Článek
11/18/2011

PointAnimation Class

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Animates the value of a Point property between two target values using linear interpolation over a specified Duration.

Inheritance Hierarchy

System.Object
  System.Windows.DependencyObject
    System.Windows.Media.Animation.Timeline
      System.Windows.Media.Animation.PointAnimation

Namespace: System.Windows.Media.Animation
Assembly: System.Windows (in System.Windows.dll)

Syntax

'Declaration
Public NotInheritable Class PointAnimation _
    Inherits Timeline

public sealed class PointAnimation : Timeline

<PointAnimation .../>

The PointAnimation type exposes the following members.

Constructors

	Name	Description
	PointAnimation	Initializes a new instance of the PointAnimation class.

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Properties

	Name	Description
	AutoReverse	Gets or sets a value that indicates whether the timeline plays in reverse after it completes a forward iteration. (Inherited from Timeline.)
	BeginTime	Gets or sets the time at which this Timeline should begin. (Inherited from Timeline.)
	By	Gets or sets the total amount by which the animation changes its starting value.
	Dispatcher	Gets the Dispatcher this object is associated with. (Inherited from DependencyObject.)
	Duration	Gets or sets the length of time for which this timeline plays, not counting repetitions. (Inherited from Timeline.)
	EasingFunction	Gets or sets the easing function you are applying to the animation.
	FillBehavior	Gets or sets a value that specifies how the animation behaves after it reaches the end of its active period. (Inherited from Timeline.)
	From	Gets or sets the animation's starting value.
	RepeatBehavior	Gets or sets the repeating behavior of this timeline. (Inherited from Timeline.)
	SpeedRatio	Gets or sets the rate, relative to its parent, at which time progresses for this Timeline. (Inherited from Timeline.)
	To	Gets or sets the animation's ending value.

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Methods

	Name	Description
	CheckAccess	Determines whether the calling thread has access to this object. (Inherited from DependencyObject.)
	ClearValue	Clears the local value of a dependency property. (Inherited from DependencyObject.)
	Equals(Object)	Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
	GetAnimationBaseValue	Returns any base value established for a Silverlight dependency property, which would apply in cases where an animation is not active. (Inherited from DependencyObject.)
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	GetValue	Returns the current effective value of a dependency property from a DependencyObject. (Inherited from DependencyObject.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	ReadLocalValue	Returns the local value of a dependency property, if a local value is set. (Inherited from DependencyObject.)
	SetValue	Sets the local value of a dependency property on a DependencyObject. (Inherited from DependencyObject.)
	ToString	Returns a string that represents the current object. (Inherited from Object.)

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Events

	Name	Description
	Completed	Occurs when the Storyboard object has completed playing. (Inherited from Timeline.)

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Fields

	Name	Description
	ByProperty	Identifies the By dependency property.
	EasingFunctionProperty	Identifies the EasingFunction dependency property.
	FromProperty	Identifies the From dependency property.
	ToProperty	Identifies the To dependency property.

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Remarks

An animation updates the value of a property over a period of time. An animation effect can be subtle, such as moving a Shape a few pixels left and right, or dramatic, such as enlarging an object to 200 times its original size while spinning it and changing its color. To create an animation, you must associate an animation with an object's property value.

Target Values

The PointAnimation class creates a transition between two target values. To set its target values, use its From, To, and By properties. The following table summarizes how the From, To, and By properties can be used together or separately to determine an animation's target values.

Properties specified	Resulting behavior
From	The animation progresses from the value specified by the From property to the base value of the property being animated or to a previous animation's output value, depending on how the previous animation is configured.
From and To	The animation progresses from the value specified by the From property to the value specified by the To property.
From and By	The animation progresses from the value specified by the From property to the value specified by the sum of the From and By properties.
To	The animation progresses from the animated property's base value or a previous animation's output value to the value specified by the To property.
By	The animation progresses from the base value of the property being animated or a previous animation's output value to the sum of that value and the value specified by the By property.

Note:
If you set both the To and By properties, the To property takes precedence and the By property is ignored.

To use other interpolation methods or animate between more than two target values, use a PointAnimationUsingKeyFrames object.

Examples

The following example shows how to use the PointAnimation to animate the Center property of an EllipseGeometry.

Run this sample

<Canvas Width="450" Height="350">
    <Canvas.Resources>
        <Storyboard x:Name="myStoryboard">

            <!-- Animate the center point of the ellipse from 100 X, 300 Y
             to 400 X, 100 Y over 5 seconds. -->
            <PointAnimation
             Storyboard.TargetProperty="Center"
             Storyboard.TargetName="MyAnimatedEllipseGeometry"
             Duration="0:0:5" 
             From="100,300"
             To="400,100"
             RepeatBehavior="Forever" />

        </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();
}

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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