SpringAnimation

Artifact: androidx.dynamicanimation:dynamicanimation

Added in 1.0.0

Kotlin |Java

class SpringAnimation : DynamicAnimation

kotlin.Any
↳	androidx.dynamicanimation.animation.DynamicAnimation
	↳	androidx.dynamicanimation.animation.SpringAnimation

SpringAnimation is an animation that is driven by a SpringForce. The spring force defines the spring's stiffness, damping ratio, as well as the rest position. Once the SpringAnimation is started, on each frame the spring force will update the animation's value and velocity. The animation will continue to run until the spring force reaches equilibrium. If the spring used in the animation is undamped, the animation will never reach equilibrium. Instead, it will oscillate forever.

To create a simple SpringAnimation that uses the default SpringForce:

// Create an animation to animate view's X property, set the rest position of the
// default spring to 0, and start the animation with a starting velocity of 5000 (pixel/s).
final SpringAnimation anim = new SpringAnimation(view, DynamicAnimation.X, 0)
        .setStartVelocity(5000);
anim.start();

Alternatively, a SpringAnimation can take a pre-configured SpringForce, and use that to drive the animation.

// Create a low stiffness, low bounce spring at position 0.
SpringForce spring = new SpringForce(0)
        .setDampingRatio(SpringForce.DAMPING_RATIO_LOW_BOUNCY)
        .setStiffness(SpringForce.STIFFNESS_LOW);
// Create an animation to animate view's scaleY property, and start the animation using
// the spring above and a starting value of 0.5. Additionally, constrain the range of value for
// the animation to be non-negative, effectively preventing any spring overshoot.
final SpringAnimation anim = new SpringAnimation(view, DynamicAnimation.SCALE_Y)
        .setMinValue(0).setSpring(spring).setStartValue(1);
anim.start();

Summary

Public constructors
`SpringAnimation(floatValueHolder: FloatValueHolder!)` This creates a SpringAnimation that animates a `FloatValueHolder` instance.
`SpringAnimation(floatValueHolder: FloatValueHolder!, finalPosition: Float)` This creates a SpringAnimation that animates a `FloatValueHolder` instance.
`<K> SpringAnimation(object: K!, property: FloatPropertyCompat<K!>!)` This creates a SpringAnimation that animates the property of the given object.
`<K> SpringAnimation( object: K!, property: FloatPropertyCompat<K!>!, finalPosition: Float )` This creates a SpringAnimation that animates the property of the given object.

Public functions
`Unit`	`animateToFinalPosition(finalPosition: Float)` Updates the final position of the spring.
`Boolean`	`canSkipToEnd()` Queries whether the spring can eventually come to the rest position.
`Unit`	`@MainThread cancel()` Cancels the on-going animation.
`SpringForce!`	`getSpring()` Returns the spring that the animation uses for animations.
`SpringAnimation!`	`setSpring(force: SpringForce!)` Uses the given spring as the force that drives this animation.
`Unit`	`skipToEnd()` Skips to the end of the animation.
`Unit`	`@MainThread start()` Starts an animation.

Extension functions
`inline SpringAnimation`	`SpringAnimation.withSpringForceProperties(func: SpringForce.() -> Unit)` Updates or applies spring force properties like `SpringForce.mDampingRatio`, `SpringForce.mFinalPosition` and stiffness on SpringAnimation.

