Namespace:
System.Windows.Media.Animation
Assembly:
System.Windows (in System.Windows.dll)
Visual Basic (Declaration)
<ContentPropertyAttribute("KeyFrames", True)> _
Public NotInheritable Class PointAnimationUsingKeyFrames _
Inherits Timeline
Dim instance As PointAnimationUsingKeyFrames
[ContentPropertyAttribute("KeyFrames", true)]
public sealed class PointAnimationUsingKeyFrames : Timeline
XAML Object Element Usage
<PointAnimationUsingKeyFrames>
oneOrMorePointKeyFrames
</PointAnimationUsingKeyFrames>
A key frame animation's target values are defined by its KeyFrames property, which contains a collection of PointKeyFrame objects. Each PointKeyFrame defines a segment of the animation with its own target Value and KeyTime. When the animation runs, it progresses from one key value to the next at the specified key times.
There are three types of PointKeyFrame classes, one for each supported interpolation method: LinearPointKeyFrame, DiscretePointKeyFrame, and SplinePointKeyFrame.
Unlike a PointAnimation, a PointAnimationUsingKeyFrames can have more than two target values. You can also control the interpolation method of individual PointKeyFrame segments.
When declaring a PointAnimationUsingKeyFrames in XAML, the order of the PointKeyFrame object elements is not significant, because the KeyTime controls the timing and therefore the order in which the key frames are executed. However, it is good markup style to keep the element order the same as the KeyTime sequence order.
The following example moves an ellipse along a triangular path. The example uses the PointAnimationUsingKeyFrames class to animate the Center property of an EllipseGeometry. This animation uses three key frames in the following manner:
During the first half second, it uses an instance of the LinearPointKeyFrame class to move the ellipse along a path at a steady rate from its starting position. Linear key frames such as LinearPointKeyFrame create a smooth linear interpolation between values.
During the end of the next half second, it uses an instance of the DiscretePointKeyFrame class to suddenly move the ellipse along the path to the next position. Discrete key frames like DiscretePointKeyFrame create sudden jumps between values.
During the final two seconds, it uses an instance of the SplinePointKeyFrame class to move the ellipse back to its starting position. Spline key frames like SplinePointKeyFrame create a variable transition between values according to the values of the KeySpline property. In this example, the animation begins slowly and speeds up exponentially toward the end of the time segment.
Run this sample
<Canvas Width="400" Height="300">
<Canvas.Resources>
<Storyboard x:Name="myStoryboard">
<!-- Animating the Center property uses 3 KeyFrames, which animate
the ellipse allong a triangular path. -->
<PointAnimationUsingKeyFrames
Storyboard.TargetProperty="Center"
Storyboard.TargetName="MyAnimatedEllipseGeometry"
Duration="0:0:5" RepeatBehavior="Forever">
<!-- Over the first half second, Using a LinearPointKeyFrame, the ellipse
moves steadily from its starting position along the first line of the
trianglar path. -->
<LinearPointKeyFrame KeyTime="0:0:0.5" Value="100,300" />
<!-- Using a DiscretePointKeyFrame, the ellipse suddenly changes position
after the first second of the animation. -->
<DiscretePointKeyFrame KeyTime="0:0:1" Value="400,300" />
<!-- Using a SplinePointKeyFrame, the ellipse moves back to its starting
position. It moves slowly at first and then speeds up. This key frame
takes 2 seconds to complete. -->
<SplinePointKeyFrame KeySpline="0.6,0.0 0.9,0.00"
KeyTime="0:0:3" Value="200,100" />
</PointAnimationUsingKeyFrames>
</Storyboard>
</Canvas.Resources>
<Path Fill="Blue" Loaded="Start_Animation">
<Path.Data>
<!-- Describes an ellipse. -->
<EllipseGeometry x:Name="MyAnimatedEllipseGeometry"
Center="200,100" RadiusX="15" RadiusY="15" />
</Path.Data>
</Path>
</Canvas>
' Start the animation when the object loads
Private Sub Start_Animation(ByVal sender As Object, ByVal e As EventArgs)
myStoryboard.Begin()
End Sub
// Start the animation when the object loads
private void Start_Animation(object sender, EventArgs e)
{
myStoryboard.Begin();
}
System..::.Object
System.Windows..::.DependencyObject
System.Windows.Media.Animation..::.Timeline
System.Windows.Media.Animation..::.PointAnimationUsingKeyFrames
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.
Reference
Other Resources