如何：在使用演示图板对属性进行动画处理后设置该属性
在某些情况下，在对属性进行动画处理之后，似乎无法更改该属性的值。
示例
在下面的示例中，Storyboard 用于对 SolidColorBrush 的颜色进行动画处理。 当单击按钮时将触发演示图板。 处理 Completed 事件以便在 ColorAnimation 完成时通知程序。
<Button
Content="Animate and Then Set Example 1">
<Button.Background>
<SolidColorBrush x:Name="Button1BackgroundBrush"
Color="Red" />
</Button.Background>
<Button.Triggers>
<EventTrigger RoutedEvent="Button.Click">
<BeginStoryboard>
<Storyboard>
<ColorAnimation
Storyboard.TargetName="Button1BackgroundBrush"
Storyboard.TargetProperty="Color"
From="Red" To="Yellow" Duration="0:0:5"
FillBehavior="HoldEnd"
Completed="setButton1BackgroundBrushColor" />
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Button.Triggers>
</Button>
在 ColorAnimation 完成之后，程序尝试将画笔的颜色改为蓝色。
Private Sub setButton1BackgroundBrushColor(ByVal sender As Object, ByVal e As EventArgs)
' Does not appear to have any effect:
' the brush remains yellow.
Button1BackgroundBrush.Color = Colors.Blue
End Sub
private void setButton1BackgroundBrushColor(object sender, EventArgs e)
{
// Does not appear to have any effect:
// the brush remains yellow.
Button1BackgroundBrush.Color = Colors.Blue;
}
上面的代码似乎未起任何作用：画笔仍然保持为黄色，即对画笔进行动画处理的 ColorAnimation 所提供的值。 基础属性值（基值）实际上已改为蓝色。 但是，因为 ColorAnimation 仍然在重写基值，所以有效值（或者说当前值）仍保持为黄色。 如果需要将基值再次变为有效值，则必须禁止动画影响该属性。 使用演示图板动画，可以有三种方法实现此目标：
将动画的 FillBehavior 属性设置为 Stop
移除整个演示图板。
从单个属性移除动画。
将动画的 FillBehavior 属性设置为 Stop
通过将 FillBehavior 设置为 Stop，即通知动画在到达其活动期末尾后停止影响其目标属性。
<Button
Content="Animate and Then Set Example 2">
<Button.Background>
<SolidColorBrush x:Name="Button2BackgroundBrush"
Color="Red" />
</Button.Background>
<Button.Triggers>
<EventTrigger RoutedEvent="Button.Click">
<BeginStoryboard>
<Storyboard>
<ColorAnimation
Storyboard.TargetName="Button2BackgroundBrush"
Storyboard.TargetProperty="Color"
From="Red" To="Yellow" Duration="0:0:5"
FillBehavior="Stop"
Completed="setButton2BackgroundBrushColor" />
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Button.Triggers>
</Button>
Private Sub setButton2BackgroundBrushColor(ByVal sender As Object, ByVal e As EventArgs)
' This appears to work:
' the brush changes to blue.
Button2BackgroundBrush.Color = Colors.Blue
End Sub
private void setButton2BackgroundBrushColor(object sender, EventArgs e)
{
// This appears to work:
// the brush changes to blue.
Button2BackgroundBrush.Color = Colors.Blue;
}
移除整个演示图板
通过使用 RemoveStoryboard 触发器或 Storyboard.Remove 方法，通知演示图板动画停止影响其目标属性。 此方法与设置 FillBehavior 属性的不同之处在于：您可以在任何时候移除演示图板，而 FillBehavior 属性只有在动画到达其活动期末尾时才有效。
<Button
Name="Button3"
Content="Animate and Then Set Example 3">
<Button.Background>
<SolidColorBrush x:Name="Button3BackgroundBrush"
Color="Red" />
</Button.Background>
<Button.Triggers>
<EventTrigger RoutedEvent="Button.Click">
<BeginStoryboard Name="MyBeginStoryboard">
<Storyboard x:Name="MyStoryboard">
<ColorAnimation
Storyboard.TargetName="Button3BackgroundBrush"
Storyboard.TargetProperty="Color"
From="Red" To="Yellow" Duration="0:0:5"
FillBehavior="HoldEnd"
Completed="setButton3BackgroundBrushColor" />
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Button.Triggers>
</Button>
Private Sub setButton3BackgroundBrushColor(ByVal sender As Object, ByVal e As EventArgs)
' This appears to work:
' the brush changes to blue.
MyStoryboard.Remove(Button3)
Button3BackgroundBrush.Color = Colors.Blue
End Sub
private void setButton3BackgroundBrushColor(object sender, EventArgs e)
{
// This appears to work:
// the brush changes to blue.
MyStoryboard.Remove(Button3);
Button3BackgroundBrush.Color = Colors.Blue;
}
从单个属性移除动画
禁止动画影响属性的另一种方法是使用正在进行动画处理的对象的 BeginAnimation(DependencyProperty, AnimationTimeline) 方法。 将正进行动画处理的属性指定为第一个参数，将 null 指定为第二个参数。
<Button
Name="Button4"
Content="Animate and Then Set Example 4">
<Button.Background>
<SolidColorBrush x:Name="Button4BackgroundBrush"
Color="Red" />
</Button.Background>
<Button.Triggers>
<EventTrigger RoutedEvent="Button.Click">
<BeginStoryboard>
<Storyboard>
<ColorAnimation
Storyboard.TargetName="Button4BackgroundBrush"
Storyboard.TargetProperty="Color"
From="Red" To="Yellow" Duration="0:0:5"
FillBehavior="HoldEnd"
Completed="setButton4BackgroundBrushColor" />
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Button.Triggers>
</Button>
Private Sub setButton4BackgroundBrushColor(ByVal sender As Object, ByVal e As EventArgs)
' This appears to work:
' the brush changes to blue.
Button4BackgroundBrush.BeginAnimation(SolidColorBrush.ColorProperty, Nothing)
Button4BackgroundBrush.Color = Colors.Blue
End Sub
private void setButton4BackgroundBrushColor(object sender, EventArgs e)
{
// This appears to work:
// the brush changes to blue.
Button4BackgroundBrush.BeginAnimation(SolidColorBrush.ColorProperty, null);
Button4BackgroundBrush.Color = Colors.Blue;
}
此方法对于非演示图板动画也有效。