Inherited Constants

From androidx.dynamicanimation.animation.DynamicAnimation

`const DynamicAnimation.ViewProperty!`	`ALPHA` View's alpha property.
`const Float`	`MIN_VISIBLE_CHANGE_ALPHA = 0.00390625f` The minimum visible change in alpha that can be visible to users.
`const Float`	`MIN_VISIBLE_CHANGE_PIXELS = 1.0f` The minimum visible change in pixels that can be visible to users.
`const Float`	`MIN_VISIBLE_CHANGE_ROTATION_DEGREES = 0.1f` The minimum visible change in degrees that can be visible to users.
`const Float`	`MIN_VISIBLE_CHANGE_SCALE = 0.002f` The minimum visible change in scale that can be visible to users.
`const DynamicAnimation.ViewProperty!`	`ROTATION` View's rotation property.
`const DynamicAnimation.ViewProperty!`	`ROTATION_X` View's rotationX property.
`const DynamicAnimation.ViewProperty!`	`ROTATION_Y` View's rotationY property.
`const DynamicAnimation.ViewProperty!`	`SCALE_X` View's scaleX property.
`const DynamicAnimation.ViewProperty!`	`SCALE_Y` View's scaleY property.
`const DynamicAnimation.ViewProperty!`	`SCROLL_X` View's scrollX property.
`const DynamicAnimation.ViewProperty!`	`SCROLL_Y` View's scrollY property.
`const DynamicAnimation.ViewProperty!`	`TRANSLATION_X` View's translationX property.
`const DynamicAnimation.ViewProperty!`	`TRANSLATION_Y` View's translationY property.
`const DynamicAnimation.ViewProperty!`	`TRANSLATION_Z` View's translationZ property.
`const DynamicAnimation.ViewProperty!`	`X` View's x property.
`const DynamicAnimation.ViewProperty!`	`Y` View's y property.
`const DynamicAnimation.ViewProperty!`	`Z` View's z property.

Inherited functions

From androidx.dynamicanimation.animation.DynamicAnimation

`T!`	`addEndListener(listener: DynamicAnimation.OnAnimationEndListener!)` Adds an end listener to the animation for receiving onAnimationEnd callbacks.
`T!`	`addUpdateListener(listener: DynamicAnimation.OnAnimationUpdateListener!)` Adds an update listener to the animation for receiving per-frame animation update callbacks.
`Float`	`getMinimumVisibleChange()` Returns the minimum change in the animation property that could be visibly different to users.
`Boolean`	`isRunning()` Returns whether the animation is currently running.
`Unit`	`removeEndListener(listener: DynamicAnimation.OnAnimationEndListener!)` Removes the end listener from the animation, so as to stop receiving animation end callbacks.
`Unit`	`removeUpdateListener( listener: DynamicAnimation.OnAnimationUpdateListener! )` Removes the update listener from the animation, so as to stop receiving animation update callbacks.
`T!`	`setMaxValue(max: Float)` Sets the max value of the animation.
`T!`	`setMinValue(min: Float)` Sets the min value of the animation.
`T!`	`setMinimumVisibleChange( minimumVisibleChange: @FloatRange(from = 0.0, fromInclusive = false) Float )` This method sets the minimal change of animation value that is visible to users, which helps determine a reasonable threshold for the animation's termination condition.
`T!`	`setStartValue(startValue: Float)` Sets the start value of the animation.
`T!`	`setStartVelocity(startVelocity: Float)` Start velocity of the animation.

Public constructors

SpringAnimation

Added in 1.0.0

SpringAnimation(floatValueHolder: FloatValueHolder!)

Note: changing the value in the FloatValueHolder via setValue outside of the animation during an animation run will not have any effect on the on-going animation.

Parameters
`floatValueHolder: FloatValueHolder!`	the property to be animated

SpringAnimation

Added in 1.1.0-alpha04

SpringAnimation(floatValueHolder: FloatValueHolder!, finalPosition: Float)

This creates a SpringAnimation that animates a FloatValueHolder instance. During the animation, the FloatValueHolder instance will be updated via setValue each frame. The caller can obtain the up-to-date animation value via getValue. A Spring will be created with the given final position and default stiffness and damping ratio. This spring can be accessed and reconfigured through setSpring.

Note: changing the value in the FloatValueHolder via setValue outside of the animation during an animation run will not have any effect on the on-going animation.

Parameters
`floatValueHolder: FloatValueHolder!`	the property to be animated
`finalPosition: Float`	the final position of the spring to be created.

