如何:使用关键帧针对对象进行动画处理
此示例演示如何使用关键帧对对象(本例中为 Page 控件的 Background 属性)进行动画处理。
示例
下面示例使用 ObjectAnimationUsingKeyFrames 类对 Page 控件的 Background 属性的颜色变化进行动画处理。 该示例动画将按固定时间间隔变为不同的背景画笔。 此动画使用 DiscreteObjectKeyFrame 类创建三个不同的关键帧。 动画按下列方式使用关键帧:
在第一秒结束时,对 LinearGradientBrush 类的实例进行动画处理。 示例的此部分将线性渐变应用于背景颜色,使颜色从黄色过渡到橙色再过渡到红色。
在下一秒结束时,对 RadialGradientBrush 类的实例进行动画处理。 示例的此部分将径向渐变应用于背景颜色,使颜色从白色过渡到蓝色再过渡到黑色。
在第三秒结束时,对 DrawingBrush 类的实例进行动画处理。 示例的此部分将棋盘图案应用于背景。
动画将再次开始并无限重复。
注意 |
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DiscreteObjectKeyFrame 是唯一可与 ObjectAnimationUsingKeyFrames 类一起使用的关键帧类型。像 DiscreteObjectKeyFrame 这样的关键帧会使值突然发生更改,也就是说,此示例中的颜色会突然发生变化。 |
<Page
xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://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,请参见 KeyFrame Animation Sample(KeyFrame 动画示例)。