如何：沿着路径针对对象进行动画处理（点动画）
更新：2007 年 11 月
下面的示例演示如何使用 PointAnimationUsingPath 对象来沿着曲线路径针对 Point 进行动画处理。
示例
下面的示例沿着由 PathGeometry 定义的路径来移动 EllipseGeometry。椭圆几何形状的位置由值为 Point 的 Center 属性来指定；若要移动椭圆几何形状，请对它的 Center 属性进行动画处理。此示例使用 PointAnimationUsingPath 来针对 EllipseGeometry 对象的 Center 属性进行动画处理。
<Page
xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml"
xmlns:PresentationOptions="https://schemas.microsoft.com/winfx/2006/xaml/presentation/options"
xmlns:mc="https://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="PresentationOptions">
<Canvas Width="400" Height="400">
<Path Fill="Blue" Margin="15,15,15,15">
<Path.Data>
<!-- The EllipseGemetry specifies the shape and position of the Ellipse. The
Center property is animated, causing the Ellipse to animate across the screen-->
<EllipseGeometry x:Name="MyAnimatedEllipseGeometry"
Center="10,100" RadiusX="15" RadiusY="15" />
</Path.Data>
<Path.Triggers>
<EventTrigger RoutedEvent="Path.Loaded">
<BeginStoryboard Name="MyBeginStoryboard">
<Storyboard>
<!-- Animates the ellipse along the path. -->
<PointAnimationUsingPath
Storyboard.TargetName="MyAnimatedEllipseGeometry"
Storyboard.TargetProperty="Center"
Duration="0:0:5"
RepeatBehavior="Forever" >
<PointAnimationUsingPath.PathGeometry>
<PathGeometry
Figures="M 10,100 C 35,0 135,0 160,100 180,190 285,200 310,100"
PresentationOptions:Freeze="True" />
</PointAnimationUsingPath.PathGeometry>
</PointAnimationUsingPath>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Path.Triggers>
</Path>
</Canvas>
</Page>
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Navigation;
using System.Windows.Shapes;
namespace SDKSample
{
public class PointAnimationUsingPathExample : Page
{
public PointAnimationUsingPathExample()
{
// Create a NameScope for the page so that
// we can use Storyboards.
NameScope.SetNameScope(this, new NameScope());
// Create the EllipseGeometry to animate.
EllipseGeometry animatedEllipseGeometry =
new EllipseGeometry(new Point(10, 100), 15, 15);
// Register the EllipseGeometry's name with
// the page so that it can be targeted by a
// storyboard.
this.RegisterName("AnimatedEllipseGeometry", animatedEllipseGeometry);
// Create a Path element to display the geometry.
Path ellipsePath = new Path();
ellipsePath.Data = animatedEllipseGeometry;
ellipsePath.Fill = Brushes.Blue;
ellipsePath.Margin = new Thickness(15);
// Create a Canvas to contain ellipsePath
// and add it to the page.
Canvas mainPanel = new Canvas();
mainPanel.Width = 400;
mainPanel.Height = 400;
mainPanel.Children.Add(ellipsePath);
this.Content = mainPanel;
// Create the animation path.
PathGeometry animationPath = new PathGeometry();
PathFigure pFigure = new PathFigure();
pFigure.StartPoint = new Point(10, 100);
PolyBezierSegment pBezierSegment = new PolyBezierSegment();
pBezierSegment.Points.Add(new Point(35, 0));
pBezierSegment.Points.Add(new Point(135, 0));
pBezierSegment.Points.Add(new Point(160, 100));
pBezierSegment.Points.Add(new Point(180, 190));
pBezierSegment.Points.Add(new Point(285, 200));
pBezierSegment.Points.Add(new Point(310, 100));
pFigure.Segments.Add(pBezierSegment);
animationPath.Figures.Add(pFigure);
// Freeze the PathGeometry for performance benefits.
animationPath.Freeze();
// Create a PointAnimationgUsingPath to move
// the EllipseGeometry along the animation path.
PointAnimationUsingPath centerPointAnimation =
new PointAnimationUsingPath();
centerPointAnimation.PathGeometry = animationPath;
centerPointAnimation.Duration = TimeSpan.FromSeconds(5);
centerPointAnimation.RepeatBehavior = RepeatBehavior.Forever;
// Set the animation to target the Center property
// of the EllipseGeometry named "AnimatedEllipseGeometry".
Storyboard.SetTargetName(centerPointAnimation, "AnimatedEllipseGeometry");
Storyboard.SetTargetProperty(centerPointAnimation,
new PropertyPath(EllipseGeometry.CenterProperty));
// Create a Storyboard to contain and apply the animation.
Storyboard pathAnimationStoryboard = new Storyboard();
pathAnimationStoryboard.RepeatBehavior = RepeatBehavior.Forever;
pathAnimationStoryboard.AutoReverse = true;
pathAnimationStoryboard.Children.Add(centerPointAnimation);
// Start the Storyboard when ellipsePath is loaded.
ellipsePath.Loaded += delegate(object sender, RoutedEventArgs e)
{
// Start the storyboard.
pathAnimationStoryboard.Begin(this);
};
}
}
}
有关完整示例，请参见 路径动画示例。
上一个示例的代码版本使用 Storyboard 来对 EllipseGeometry 进行动画处理，即使仅应用了一个动画也是如此。通常，Storyboard 是应用多个动画的最简便方法，因为这些动画可以由同一个 Storyboard 来控制。但是，在使用代码时，向属性应用单个动画的最简便方法就是使用 BeginAnimation 方法。有关示例，请参见如何：在不使用演示图板的情况下对属性进行动画处理。