SpringAnimation

Added in 1.1.0-alpha04

<K> SpringAnimation(object: K!, property: FloatPropertyCompat<K!>!)

This creates a SpringAnimation that animates the property of the given object. Note, a spring will need to setup through setSpring before the animation starts.

Parameters
`<K>`	the class on which the Property is declared
`object: K!`	the Object whose property will be animated
`property: FloatPropertyCompat<K!>!`	the property to be animated

SpringAnimation

Added in 1.1.0-alpha04

<K> SpringAnimation(
    object: K!,
    property: FloatPropertyCompat<K!>!,
    finalPosition: Float
)

This creates a SpringAnimation that animates the property of the given object. A Spring will be created with the given final position and default stiffness and damping ratio. This spring can be accessed and reconfigured through setSpring.

Parameters
`<K>`	the class on which the Property is declared
`object: K!`	the Object whose property will be animated
`property: FloatPropertyCompat<K!>!`	the property to be animated
`finalPosition: Float`	the final position of the spring to be created.

Public functions

animateToFinalPosition

Added in 1.0.0

fun animateToFinalPosition(finalPosition: Float): Unit

Updates the final position of the spring.

When the animation is running, calling this method would assume the position change of the spring as a continuous movement since last frame, which yields more accurate results than changing the spring position directly through setFinalPosition. If the animation hasn't started, calling this method will change the spring position, and immediately start the animation.

Parameters
`finalPosition: Float`	rest position of the spring

canSkipToEnd

Added in 1.0.0

fun canSkipToEnd(): Boolean

Queries whether the spring can eventually come to the rest position.

Returns
`Boolean`	`true` if the spring is damped, otherwise `false`

cancel

@MainThread
fun cancel(): Unit

Cancels the on-going animation. If the animation hasn't started, no op. Note that this method should only be called on main thread.

Throws
`android.util.AndroidRuntimeException`	if this method is not called on the main thread

getSpring

Added in 1.0.0

fun getSpring(): SpringForce!

Returns the spring that the animation uses for animations.

Returns
`SpringForce!`	the spring that the animation uses for animations

setSpring

Added in 1.0.0

fun setSpring(force: SpringForce!): SpringAnimation!

Uses the given spring as the force that drives this animation. If this spring force has its parameters re-configured during the animation, the new configuration will be reflected in the animation immediately.

Parameters
`force: SpringForce!`	a pre-defined spring force that drives the animation

Returns
`SpringAnimation!`	the animation that the spring force is set on

skipToEnd

Added in 1.0.0

fun skipToEnd(): Unit

Skips to the end of the animation. If the spring is undamped, an IllegalStateException will be thrown, as the animation would never reach to an end. It is recommended to check canSkipToEnd before calling this method. This method should only be called on main thread. If animation is not running, no-op.

Throws
`java.lang.IllegalStateException`	if the spring is undamped (i.e. damping ratio = 0)
`android.util.AndroidRuntimeException`	if this method is not called on the main thread

start

@MainThread
fun start(): Unit

Starts an animation. If the animation has already been started, no op. Note that calling start will not immediately set the property value to start value of the animation. The property values will be changed at each animation pulse, which happens before the draw pass. As a result, the changes will be reflected in the next frame, the same as if the values were set immediately. This method should only be called on main thread.

Throws
`android.util.AndroidRuntimeException`	if this method is not called on the main thread

Extension functions

withSpringForceProperties

Artifact: androidx.dynamicanimation:dynamicanimation-ktx

View Source

inline fun SpringAnimation.withSpringForceProperties(func: SpringForce.() -> Unit): SpringAnimation

Updates or applies spring force properties like SpringForce.mDampingRatio, SpringForce.mFinalPosition and stiffness on SpringAnimation.

If SpringAnimation.mSpring is null in case SpringAnimation is created without final position it will be created and attached to SpringAnimation

Parameters
`func: SpringForce.() -> Unit`	lambda with receiver on `SpringForce`

Returns
`SpringAnimation`	`SpringAnimation`