如何：使用关键帧对边框的粗细进行动画处理
此示例演示如何对 Border 的 BorderThickness 属性进行动画处理。
示例
下面的示例使用 ThicknessAnimationUsingKeyFrames 类对 Border 的 BorderThickness 属性进行动画处理。 此动画按下列方式使用三个关键帧：
在最初的半秒内，将使用 LinearThicknessKeyFrame 类的实例逐渐增加边框的粗细。 此示例使用 LinearThicknessKeyFrame 在值之间创建平滑的线性递增。
在接下来的半秒结束时，将使用 DiscreteThicknessKeyFrame 类的实例突然增加边框的粗细。 离散关键帧（如从 DiscreteThicknessKeyFrame 派生的那些关键帧）将在值之间创建突然跳转，使动画出现跳帧效果。
在最后两秒内，将使用 SplineThicknessKeyFrame 类的实例减小边框的粗细。 样条关键帧与从 SplineThicknessKeyFrame 派生的关键帧一样，根据 KeySpline 属性的值在各个值之间创建可变过渡。 在此关键帧中，动画一开始较慢，然后以指数级加速，直至时间段结束。
<!-- This example shows how to use the ThicknessAnimationUsingKeyFrames to create
an animation on the BorderThickness property of a Border. -->
<Page xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml"
x:Class="Microsoft.Samples.KeyFrameExamples.ThicknessAnimationUsingKeyFramesExample"
Name="myRootElement"
WindowTitle="ThicknessAnimationUsingKeyFrames Example">
<StackPanel Orientation="Vertical" HorizontalAlignment="Center">
<Border Background="#99FFFFFF" BorderBrush="#CCCCFF" BorderThickness="1"
Margin="0,60,0,20" Padding="20" >
<Border.Triggers>
<EventTrigger RoutedEvent="Border.Loaded">
<BeginStoryboard>
<Storyboard>
<!-- Animating the BorderThickness property uses 3 KeyFrames. -->
<ThicknessAnimationUsingKeyFrames
Storyboard.TargetProperty="BorderThickness"
Duration="0:0:5" FillBehavior="HoldEnd" RepeatBehavior="Forever">
<ThicknessAnimationUsingKeyFrames.KeyFrames>
<!-- Using a LinearThicknessKeyFrame, thickness increases gradually
over the first half second of the animation. -->
<LinearThicknessKeyFrame KeyTime="0:0:0.5">
<LinearThicknessKeyFrame.Value>
<Thickness Left="8" Right="8" Top="6" Bottom="6" />
</LinearThicknessKeyFrame.Value>
</LinearThicknessKeyFrame>
<!-- Using a DiscreteThicknessKeyFrame, thickness increases suddenly
after the first second of the animation. -->
<DiscreteThicknessKeyFrame KeyTime="0:0:1">
<DiscreteThicknessKeyFrame.Value>
<Thickness Left="28" Right="28" Top="24" Bottom="24" />
</DiscreteThicknessKeyFrame.Value>
</DiscreteThicknessKeyFrame>
<!-- Using a SplineThicknessKeyFrame, thickness decreases slowly at first
and then suddenly contracts. This KeyFrame takes 2 seconds. -->
<SplineThicknessKeyFrame KeySpline="0.6,0.0 0.9,0.00" KeyTime="0:0:3">
<SplineThicknessKeyFrame.Value>
<Thickness Left="1" Right="1" Top="1" Bottom="8" />
</SplineThicknessKeyFrame.Value>
</SplineThicknessKeyFrame>
</ThicknessAnimationUsingKeyFrames.KeyFrames>
</ThicknessAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Border.Triggers>
<TextBlock>
This example shows how to use the ThicknessAnimationUsingKeyFrames to create
an animation on the BorderThickness property of a Border.
</TextBlock>
</Border>
</StackPanel>
</Page>
有关完整示例，请参见 KeyFrame Animation Sample（KeyFrame 动画示例）。