ValueAnimator
open class ValueAnimator : Animator
kotlin.Any | ||
↳ | android.animation.Animator | |
↳ | android.animation.ValueAnimator |
This class provides a simple timing engine for running animations which calculate animated values and set them on target objects.
There is a single timing pulse that all animations use. It runs in a custom handler to ensure that property changes happen on the UI thread.
By default, ValueAnimator uses non-linear time interpolation, via the AccelerateDecelerateInterpolator
class, which accelerates into and decelerates out of an animation. This behavior can be changed by calling ValueAnimator#setInterpolator(TimeInterpolator)
.
Animators can be created from either code or resource files. Here is an example of a ValueAnimator resource file:
Starting from API 23, it is also possible to use a combination of PropertyValuesHolder
and Keyframe
resource tags to create a multi-step animation. Note that you can specify explicit fractional values (from 0 to 1) for each keyframe to determine when, in the overall duration, the animation should arrive at that value. Alternatively, you can leave the fractions off and the keyframes will be equally distributed within the total duration:
Summary
Nested classes | |
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abstract |
Implementors of this interface can add themselves as update listeners to an |
abstract |
Listener interface for the system-wide scaling factor for Animator-based animations. |
Constants | |
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static Int |
This value used used with the |
static Int |
When the animation reaches the end and |
static Int |
When the animation reaches the end and |
Inherited constants | |
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Public constructors | |
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Creates a new ValueAnimator object. |
Public methods | |
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open Unit |
Adds a listener to the set of listeners that are sent update events through the life of an animation. |
open static Boolean |
Returns whether animators are currently enabled, system-wide. |
open Unit |
cancel() |
open ValueAnimator |
clone() |
open Unit |
end() |
open Float |
Returns the current animation fraction, which is the elapsed/interpolated fraction used in the most recent frame update on the animation. |
open Any! |
The most recent value calculated by this |
open Any! |
getAnimatedValue(propertyName: String!) The most recent value calculated by this |
open Long |
Gets the current position of the animation in time, which is equal to the current time minus the time that the animation started. |
open Long |
Gets the length of the animation. |
open static Float |
Returns the system-wide scaling factor for Animator-based animations. |
open static Long |
The amount of time, in milliseconds, between each frame of the animation. |
open TimeInterpolator! |
Returns the timing interpolator that this ValueAnimator uses. |
open Int |
Defines how many times the animation should repeat. |
open Int |
Defines what this animation should do when it reaches the end. |
open Long |
The amount of time, in milliseconds, to delay starting the animation after |
open Long | |
open Array<PropertyValuesHolder!>! |
Returns the values that this ValueAnimator animates between. |
open Boolean | |
open Boolean | |
open static ValueAnimator! |
Constructs and returns a ValueAnimator that animates between color values. |
open static ValueAnimator! |
Constructs and returns a ValueAnimator that animates between float values. |
open static ValueAnimator! |
Constructs and returns a ValueAnimator that animates between int values. |
open static ValueAnimator! |
ofObject(evaluator: TypeEvaluator<Any!>!, vararg values: Any!) Constructs and returns a ValueAnimator that animates between Object values. |
open static ValueAnimator! |
ofPropertyValuesHolder(vararg values: PropertyValuesHolder!) Constructs and returns a ValueAnimator that animates between the values specified in the PropertyValuesHolder objects. |
open Unit |
pause() |
open static Boolean |
Registers a |
open Unit |
Removes all listeners from the set listening to frame updates for this animation. |
open Unit |
Removes a listener from the set listening to frame updates for this animation. |
open Unit |
resume() |
open Unit |
reverse() Plays the ValueAnimator in reverse. |
open Unit |
setCurrentFraction(fraction: Float) Sets the position of the animation to the specified fraction. |
open Unit |
setCurrentPlayTime(playTime: Long) Sets the position of the animation to the specified point in time. |
open ValueAnimator! |
setDuration(duration: Long) Sets the length of the animation. |
open Unit |
setEvaluator(value: TypeEvaluator<Any!>!) The type evaluator to be used when calculating the animated values of this animation. |
open Unit |
setFloatValues(vararg values: Float) Sets float values that will be animated between. |
open static Unit |
setFrameDelay(frameDelay: Long) The amount of time, in milliseconds, between each frame of the animation. |
open Unit |
setIntValues(vararg values: Int) Sets int values that will be animated between. |
open Unit |
setInterpolator(value: TimeInterpolator!) The time interpolator used in calculating the elapsed fraction of this animation. |
open Unit |
setObjectValues(vararg values: Any!) Sets the values to animate between for this animation. |
open Unit |
setRepeatCount(value: Int) Sets how many times the animation should be repeated. |
open Unit |
setRepeatMode(value: Int) Defines what this animation should do when it reaches the end. |
open Unit |
setStartDelay(startDelay: Long) The amount of time, in milliseconds, to delay starting the animation after |
open Unit |
setValues(vararg values: PropertyValuesHolder!) Sets the values, per property, being animated between. |
open Unit |
start() |
open String |
toString() |
open static Boolean |
Unregisters a DurationScaleChangeListener. |
Inherited functions | |
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Constants
INFINITE
static val INFINITE: Int
This value used used with the setRepeatCount(int)
property to repeat the animation indefinitely.
