Path Animations
A path animation lets you animate an object so that its position
follows a path defined by a PathGeometry. This is often a more convenient
way of defining the motion of an object than using keyframe
animations.
DoubleAnimationUsingPath,
MatrixAnimationUsingPath, and
PointAnimationUsingPath are the three
path animation types. As their names suggest, they can target properties
of type Double, Matrix, and Point, respectively.
PointAnimationUsingPath is the
most straightforward type. It targets a property of type Point, and it will move the location of that
point along the path described by the animation's PathGeometry property. Example 16-29 shows this technique being used to
animate one end of a LineGeometry.
Example 16-29. Point path animation
<Path Stroke="Black" StrokeThickness="4">
<Path.Data>
<LineGeometry StartPoint="50,50" EndPoint="0,0" />
</Path.Data>
<Path.Triggers>
<EventTrigger RoutedEvent="Path.Loaded">
<BeginStoryboard>
<Storyboard>
<PointAnimationUsingPath AutoReverse="True"
RepeatBehavior="Forever" Duration="0:0:2"
Storyboard.TargetProperty="(Path.Data).(LineGeometry.EndPoint)">
<PointAnimationUsingPath.PathGeometry>
<PathGeometry Figures="M 14.64,14.64 A 50,50 90, 0 1 85.36,14.64" />
</PointAnimationUsingPath.PathGeometry>
</PointAnimationUsingPath>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Path.Triggers>
</Path>The PathGeometry describing the animation path contains a single elliptical arc segment. This sweeps out a 90 degree angle, and ...