DynamicAnimation

abstract class DynamicAnimation<T : DynamicAnimation<T!>?>

Known direct subclasses
FlingAnimation

Fling animation is an animation that continues an initial momentum (most often from gesture velocity) and gradually slows down.

SpringAnimation

SpringAnimation is an animation that is driven by a SpringForce.


This class is the base class of physics-based animations. It manages the animation's lifecycle such as start and cancel. This base class also handles the common setup for all the subclass animations. For example, DynamicAnimation supports adding OnAnimationEndListener and OnAnimationUpdateListener so that the important animation events can be observed through the callbacks. The start conditions for any subclass of DynamicAnimation can be set using setStartValue and setStartVelocity.

Parameters
<T : DynamicAnimation<T!>?>

subclass of DynamicAnimation

Summary

Nested types

An animation listener that receives end notifications from an animation.

Implementors of this interface can add themselves as update listeners to an DynamicAnimation instance to receive callbacks on every animation frame, after the current frame's values have been calculated for that DynamicAnimation.

ViewProperty holds the access of a property of a View.

Constants

const DynamicAnimation.ViewProperty!

View's alpha property.

const Float

The minimum visible change in alpha that can be visible to users.

const Float

The minimum visible change in pixels that can be visible to users.

const Float

The minimum visible change in degrees that can be visible to users.

const Float

The minimum visible change in scale that can be visible to users.

const DynamicAnimation.ViewProperty!

View's rotation property.

const DynamicAnimation.ViewProperty!

View's rotationX property.

const DynamicAnimation.ViewProperty!

View's rotationY property.

const DynamicAnimation.ViewProperty!

View's scaleX property.

const DynamicAnimation.ViewProperty!

View's scaleY property.

const DynamicAnimation.ViewProperty!

View's scrollX property.

const DynamicAnimation.ViewProperty!

View's scrollY property.

const DynamicAnimation.ViewProperty!

View's translationX property.

const DynamicAnimation.ViewProperty!

View's translationY property.

const DynamicAnimation.ViewProperty!

View's translationZ property.

const DynamicAnimation.ViewProperty!

View's x property.

const DynamicAnimation.ViewProperty!

View's y property.

const DynamicAnimation.ViewProperty!

View's z property.

Public functions

T!

Adds an end listener to the animation for receiving onAnimationEnd callbacks.

T!

Adds an update listener to the animation for receiving per-frame animation update callbacks.

Unit

Cancels the on-going animation.

Float

Returns the minimum change in the animation property that could be visibly different to users.

Boolean

Returns whether the animation is currently running.

Unit

Removes the end listener from the animation, so as to stop receiving animation end callbacks.

Unit

Removes the update listener from the animation, so as to stop receiving animation update callbacks.

T!

Sets the max value of the animation.

T!

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.

Unit

Starts an animation.

Constants

ALPHA

Added in 1.0.0
const val ALPHADynamicAnimation.ViewProperty!

View's alpha property.

MIN_VISIBLE_CHANGE_ALPHA

Added in 1.0.0
const val MIN_VISIBLE_CHANGE_ALPHA = 0.00390625f: Float

The minimum visible change in alpha that can be visible to users.

MIN_VISIBLE_CHANGE_PIXELS

Added in 1.0.0
const val MIN_VISIBLE_CHANGE_PIXELS = 1.0f: Float

The minimum visible change in pixels that can be visible to users.

MIN_VISIBLE_CHANGE_ROTATION_DEGREES

Added in 1.0.0
const val MIN_VISIBLE_CHANGE_ROTATION_DEGREES = 0.1f: Float

The minimum visible change in degrees that can be visible to users.

MIN_VISIBLE_CHANGE_SCALE

Added in 1.0.0
const val MIN_VISIBLE_CHANGE_SCALE = 0.002f: Float

The minimum visible change in scale that can be visible to users.

ROTATION

Added in 1.0.0
const val ROTATIONDynamicAnimation.ViewProperty!

View's rotation property.

ROTATION_X

Added in 1.0.0
const val ROTATION_XDynamicAnimation.ViewProperty!

View's rotationX property.

ROTATION_Y

Added in 1.0.0
const val ROTATION_YDynamicAnimation.ViewProperty!

View's rotationY property.

SCALE_X

Added in 1.0.0
const val SCALE_XDynamicAnimation.ViewProperty!

View's scaleX property.

SCALE_Y

Added in 1.0.0
const val SCALE_YDynamicAnimation.ViewProperty!

View's scaleY property.

SCROLL_X

Added in 1.0.0
const val SCROLL_XDynamicAnimation.ViewProperty!

View's scrollX property.

SCROLL_Y

Added in 1.0.0
const val SCROLL_YDynamicAnimation.ViewProperty!

View's scrollY property.

TRANSLATION_X

Added in 1.0.0
const val TRANSLATION_XDynamicAnimation.ViewProperty!

View's translationX property.

TRANSLATION_Y

Added in 1.0.0
const val TRANSLATION_YDynamicAnimation.ViewProperty!

View's translationY property.

TRANSLATION_Z

Added in 1.0.0
const val TRANSLATION_ZDynamicAnimation.ViewProperty!

View's translationZ property.

X

Added in 1.0.0
const val XDynamicAnimation.ViewProperty!

View's x property.

Y

Added in 1.0.0
const val YDynamicAnimation.ViewProperty!

View's y property.