Value: -1
RESTART
static val RESTART: Int
When the animation reaches the end and repeatCount
is INFINITE or a positive value, the animation restarts from the beginning.
Value: 1
REVERSE
static val REVERSE: Int
When the animation reaches the end and repeatCount
is INFINITE or a positive value, the animation reverses direction on every iteration.
Value: 2
Public constructors
ValueAnimator
ValueAnimator()
Creates a new ValueAnimator object. This default constructor is primarily for use internally; the factory methods which take parameters are more generally useful.
Public methods
addUpdateListener
open fun addUpdateListener(listener: ValueAnimator.AnimatorUpdateListener!): Unit
Adds a listener to the set of listeners that are sent update events through the life of an animation. This method is called on all listeners for every frame of the animation, after the values for the animation have been calculated.
Parameters | |
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listener |
ValueAnimator.AnimatorUpdateListener!: the listener to be added to the current set of listeners for this animation. |
areAnimatorsEnabled
open static fun areAnimatorsEnabled(): Boolean
Returns whether animators are currently enabled, system-wide. By default, all animators are enabled. This can change if either the user sets a Developer Option to set the animator duration scale to 0 or by Battery Savery mode being enabled (which disables all animations).
Developers should not typically need to call this method, but should an app wish to show a different experience when animators are disabled, this return value can be used as a decider of which experience to offer.
Return | |
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Boolean |
boolean Whether animators are currently enabled. The default value is true . |
clone
open fun clone(): ValueAnimator
Return | |
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ValueAnimator |
a clone of this instance. |
Exceptions | |
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java.lang.CloneNotSupportedException |
if the object's class does not support the Cloneable interface. Subclasses that override the clone method can also throw this exception to indicate that an instance cannot be cloned. |
getAnimatedFraction
open fun getAnimatedFraction(): Float
Returns the current animation fraction, which is the elapsed/interpolated fraction used in the most recent frame update on the animation.
Return | |
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Float |
Elapsed/interpolated fraction of the animation. |
getAnimatedValue
open fun getAnimatedValue(): Any!
The most recent value calculated by this ValueAnimator
when there is just one property being animated. This value is only sensible while the animation is running. The main purpose for this read-only property is to retrieve the value from the ValueAnimator
during a call to AnimatorUpdateListener#onAnimationUpdate(ValueAnimator)
, which is called during each animation frame, immediately after the value is calculated.
Return | |
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Any! |
animatedValue The value most recently calculated by this ValueAnimator for the single property being animated. If there are several properties being animated (specified by several PropertyValuesHolder objects in the constructor), this function returns the animated value for the first of those objects. |
getAnimatedValue
open fun getAnimatedValue(propertyName: String!): Any!
The most recent value calculated by this ValueAnimator
for propertyName
. The main purpose for this read-only property is to retrieve the value from the ValueAnimator
during a call to AnimatorUpdateListener#onAnimationUpdate(ValueAnimator)
, which is called during each animation frame, immediately after the value is calculated.
Return | |
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Any! |
animatedValue The value most recently calculated for the named property by this ValueAnimator . |
getCurrentPlayTime
open fun getCurrentPlayTime(): Long
Gets the current position of the animation in time, which is equal to the current time minus the time that the animation started. An animation that is not yet started will return a value of zero, unless the animation has has its play time set via setCurrentPlayTime(long)
or setCurrentFraction(float)
, in which case it will return the time that was set.
Return | |
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Long |
The current position in time of the animation. |
getDuration
open fun getDuration(): Long
Gets the length of the animation. The default duration is 300 milliseconds.
Return | |
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Long |
The length of the animation, in milliseconds. |
getDurationScale
open static fun getDurationScale(): Float
Returns the system-wide scaling factor for Animator-based animations. This affects both the start delay and duration of all such animations. Setting to 0 will cause animations to end immediately. The default value is 1.0f.
