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BackEase Class

Represents an easing function that retracts the motion of an animation slightly before it begins to animate in the path indicated.

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

'Declaration
Public Class BackEase _
	Inherits EasingFunctionBase

The BackEase type exposes the following members.

  NameDescription
Public methodSupported by Silverlight for Windows PhoneBackEaseInitializes a new instance of the BackEase class.
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  NameDescription
Public propertySupported by Silverlight for Windows PhoneAmplitudeGets or sets the amplitude of retraction associated with a BackEase animation.
Public propertySupported by Silverlight for Windows PhoneDispatcherGets the Dispatcher this object is associated with. (Inherited from DependencyObject.)
Public propertySupported by Silverlight for Windows PhoneEasingModeGets or sets a value that specifies how the animation interpolates. (Inherited from EasingFunctionBase.)
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  NameDescription
Public methodSupported by Silverlight for Windows PhoneCheckAccessDetermines whether the calling thread has access to this object. (Inherited from DependencyObject.)
Public methodSupported by Silverlight for Windows PhoneClearValueClears the local value of a dependency property. (Inherited from DependencyObject.)
Public methodSupported by Silverlight for Windows PhoneEaseTransforms normalized time to control the pace of an animation. (Inherited from EasingFunctionBase.)
Protected methodSupported by Silverlight for Windows PhoneEaseInCoreProvides the logic portion of the easing function that you can override to produce the EaseIn mode of the custom easing function. (Overrides EasingFunctionBase.EaseInCore(Double).)
Public methodSupported by Silverlight for Windows PhoneEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodSupported by Silverlight for Windows PhoneFinalizeAllows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
Public methodSupported by Silverlight for Windows PhoneGetAnimationBaseValueReturns any base value established for a Silverlight dependency property, which would apply in cases where an animation is not active. (Inherited from DependencyObject.)
Public methodSupported by Silverlight for Windows PhoneGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodSupported by Silverlight for Windows PhoneGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodSupported by Silverlight for Windows PhoneGetValueReturns the current effective value of a dependency property from a DependencyObject. (Inherited from DependencyObject.)
Protected methodSupported by Silverlight for Windows PhoneMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodSupported by Silverlight for Windows PhoneReadLocalValueReturns the local value of a dependency property, if a local value is set. (Inherited from DependencyObject.)
Public methodSupported by Silverlight for Windows PhoneSetValueSets the local value of a dependency property on a DependencyObject. (Inherited from DependencyObject.)
Public methodSupported by Silverlight for Windows PhoneToStringReturns a string that represents the current object. (Inherited from Object.)
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  NameDescription
Public fieldStatic memberSupported by Silverlight for Windows PhoneAmplitudePropertyIdentifies the Amplitude dependency property.
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You can control when the "back up" behavior occurs in an animation by specifying the EasingMode property value on an animation. The following graph demonstrate the different values of EasingMode, where f(t) represents the animation progress and t represents time.

BackEase EasingMode graphs.

The formula used for this function is the following.

BackEase formula.
NoteNote:

Because this animation causes values to retract before progressing, the animation might interpolate into negative numbers unexpectedly. This can cause errors when animating properties that do not allow negative numbers. For example, if you apply this animation to the Height of an object (e.g. from 0 to 200 with an EasingMode of EaseIn), the animation will attempt to interpolate through negative numbers for Height which will throw an error.

There are several other easing functions besides BackEase, which you can explore using the following sample.

Run this sample

In addition to using the easing functions included in the run-time, you can create your own custom easing functions by inheriting from EasingFunctionBase.

The following example applies a BackEase easing function to a DoubleAnimation to create an animation that retracts slightly at the beginning and end of the animation.

Run this sample


<StackPanel x:Name="LayoutRoot" Background="White">
    <StackPanel.Resources>
        <Storyboard x:Name="myStoryboard">
            <DoubleAnimation From="1" To="2" Duration="00:00:1" 
                Storyboard.TargetName="myScaleTransform" 
                Storyboard.TargetProperty="ScaleX">
                <DoubleAnimation.EasingFunction>
                    <BackEase Amplitude="0.3" EasingMode="EaseInOut" />
                </DoubleAnimation.EasingFunction>
            </DoubleAnimation>
            <DoubleAnimation From="1" To="2" Duration="00:00:1" 
                Storyboard.TargetName="myScaleTransform" 
                Storyboard.TargetProperty="ScaleY">
                <DoubleAnimation.EasingFunction>
                    <BackEase Amplitude="0.3" EasingMode="EaseInOut" />
                </DoubleAnimation.EasingFunction>
            </DoubleAnimation>
        </Storyboard>
    </StackPanel.Resources>

    <Rectangle Margin="60" x:Name="myRectangle" MouseLeftButtonDown="Mouse_Clicked" 
     Fill="Blue" Width="50" Height="50" >

        <Rectangle.RenderTransform>
            <ScaleTransform x:Name="myScaleTransform" />
        </Rectangle.RenderTransform>

    </Rectangle>
</StackPanel>



' When the user clicks the rectangle, the animation
' begins. 
Private Sub Mouse_Clicked(ByVal sender As Object, ByVal e As MouseEventArgs)
    myStoryboard.Begin()
End Sub


Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

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

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

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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