如何：將動畫輸出值加入至動畫啟動值
此範例示範如何將動畫輸出值新增至動畫起始值。
範例
IsAdditive 屬性會指定是否要將動畫的輸出值新增至動畫屬性的起始值 (基礎值)。 您可以使用 IsAdditive 屬性搭配最基本的動畫和最主要畫面格動畫。 如需詳細資訊，請參閱動畫概觀和主要畫面格動畫概觀。
下列範例示範使用 DoubleAnimation.IsAdditive 屬性搭配 DoubleAnimation，以及使用 DoubleAnimationUsingKeyFrames.IsAdditive 屬性搭配 DoubleAnimationUsingKeyFrames 的效果。
<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<StackPanel Margin="20" >
<!-- This rectangle is animated with DoubleAnimation and IsAdditive set to "True". -->
<Rectangle Name="withIsAdditive"
Width="100" Height="20" Margin="12,0,0,5" Fill="#AA3333FF" HorizontalAlignment="Left" />
<!-- This rectangle is animated with DoubleAnimation and IsAdditive set to "False". -->
<Rectangle Name="withoutIsAdditive"
Width="100" Height="20" Margin="12,0,0,5" Fill="#AA3333FF" HorizontalAlignment="Left" />
<!-- This rectangle is animated with DoubleAnimationUsingKeyFrames and IsAdditive set to "True". -->
<Rectangle Name="withIsAdditiveUsingKeyFrames"
Width="100" Height="20" Margin="12,0,0,5" Fill="#AA3333FF" HorizontalAlignment="Left" />
<!-- This rectangle is animated with DoubleAnimationUsingKeyFrames and IsAdditive set to "False". -->
<Rectangle Name="withoutIsAdditiveUsingKeyFrames"
Width="100" Height="20" Margin="12,0,0,5" Fill="#AA3333FF" HorizontalAlignment="Left" />
<!-- Create a button to restart the animations. -->
<Button Margin="0,30,0,0" HorizontalAlignment="Left">
Restart Animations
<Button.Triggers>
<EventTrigger RoutedEvent="Button.Click">
<BeginStoryboard>
<Storyboard>
<!-- DoubleAnimation with IsAdditive set to "True". Because IsAdditive is set to "True" the
actual starting value of the animation is equal to the sum of the default starting
value of 100 (From="100)and the animation output value of 100 (From="100" To="200") Therefore
the animation begins at 200 pixels. Notice that each time the button is clicked and the
animation is initiated, the animation starting value builds upon the preceeding ending value. -->
<DoubleAnimation
Storyboard.TargetName="withIsAdditive"
Storyboard.TargetProperty="Width"
Duration="0:0:3" From="100" To="200" IsAdditive="True" />
<!-- DoubleAnimation with IsAdditive set to "False". The starting value is the default starting
value of 100 pixels and subsequent animations do not build on earlier ones. -->
<DoubleAnimation
Storyboard.TargetName="withoutIsAdditive"
Storyboard.TargetProperty="Width"
Duration="0:0:3" From="100" To="200" IsAdditive="False" />
<!-- DoubleAnimationUsingKeyFrames with IsAdditive set to "True". Similar to the DoubleAnimation
above, this animation adds its output value to its starting value. Note that the output value
is the total output value from all the key frames for a total output of 100 pixels. -->
<DoubleAnimationUsingKeyFrames
Storyboard.TargetName="withIsAdditiveUsingKeyFrames"
Storyboard.TargetProperty="Width"
IsAdditive="True" >
<DoubleAnimationUsingKeyFrames.KeyFrames>
<LinearDoubleKeyFrame Value="100" KeyTime="0:0:0" />
<LinearDoubleKeyFrame Value="130" KeyTime="0:0:1" />
<SplineDoubleKeyFrame KeySpline="0.6,0.0 0.9,0.00" Value="200" KeyTime="0:0:3" />
</DoubleAnimationUsingKeyFrames.KeyFrames>
</DoubleAnimationUsingKeyFrames>
<!-- DoubleAnimationUsingKeyFrames with IsAdditive set to "False". The starting value is the
default starting value of 100 pixels and subsequent animations do not build on earlier ones. -->
<DoubleAnimationUsingKeyFrames
Storyboard.TargetName="withoutIsAdditiveUsingKeyFrames"
Storyboard.TargetProperty="Width"
IsAdditive="False" >
<DoubleAnimationUsingKeyFrames.KeyFrames>
<LinearDoubleKeyFrame Value="100" KeyTime="0:0:0" />
<LinearDoubleKeyFrame Value="130" KeyTime="0:0:1" />
<SplineDoubleKeyFrame KeySpline="0.6,0.0 0.9,0.00" Value="200" KeyTime="0:0:3" />
</DoubleAnimationUsingKeyFrames.KeyFrames>
</DoubleAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Button.Triggers>
</Button>
</StackPanel>
</Page>