Return | |
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Float |
the duration scale. Value is 0 or greater |
getFrameDelay
open static fun getFrameDelay(): Long
The amount of time, in milliseconds, between each frame of the animation. This is a requested time that the animation will attempt to honor, but the actual delay between frames may be different, depending on system load and capabilities. This is a static function because the same delay will be applied to all animations, since they are all run off of a single timing loop. The frame delay may be ignored when the animation system uses an external timing source, such as the display refresh rate (vsync), to govern animations. Note that this method should be called from the same thread that start()
is called in order to check the frame delay for that animation. A runtime exception will be thrown if the calling thread does not have a Looper.
Return | |
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Long |
the requested time between frames, in milliseconds |
getInterpolator
open fun getInterpolator(): TimeInterpolator!
Returns the timing interpolator that this ValueAnimator uses.
Return | |
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TimeInterpolator! |
The timing interpolator for this ValueAnimator. |
getRepeatCount
open fun getRepeatCount(): Int
Defines how many times the animation should repeat. The default value is 0.
Return | |
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Int |
the number of times the animation should repeat, or INFINITE |
getRepeatMode
open fun getRepeatMode(): Int
Defines what this animation should do when it reaches the end.
Return | |
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Int |
either one of REVERSE or RESTART Value is android.animation.ValueAnimator#RESTART , or android.animation.ValueAnimator#REVERSE |
getStartDelay
open fun getStartDelay(): Long
The amount of time, in milliseconds, to delay starting the animation after start()
is called.
Return | |
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Long |
the number of milliseconds to delay running the animation |
getTotalDuration
open fun getTotalDuration(): Long
Return | |
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Long |
Total time an animation takes to finish, starting from the time start() is called. DURATION_INFINITE will be returned if the animation or any child animation repeats infinite times. |
getValues
open fun getValues(): Array<PropertyValuesHolder!>!
Returns the values that this ValueAnimator animates between. These values are stored in PropertyValuesHolder objects, even if the ValueAnimator was created with a simple list of value objects instead.
Return | |
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Array<PropertyValuesHolder!>! |
PropertyValuesHolder[] An array of PropertyValuesHolder objects which hold the values, per property, that define the animation. |
isRunning
open fun isRunning(): Boolean
Return | |
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Boolean |
Whether the Animator is running. |
isStarted
open fun isStarted(): Boolean
Return | |
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Boolean |
Whether the Animator has been started and not yet ended. |
ofArgb
open static fun ofArgb(vararg values: Int): ValueAnimator!
Constructs and returns a ValueAnimator that animates between color values. A single value implies that that value is the one being animated to. However, this is not typically useful in a ValueAnimator object because there is no way for the object to determine the starting value for the animation (unlike ObjectAnimator, which can derive that value from the target object and property being animated). Therefore, there should typically be two or more values.
Parameters | |
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values |
Int: A set of values that the animation will animate between over time. |
Return | |
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ValueAnimator! |
A ValueAnimator object that is set up to animate between the given values. |
ofFloat
open static fun ofFloat(vararg values: Float): ValueAnimator!
Constructs and returns a ValueAnimator that animates between float values. A single value implies that that value is the one being animated to. However, this is not typically useful in a ValueAnimator object because there is no way for the object to determine the starting value for the animation (unlike ObjectAnimator, which can derive that value from the target object and property being animated). Therefore, there should typically be two or more values.
Parameters | |
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values |
Float: A set of values that the animation will animate between over time. |
Return | |
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ValueAnimator! |
A ValueAnimator object that is set up to animate between the given values. |
ofInt
open static fun ofInt(vararg values: Int): ValueAnimator!
Constructs and returns a ValueAnimator that animates between int values. A single value implies that that value is the one being animated to. However, this is not typically useful in a ValueAnimator object because there is no way for the object to determine the starting value for the animation (unlike ObjectAnimator, which can derive that value from the target object and property being animated). Therefore, there should typically be two or more values.
Parameters | |
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values |
Int: A set of values that the animation will animate between over time. |
Return | |
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ValueAnimator! |
A ValueAnimator object that is set up to animate between the given values. |
ofObject
open static fun ofObject(
evaluator: TypeEvaluator<Any!>!,
vararg values: Any!
): ValueAnimator!
Constructs and returns a ValueAnimator that animates between Object values. A single value implies that that value is the one being animated to. However, this is not typically useful in a ValueAnimator object because there is no way for the object to determine the starting value for the animation (unlike ObjectAnimator, which can derive that value from the target object and property being animated). Therefore, there should typically be two or more values.
