此示例演示如何使用关键帧对对象进行动画处理，在本示例中，该对象是 Background 控件的属性 Page 。
示例：
以下示例使用ObjectAnimationUsingKeyFrames类对控件属性Page的颜色更改进行Background动画处理。 示例中的动画会定期更换背景画笔。 此动画使用 DiscreteObjectKeyFrame 类创建三个不同的关键帧。 动画采用以下方式使用关键帧：
在第一秒结束时，对类的 LinearGradientBrush 实例进行动画处理。 本部分将线性渐变应用于背景色，以便颜色从黄色过渡到橙色到红色。
下一秒结束时，将对 RadialGradientBrush 类的实例进行动画化。 本示例的本部分将径向渐变应用于背景色，以便颜色从白色过渡到蓝色到黑色。
在第三秒结束时，将 DrawingBrush 类的实例进行动画处理。 本示例的此部分将棋盘模式应用于背景。
动画会再次开始，并无限期重复。
注释
DiscreteObjectKeyFrame 是可用于 ObjectAnimationUsingKeyFrames 类的唯一关键帧类型。 关键帧，如 DiscreteObjectKeyFrame 在值中创建突然变化，即此示例中的颜色更改突然发生。
<Page
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
<Page.Triggers>
<EventTrigger RoutedEvent="Page.Loaded">
<BeginStoryboard>
<Storyboard>
<!-- ObjectAnimationUsingKeyFrames is used to animate properties that take
an object as a value. This animation lasts for 4 seconds using 3 KeyFrames which
swap different brush objects at regular intervals, making the background of the Page
change. -->
<ObjectAnimationUsingKeyFrames
Storyboard.TargetProperty="Background"
Duration="0:0:4" RepeatBehavior="Forever">
<ObjectAnimationUsingKeyFrames.KeyFrames>
<!-- Note: Only discrete interpolation (DiscreteObjectKeyFrame) is available for
use with ObjectAnimationUsingKeyFrames which merely swaps objects according to
a specified timeline. Other types of interpolation are too problematic to apply
to objects. -->
<!-- Using a DiscreteObjectKeyFrame, the Page Background suddenly changes
to a LinearGradientBrush after the first second of the animation. -->
<DiscreteObjectKeyFrame KeyTime="0:0:1">
<DiscreteObjectKeyFrame.Value>
<LinearGradientBrush>
<LinearGradientBrush.GradientStops>
<GradientStop Color="Yellow" Offset="0.0" />
<GradientStop Color="Orange" Offset="0.5" />
<GradientStop Color="Red" Offset="1.0" />
</LinearGradientBrush.GradientStops>
</LinearGradientBrush>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
<!-- Using a DiscreteObjectKeyFrame, the Page Background suddenly changes
to a RadialGradientBrush after the second second of the animation. -->
<DiscreteObjectKeyFrame KeyTime="0:0:2">
<DiscreteObjectKeyFrame.Value>
<RadialGradientBrush GradientOrigin="0.75,0.25">
<RadialGradientBrush.GradientStops>
<GradientStop Color="White" Offset="0.0" />
<GradientStop Color="MediumBlue" Offset="0.5" />
<GradientStop Color="Black" Offset="1.0" />
</RadialGradientBrush.GradientStops>
</RadialGradientBrush>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
<!-- Using a DiscreteObjectKeyFrame, the Page Background suddenly
changes to a DrawingBrush (creates a checkerboard pattern) after the
third second of the animation. -->
<DiscreteObjectKeyFrame KeyTime="0:0:3">
<DiscreteObjectKeyFrame.Value>
<DrawingBrush Viewport="0,0,0.25,0.25" TileMode="Tile">
<DrawingBrush.Drawing>
<DrawingGroup>
<DrawingGroup.Children>
<GeometryDrawing Brush="White">
<GeometryDrawing.Geometry>
<RectangleGeometry Rect="0,0,1,1" />
</GeometryDrawing.Geometry>
</GeometryDrawing>
<GeometryDrawing Brush="Black"
Geometry="M 0,0 L0,0.5 0.5,0.5 0.5,1 1,1 1,0.5 0.5,0.5 0.5,0" />
</DrawingGroup.Children>
</DrawingGroup>
</DrawingBrush.Drawing>
</DrawingBrush>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames.KeyFrames>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Page.Triggers>
</Page>
有关完整示例，请参阅 关键帧动画示例。
