如何：使用关键帧对双精度属性值进行动画处理
更新：2007 年 11 月
此示例演示如何使用关键帧对采用 Double 的属性的值进行动画处理。
示例
下面的示例将一个矩形从屏幕一端移到另一端。此示例使用 DoubleAnimationUsingKeyFrames 类对应用于 Rectangle 的 TranslateTransform 的 X 属性进行动画处理。此动画（无限期地重复）按下列方式使用三个关键帧：
在最初三秒内，将使用 LinearDoubleKeyFrame 类的实例，使该矩形沿着某个路径以固定的速率从其起始位置移到 500 位置。线性关键帧（如 LinearDoubleKeyFrame）将在值之间创建平滑的线性过渡。
在第四秒结束时，将使用 DiscreteDoubleKeyFrame 类的实例，使矩形在一瞬间移到下一个位置。离散关键帧（如 DiscreteDoubleKeyFrame）将在值之间创建突然跳转。在本例中，矩形位于起始位置，然后突然出现在 500 位置。
在最后两秒钟内，使用 SplineDoubleKeyFrame 类的实例将矩形移回其起始位置。样条关键帧（如 SplineDoubleKeyFrame）将会根据 KeySpline 属性的值在各个值之间创建可变过渡。在本例中，矩形开始时缓慢移动，然后其速度以指数级加快，直到时间段结束。
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Shapes;
using System.Windows.Media.Animation;
using System.Windows.Media;
namespace Microsoft.Samples.KeyFrameExamples
{
/// <summary>
/// This example shows how to use the DoubleAnimationUsingKeyFrames class to
/// animate the position of an object.
/// Key frame animations enable you to create complex animations
/// by specifying multiple destination values
/// and controlling the animation's interpolation method.
/// </summary>
public class AltDoubleAnimationUsingKeyFramesExample : Page
{
public AltDoubleAnimationUsingKeyFramesExample()
{
Title = "DoubleAnimationUsingKeyFrames Example";
Background = Brushes.White;
Margin = new Thickness(20);
// Create a NameScope for this page so that
// Storyboards can be used.
NameScope.SetNameScope(this, new NameScope());
// Create a rectangle.
Rectangle aRectangle = new Rectangle();
aRectangle.Width = 100;
aRectangle.Height = 100;
aRectangle.Stroke = Brushes.Black;
aRectangle.StrokeThickness = 5;
// Create a Canvas to contain and
// position the rectangle.
Canvas containerCanvas = new Canvas();
containerCanvas.Width = 610;
containerCanvas.Height = 300;
containerCanvas.Children.Add(aRectangle);
Canvas.SetTop(aRectangle, 100);
Canvas.SetLeft(aRectangle, 10);
// Create a TranslateTransform to
// move the rectangle.
TranslateTransform animatedTranslateTransform =
new TranslateTransform();
aRectangle.RenderTransform = animatedTranslateTransform;
// Assign the TranslateTransform a name so that
// it can be targeted by a Storyboard.
this.RegisterName(
"AnimatedTranslateTransform", animatedTranslateTransform);
// Create a DoubleAnimationUsingKeyFrames to
// animate the TranslateTransform.
DoubleAnimationUsingKeyFrames translationAnimation
= new DoubleAnimationUsingKeyFrames();
translationAnimation.Duration = TimeSpan.FromSeconds(6);
// Animate from the starting position to 500
// over the first second using linear
// interpolation.
translationAnimation.KeyFrames.Add(
new LinearDoubleKeyFrame(
500, // Target value (KeyValue)
KeyTime.FromTimeSpan(TimeSpan.FromSeconds(3))) // KeyTime
);
// Animate from 500 (the value of the previous key frame)
// to 400 at 4 seconds using discrete interpolation.
// Because the interpolation is discrete, the rectangle will appear
// to "jump" from 500 to 400.
translationAnimation.KeyFrames.Add(
new DiscreteDoubleKeyFrame(
400, // Target value (KeyValue)
KeyTime.FromTimeSpan(TimeSpan.FromSeconds(4))) // KeyTime
);
// Animate from 400 (the value of the previous key frame) to 0
// over two seconds, starting at 4 seconds (the key time of the
// last key frame) and ending at 6 seconds.
translationAnimation.KeyFrames.Add(
new SplineDoubleKeyFrame(
0, // Target value (KeyValue)
KeyTime.FromTimeSpan(TimeSpan.FromSeconds(6)), // KeyTime
new KeySpline(0.6,0.0,0.9,0.0) // KeySpline
)
);
// Set the animation to repeat forever.
translationAnimation.RepeatBehavior = RepeatBehavior.Forever;
// Set the animation to target the X property
// of the object named "AnimatedTranslateTransform."
Storyboard.SetTargetName(translationAnimation, "AnimatedTranslateTransform");
Storyboard.SetTargetProperty(
translationAnimation, new PropertyPath(TranslateTransform.XProperty));
// Create a storyboard to apply the animation.
Storyboard translationStoryboard = new Storyboard();
translationStoryboard.Children.Add(translationAnimation);
// Start the storyboard after the rectangle loads.
aRectangle.Loaded += delegate(object sender, RoutedEventArgs e)
{
translationStoryboard.Begin(this);
};
Content = containerCanvas;
}
}
}
<!-- This example shows how to use the DoubleAnimationUsingKeyFrames to
animate the position of an object.
Key frame animations enable you to create complex animations
by specifying multiple destination values
and controlling the animation's interpolation method.
-->
<Page
xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml"
Title="DoubleAnimationUsingKeyFrames Example"
Background="White" Margin="20">
<Canvas Width="610" Height="300">
<!-- The position of this rectangle is animated using
a key frame animation. -->
<Rectangle
Canvas.Top="100"
Canvas.Left="10"
Height="100"
Width="100"
Stroke="Black"
StrokeThickness="5">
<Rectangle.RenderTransform>
<TranslateTransform x:Name="AnimatedTranslateTransform" />
</Rectangle.RenderTransform>
<Rectangle.Triggers>
<EventTrigger RoutedEvent="Rectangle.Loaded">
<BeginStoryboard>
<Storyboard>
<!-- Animate the TranslateTransform.X property using 3 KeyFrames
which animates the rectangle along a straight line.
This animation repeats indefinitely. -->
<DoubleAnimationUsingKeyFrames
Storyboard.TargetName="AnimatedTranslateTransform"
Storyboard.TargetProperty="X"
Duration="0:0:6"
RepeatBehavior="Forever">
<!-- Using a LinearDoubleKeyFrame, the rectangle moves
steadily from its starting position to 500 over
the first 3 seconds. -->
<LinearDoubleKeyFrame Value="500" KeyTime="0:0:3" />
<!-- Using a DiscreteDoubleKeyFrame, the rectangle suddenly
appears at 400 after the fourth second of the animation. -->
<DiscreteDoubleKeyFrame Value="400" KeyTime="0:0:4" />
<!-- Using a SplineDoubleKeyFrame, the rectangle moves
back to its starting point. The
animation starts out slowly at first and then speeds up.
This KeyFrame ends after the 6th
second. -->
<SplineDoubleKeyFrame KeySpline="0.6,0.0 0.9,0.00" Value="0" KeyTime="0:0:6" />
</DoubleAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Rectangle.Triggers>
</Rectangle>
</Canvas>
</Page>
有关完整示例，请参见 KeyFrame 动画示例。
为了与其他动画示例保持一致，此示例的代码版本使用 Storyboard 对象来应用 DoubleAnimationUsingKeyFrames。此外，在代码中应用单个动画时，更简便的做法是使用 BeginAnimation 方法而不是 Storyboard。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。