如何：沿着路径针对对象进行动画处理（偏移量进行累积的矩阵动画）
更新：2007 年 11 月
此示例演示如何使用 MatrixAnimationUsingPath 类沿着路径对对象进行动画处理，并在该动画重复时累积其偏移量值。
示例
下面的示例使用 MatrixAnimationUsingPath 对象对应用于某个按钮的 MatrixTransform 的 Matrix 属性进行动画处理。因此，按钮会沿着曲线路径移动。
另外，该示例将 IsOffsetCumulative 属性设置为 true，这会导致在该动画重复时累积动画矩阵的偏移量。由于偏移量会进行累积，因此，当该动画重复时，该按钮会移到屏幕上的更远处，而不是复位到起始位置。
<Page
xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml" Margin="20"
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">
<!-- The Button that is animated across the screen by animating
the MatrixTransform applied to the button. -->
<Button MinWidth="100" Content="A Button">
<Button.RenderTransform>
<MatrixTransform x:Name="myMatrixTransform">
<MatrixTransform.Matrix >
<Matrix />
</MatrixTransform.Matrix>
</MatrixTransform>
</Button.RenderTransform>
<Button.Triggers>
<EventTrigger RoutedEvent="Button.Click">
<BeginStoryboard>
<Storyboard>
<MatrixAnimationUsingPath
Storyboard.TargetName="myMatrixTransform"
Storyboard.TargetProperty="Matrix"
IsOffsetCumulative="True"
Duration="0:0:5"
RepeatBehavior="2x">
<MatrixAnimationUsingPath.PathGeometry>
<PathGeometry
Figures="M 10,100 C 35,0 135,0 160,100 180,190 285,200 310,100"
PresentationOptions:Freeze="True" />
</MatrixAnimationUsingPath.PathGeometry>
</MatrixAnimationUsingPath>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Button.Triggers>
</Button>
</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
{
/// <summary>
/// Shows how to use the MatrixAnimationUsingPath.IsOffsetCumulative
/// property to make a MatrixAnimatioinUsingPath accumulate
/// its values when it repeats.
/// </summary>
public class MatrixAnimationUsingPathExampleOffsetCumulative : Page
{
public MatrixAnimationUsingPathExampleOffsetCumulative()
{
this.Margin = new Thickness(20);
// Create a NameScope for the page so that
// we can use Storyboards.
NameScope.SetNameScope(this, new NameScope());
// Create a button.
Button aButton = new Button();
aButton.MinWidth = 100;
aButton.Content = "A Button";
// Create a MatrixTransform. This transform
// will be used to move the button.
MatrixTransform buttonMatrixTransform = new MatrixTransform();
aButton.RenderTransform = buttonMatrixTransform;
// Register the transform's name with the page
// so that it can be targeted by a Storyboard.
this.RegisterName("ButtonMatrixTransform", buttonMatrixTransform);
// Create a Canvas to contain the button
// and add it to the page.
// Although this example uses a Canvas,
// any type of panel will work.
Canvas mainPanel = new Canvas();
mainPanel.Width = 400;
mainPanel.Height = 400;
mainPanel.Children.Add(aButton);
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 MatrixAnimationUsingPath to move the
// button along the path by animating
// its MatrixTransform.
MatrixAnimationUsingPath matrixAnimation =
new MatrixAnimationUsingPath();
matrixAnimation.PathGeometry = animationPath;
// Set IsOffsetCumulative to true so that the animation
// values accumulate when its repeats.
matrixAnimation.IsOffsetCumulative = true;
matrixAnimation.Duration = TimeSpan.FromSeconds(5);
matrixAnimation.RepeatBehavior = new RepeatBehavior(2);
// Set the animation to target the Matrix property
// of the MatrixTransform named "ButtonMatrixTransform".
Storyboard.SetTargetName(matrixAnimation, "ButtonMatrixTransform");
Storyboard.SetTargetProperty(matrixAnimation,
new PropertyPath(MatrixTransform.MatrixProperty));
// Create a Storyboard to contain and apply the animation.
Storyboard pathAnimationStoryboard = new Storyboard();
pathAnimationStoryboard.Children.Add(matrixAnimation);
// Start the animation when the button is clicked.
aButton.Click += delegate(object sender, RoutedEventArgs e)
{
// Start the storyboard.
pathAnimationStoryboard.Begin(this);
};
}
}
}
请注意，尽管 IsOffsetCumulative 属性会使偏移量值在动画重复时累积，但它不会导致对旋转值进行累积。若要累积旋转值，请将该动画的 DoesRotateWithTangent 和 IsAngleCumulative 属性设置为 true。
有关完整示例，请参见 路径动画示例。有关演示如何沿着路径对 Matrix 值进行动画处理而不累积偏移量的示例，请参见如何：沿着路径针对对象进行动画处理（矩阵动画）。