Z

Added in 1.0.0
const val ZDynamicAnimation.ViewProperty!

View's z property.

Public functions

addEndListener

Added in 1.0.0
fun addEndListener(listener: DynamicAnimation.OnAnimationEndListener!): T!

Adds an end listener to the animation for receiving onAnimationEnd callbacks. If the listener is null or has already been added to the list of listeners for the animation, no op.

Parameters
listener: DynamicAnimation.OnAnimationEndListener!

the listener to be added

Returns
T!

the animation to which the listener is added

addUpdateListener

Added in 1.0.0
fun addUpdateListener(listener: DynamicAnimation.OnAnimationUpdateListener!): T!

Adds an update listener to the animation for receiving per-frame animation update callbacks. If the listener is null or has already been added to the list of listeners for the animation, no op.

Note that update listener should only be added before the start of the animation.

Parameters
listener: DynamicAnimation.OnAnimationUpdateListener!

the listener to be added

Returns
T!

the animation to which the listener is added

Throws
java.lang.UnsupportedOperationException

if the update listener is added after the animation has started

cancel

Added in 1.0.0
@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

getMinimumVisibleChange

Added in 1.0.0
fun getMinimumVisibleChange(): Float

Returns the minimum change in the animation property that could be visibly different to users.

Returns
Float

minimum change in property value that is visible to users

isRunning

Added in 1.0.0
fun isRunning(): Boolean

Returns whether the animation is currently running.

Returns
Boolean

true if the animation is currently running, false otherwise

removeEndListener

Added in 1.0.0
fun removeEndListener(listener: DynamicAnimation.OnAnimationEndListener!): Unit

Removes the end listener from the animation, so as to stop receiving animation end callbacks.

Parameters
listener: DynamicAnimation.OnAnimationEndListener!

the listener to be removed

removeUpdateListener

Added in 1.0.0
fun removeUpdateListener(
    listener: DynamicAnimation.OnAnimationUpdateListener!
): Unit

Removes the update listener from the animation, so as to stop receiving animation update callbacks.

Parameters
listener: DynamicAnimation.OnAnimationUpdateListener!

the listener to be removed

setMaxValue

Added in 1.0.0
fun setMaxValue(max: Float): T!

Sets the max value of the animation. Animations will not animate beyond their max value. Whether or not animation will come to an end when max value is reached is dependent on the child animation's implementation.

Parameters
max: Float

maximum value of the property to be animated

Returns
T!

the Animation whose max value is being set

setMinValue

Added in 1.0.0
fun setMinValue(min: Float): T!

Sets the min value of the animation. Animations will not animate beyond their min value. Whether or not animation will come to an end when min value is reached is dependent on the child animation's implementation.

Parameters
min: Float

minimum value of the property to be animated

Returns
T!

the Animation whose min value is being set

setMinimumVisibleChange

Added in 1.0.0
fun setMinimumVisibleChange(
    minimumVisibleChange: @FloatRange(from = 0.0, fromInclusive = false) Float
): T!

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. It is critical to set the minimal visible change for custom properties (i.e. non-ViewPropertys) unless the custom property is in pixels.

For custom properties, this minimum visible change defaults to change in pixel (i.e. MIN_VISIBLE_CHANGE_PIXELS. It is recommended to adjust this value that is reasonable for the property to be animated. A general rule of thumb to calculate such a value is: minimum visible change = range of custom property value / corresponding pixel range. For example, if the property to be animated is a progress (from 0 to 100) that corresponds to a 200-pixel change. Then the min visible change should be 100 / 200. (i.e. 0.5).

It's not necessary to call this method when animating ViewPropertys, as the minimum visible change will be derived from the property. For example, if the property to be animated is in pixels (i.e. TRANSLATION_X, TRANSLATION_Y, TRANSLATION_Z, @SCROLL_X or SCROLL_Y), the default minimum visible change is 1 (pixel). For ROTATION, ROTATION_X or ROTATION_Y, the animation will use MIN_VISIBLE_CHANGE_ROTATION_DEGREES as the min visible change, which is 1/10. Similarly, the minimum visible change for alpha ( i.e. MIN_VISIBLE_CHANGE_ALPHA is defined as 1 / 256.

Parameters
minimumVisibleChange: @FloatRange(from = 0.0, fromInclusive = false) Float

minimum change in property value that is visible to users

Returns
T!

the animation whose min visible change is being set

Throws
java.lang.IllegalArgumentException

if the given threshold is not positive

setStartValue

Added in 1.0.0
fun setStartValue(startValue: Float): T!

Sets the start value of the animation. If start value is not set, the animation will get the current value for the view's property, and use that as the start value.

Parameters
startValue: Float

start value for the animation

Returns
T!

the Animation whose start value is being set

setStartVelocity

Added in 1.0.0
fun setStartVelocity(startVelocity: Float): T!

Start velocity of the animation. Default velocity is 0. Unit: change in property per second (e.g. pixels per second, scale/alpha value change per second).

Note when using a fixed value as the start velocity (as opposed to getting the velocity through touch events), it is recommended to define such a value in dp/second and convert it to pixel/second based on the density of the screen to achieve a consistent look across different screens.

To convert from dp/second to pixel/second:

float pixelPerSecond = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dpPerSecond,
        getResources().getDisplayMetrics());
Parameters
startVelocity: Float

start velocity of the animation

Returns
T!

the Animation whose start velocity is being set

start

Added in 1.0.0
@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