InertiaExpansionBehavior Class
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InertiaExpansionBehavior Class

.NET Framework 4.6 and 4.5

Controls the deceleration of a resizing manipulation during inertia.

Namespace:   System.Windows.Input
Assembly:  PresentationCore (in PresentationCore.dll)


public class InertiaExpansionBehavior


Initializes a new instance of the InertiaExpansionBehavior class.


Gets or sets the rate that resizing slows in device-independent units (1/96th inch per unit) per square milliseconds.


Gets or sets the amount the element resizes at the end of inertia.


Gets or sets the initial average radius.


Gets or sets the initial rate the element resizes at the start of inertia.


Determines whether the specified object is equal to the current object.(Inherited from Object.)


Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)


Serves as the default hash function. (Inherited from Object.)


Gets the Type of the current instance.(Inherited from Object.)


Creates a shallow copy of the current Object.(Inherited from Object.)


Returns a string that represents the current object.(Inherited from Object.)

The InertiaExpansionBehavior class specifies how a expansion manipulation behaves when it is inertia. Use the ExpansionBehavior property in the ManipulationInertiaStarting event to do the following:

  • Specify the initial velocity of the inertia when it begins by setting the InitialVelocity property.

  • Specify the desired expansion of the manipulation when inertia ends by setting the DesiredExpansion property.

  • Specify the desired deceleration of the inertia by setting the DesiredDeceleration property.

Set either the DesiredExpansion or the DesiredDeceleration, but not both. When you set one of these properties, the other property is changed to Double.NaN if it has a value.

For more information about manipulations, see the Input Overview. For an example of an application that responds to manipulations, see Walkthrough: Creating Your First Touch Application.

The following example shows the ManipulationInertiaStarting event handler and sets the desired deceleration for translation, expansion, and rotation that is used during inertia. This example is part of a larger example in Walkthrough: Creating Your First Touch Application.

void Window_InertiaStarting(object sender, ManipulationInertiaStartingEventArgs e)

    // Decrease the velocity of the Rectangle's movement by 
    // 10 inches per second every second.
    // (10 inches * 96 pixels per inch / 1000ms^2)
    e.TranslationBehavior.DesiredDeceleration = 10.0 * 96.0 / (1000.0 * 1000.0);

    // Decrease the velocity of the Rectangle's resizing by 
    // 0.1 inches per second every second.
    // (0.1 inches * 96 pixels per inch / (1000ms^2)
    e.ExpansionBehavior.DesiredDeceleration = 0.1 * 96 / (1000.0 * 1000.0);

    // Decrease the velocity of the Rectangle's rotation rate by 
    // 2 rotations per second every second.
    // (2 * 360 degrees / (1000ms^2)
    e.RotationBehavior.DesiredDeceleration = 720 / (1000.0 * 1000.0);

    e.Handled = true;

.NET Framework
Available since 4.0

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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