" Fill="Red" Canvas.Left="100" Canvas.Top="100" />
        <TextBlock VerticalAlignment="Center" HorizontalAlignment="Center" FontSize="72" Canvas.Left="131" Canvas.Top="100">3</TextBlock>
    </Canvas>
    <Canvas>
        <Ellipse Width="110" Height="110" Fill="Black" Canvas.Left="95" Canvas.Top="95" />
        <Ellipse Width="100" Height="100" Fill="Yellow" Canvas.Left="100" Canvas.Top="100" />
        <TextBlock VerticalAlignment="Center" HorizontalAlignment="Center" FontSize="72" Canvas.Left="131" Canvas.Top="100">2</TextBlock>
        <Canvas.OpacityMask>
            <VisualBrush>
                <VisualBrush.Visual>
                    <Path Stroke="Blue" Fill="White">
                        <Path.Data>
                            <PathGeometry>
                                <PathFigure StartPoint="150,150">
                                    <LineSegment Point="200,150" />
                                    <ArcSegment x:Name="arc1" Point="200,150" Size="50,50" SweepDirection="Clockwise" />
                                    <ArcSegment x:Name="arc2" Point="200,150" Size="50,50" SweepDirection="Clockwise" />
                                    <LineSegment Point="150,150" />
                                </PathFigure>
                            </PathGeometry>
                        </Path.Data>
                        <Path.Triggers>
                            <EventTrigger RoutedEvent="Path.Loaded">
                                <BeginStoryboard>
                                    <Storyboard Duration="0:0:10" Storyboard.TargetProperty="Point" RepeatBehavior="Forever">
                                        <PointAnimationUsingPath Duration="0:0:5" Storyboard.TargetName="arc1">
                                            <PointAnimationUsingPath.PathGeometry>
                                                <PathGeometry>
                                                    <PathFigure StartPoint="200,150">
                                                        <ArcSegment Size="50,50" Point="100,150" SweepDirection="Clockwise" />
                                                    </PathFigure>
                                                </PathGeometry>
                                            </PointAnimationUsingPath.PathGeometry>
                                        </PointAnimationUsingPath>
                                        <PointAnimationUsingPath Duration="0:0:5" Storyboard.TargetName="arc2">
                                            <PointAnimationUsingPath.PathGeometry>
                                                <PathGeometry>
                                                    <PathFigure StartPoint="200,150">
                                                        <ArcSegment Size="50,50" Point="100,150" SweepDirection="Clockwise" />
                                                    </PathFigure>
                                                </PathGeometry>
                                            </PointAnimationUsingPath.PathGeometry>
                                        </PointAnimationUsingPath>
                                        <PointAnimationUsingPath BeginTime="0:0:5" Duration="0:0:5" Storyboard.TargetName="arc2">
                                            <PointAnimationUsingPath.PathGeometry>
                                                <PathGeometry>
                                                    <PathFigure StartPoint="100,150">
                                                        <ArcSegment Size="50,50" Point="200,150" SweepDirection="Clockwise" />
                                                    </PathFigure>
                                                </PathGeometry>
                                            </PointAnimationUsingPath.PathGeometry>
                                        </PointAnimationUsingPath>
                                    </Storyboard>
                                </BeginStoryboard>
                            </EventTrigger>
                        </Path.Triggers>
                    </Path>
                </VisualBrush.Visual>
            </VisualBrush>
        </Canvas.OpacityMask>                      
    </Canvas>
</Canvas>

我不确定如何描述正在发生的事情，或者它为什么会这样，但这不是我想要的，也不是我所期望的。我缺少一些简单的东西吗？或者任何人都可以提供一种替代方法来完成我想要的吗？

4

1 回答 1

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我发现了这个问题。它与我用来创建不透明蒙版的视觉画笔的视口/视框有关。这是相关的变化：

<Canvas.OpacityMask>
            <VisualBrush Viewbox="0,0,300,300" ViewboxUnits="Absolute" Viewport="0,0,300,300" ViewportUnits="Absolute"> ...

无论如何，我都不是 WPF 专家，但我对出了什么问题的理解如下。画笔的默认视口从边界容器的左上角开始。在我的情况下，边界容器是我制作动画的路径。在动画期间，容器的左上角发生了变化。组成路径的不同部分是相对于这个不断变化的左上点定义的。基本上，它们是相对于移动目标绘制的。视图框设置表明我们希望使用其使用的相同坐标系来处理整个原始视觉。

任何对正在发生的事情有更好理解的人都可以给出更清晰的解释，随时编辑此答案或添加评论。

于 2012-06-13T11:49:34.000 回答