SpringAnimation

Artifact: androidx.dynamicanimation:dynamicanimation

Added in 1.0.0

Kotlin |Java

public final class SpringAnimation extends DynamicAnimation

java.lang.Object
↳	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, float finalPosition)` This creates a SpringAnimation that animates a `FloatValueHolder` instance.
`<K> SpringAnimation(K object, FloatPropertyCompat<K> property)` This creates a SpringAnimation that animates the property of the given object.
`<K> SpringAnimation( K object, FloatPropertyCompat<K> property, float finalPosition )` This creates a SpringAnimation that animates the property of the given object.

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

Extension functions
`final @NonNull SpringAnimation`	`DynamicAnimationKt.withSpringForceProperties( @NonNull SpringAnimation receiver, @NonNull Function1<@NonNull SpringForce, Unit> func )` Updates or applies spring force properties like `SpringForce.mDampingRatio`, `SpringForce.mFinalPosition` and stiffness on SpringAnimation.

Inherited Constants

From androidx.dynamicanimation.animation.DynamicAnimation

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

Inherited methods

From androidx.dynamicanimation.animation.DynamicAnimation

`T`	`addEndListener(DynamicAnimation.OnAnimationEndListener listener)` Adds an end listener to the animation for receiving onAnimationEnd callbacks.
`T`	`addUpdateListener(DynamicAnimation.OnAnimationUpdateListener listener)` Adds an update listener to the animation for receiving per-frame animation update callbacks.
`@NonNull AnimationHandler`	`@VisibleForTesting getAnimationHandler()` Returns the `AnimationHandler` used to schedule updates for this animator.
`float`	`getMinimumVisibleChange()` Returns the minimum change in the animation property that could be visibly different to users.
`@NonNull FrameCallbackScheduler`	`getScheduler()` Returns the `FrameCallbackScheduler` used to schedule updates for this animator.
`boolean`	`isRunning()` Returns whether the animation is currently running.
`void`	`removeEndListener(DynamicAnimation.OnAnimationEndListener listener)` Removes the end listener from the animation, so as to stop receiving animation end callbacks.
`void`	`removeUpdateListener( DynamicAnimation.OnAnimationUpdateListener listener )` Removes the update listener from the animation, so as to stop receiving animation update callbacks.
`T`	`setMaxValue(float max)` Sets the max value of the animation.
`T`	`setMinValue(float min)` Sets the min value of the animation.
`T`	`setMinimumVisibleChange( @FloatRange(from = 0.0, fromInclusive = false) float minimumVisibleChange )` 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.
`void`	`setScheduler(@NonNull FrameCallbackScheduler scheduler)` Sets the frame scheduler used to schedule updates for this animator.
`T`	`setStartValue(float startValue)` Sets the start value of the animation.
`T`	`setStartVelocity(float startVelocity)` Start velocity of the animation.

Public constructors

SpringAnimation

Added in 1.0.0

public 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

public SpringAnimation(FloatValueHolder floatValueHolder, float finalPosition)

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
`float finalPosition`	the final position of the spring to be created.

SpringAnimation

Added in 1.0.0

public <K> SpringAnimation(K object, FloatPropertyCompat<K> property)

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
`K object`	the Object whose property will be animated
`FloatPropertyCompat<K> property`	the property to be animated

SpringAnimation

Added in 1.0.0

public <K> SpringAnimation(
    K object,
    FloatPropertyCompat<K> property,
    float finalPosition
)

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
`K object`	the Object whose property will be animated
`FloatPropertyCompat<K> property`	the property to be animated
`float finalPosition`	the final position of the spring to be created.

Public methods

animateToFinalPosition

Added in 1.0.0

public void animateToFinalPosition(float finalPosition)

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
`float finalPosition`	rest position of the spring

canSkipToEnd

Added in 1.0.0

public boolean canSkipToEnd()

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

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

cancel

@MainThread
public void cancel()

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

public SpringForce getSpring()

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

public SpringAnimation setSpring(SpringForce force)

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
`SpringForce force`	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

public void skipToEnd()

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. If animation is not running, no-op. Unless a AnimationHandler is provided via setAnimationHandler, a default AnimationHandler is created on the same thread as the first call to start/cancel an animation. All the subsequent animation lifecycle manipulations need to be on that same thread, until the AnimationHandler is reset (using [setAnimationHandler]).

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 same thread as the animation handler

start

@MainThread
public void start()

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. Unless a AnimationHandler is provided via setAnimationHandler, a default AnimationHandler is created on the same thread as the first call to start/cancel an animation. All the subsequent animation lifecycle manipulations need to be on that same thread, until the AnimationHandler is reset (using [setAnimationHandler]).

Throws
`android.util.AndroidRuntimeException`	if this method is not called on the same thread as the animation handler

Extension functions

DynamicAnimationKt.withSpringForceProperties

Artifact: androidx.dynamicanimation:dynamicanimation-ktx

View Source

public final @NonNull SpringAnimation DynamicAnimationKt.withSpringForceProperties(
    @NonNull SpringAnimation receiver,
    @NonNull Function1<@NonNull SpringForce, Unit> func
)

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
`@NonNull Function1<@NonNull SpringForce, Unit> func`	lambda with receiver on `SpringForce`

Returns
`@NonNull SpringAnimation`	`SpringAnimation`