Note: The Object values are stored as references to the original objects, which means that changes to those objects after this method is called will affect the values on the animator. If the objects will be mutated externally after this method is called, callers should pass a copy of those objects instead.
Since ValueAnimator does not know how to animate between arbitrary Objects, this factory method also takes a TypeEvaluator object that the ValueAnimator will use to perform that interpolation.
Parameters | |
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evaluator |
TypeEvaluator<Any!>!: A TypeEvaluator that will be called on each animation frame to provide the ncessry interpolation between the Object values to derive the animated value. |
values |
Any!: A set of values that the animation will animate between over time. |
Return | |
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ValueAnimator! |
A ValueAnimator object that is set up to animate between the given values. |
ofPropertyValuesHolder
open static fun ofPropertyValuesHolder(vararg values: PropertyValuesHolder!): ValueAnimator!
Constructs and returns a ValueAnimator that animates between the values specified in the PropertyValuesHolder objects.
Parameters | |
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values |
PropertyValuesHolder!: A set of PropertyValuesHolder objects whose values will be animated between over time. |
Return | |
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ValueAnimator! |
A ValueAnimator object that is set up to animate between the given values. |
registerDurationScaleChangeListener
open static fun registerDurationScaleChangeListener(listener: ValueAnimator.DurationScaleChangeListener): Boolean
Registers a DurationScaleChangeListener
This listens for changes to the system-wide scaling factor for Animator-based animations. Listeners will be called on the main thread.
Parameters | |
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listener |
ValueAnimator.DurationScaleChangeListener: the listener to register. This value cannot be null . |
Return | |
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Boolean |
true if the listener was registered. |
removeAllUpdateListeners
open fun removeAllUpdateListeners(): Unit
Removes all listeners from the set listening to frame updates for this animation.
removeUpdateListener
open fun removeUpdateListener(listener: ValueAnimator.AnimatorUpdateListener!): Unit
Removes a listener from the set listening to frame updates for this animation.
Parameters | |
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listener |
ValueAnimator.AnimatorUpdateListener!: the listener to be removed from the current set of update listeners for this animation. |
reverse
open fun reverse(): Unit
Plays the ValueAnimator in reverse. If the animation is already running, it will stop itself and play backwards from the point reached when reverse was called. If the animation is not currently running, then it will start from the end and play backwards. This behavior is only set for the current animation; future playing of the animation will use the default behavior of playing forward.
setCurrentFraction
open fun setCurrentFraction(fraction: Float): Unit
Sets the position of the animation to the specified fraction. This fraction should be between 0 and the total fraction of the animation, including any repetition. That is, a fraction of 0 will position the animation at the beginning, a value of 1 at the end, and a value of 2 at the end of a reversing animator that repeats once. If the animation has not yet been started, then it will not advance forward after it is set to this fraction; it will simply set the fraction to this value and perform any appropriate actions based on that fraction. If the animation is already running, then setCurrentFraction() will set the current fraction to this value and continue playing from that point. Animator.AnimatorListener
events are not called due to changing the fraction; those events are only processed while the animation is running.
Parameters | |
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fraction |
Float: The fraction to which the animation is advanced or rewound. Values outside the range of 0 to the maximum fraction for the animator will be clamped to the correct range. |
setCurrentPlayTime
open fun setCurrentPlayTime(playTime: Long): Unit
Sets the position of the animation to the specified point in time. This time should be between 0 and the total duration of the animation, including any repetition. If the animation has not yet been started, then it will not advance forward after it is set to this time; it will simply set the time to this value and perform any appropriate actions based on that time. If the animation is already running, then setCurrentPlayTime() will set the current playing time to this value and continue playing from that point.
Parameters | |
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playTime |
Long: The time, in milliseconds, to which the animation is advanced or rewound. |
setDuration
open fun setDuration(duration: Long): ValueAnimator!
Sets the length of the animation. The default duration is 300 milliseconds.
Parameters | |
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duration |
Long: The length of the animation, in milliseconds. This value cannot be negative. |
Return | |
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ValueAnimator! |
ValueAnimator The object called with setDuration(). This return value makes it easier to compose statements together that construct and then set the duration, as in ValueAnimator.ofInt(0, 10).setDuration(500).start() . |
setEvaluator
open fun setEvaluator(value: TypeEvaluator<Any!>!): Unit
The type evaluator to be used when calculating the animated values of this animation. The system will automatically assign a float or int evaluator based on the type of startValue
and endValue
in the constructor. But if these values are not one of these primitive types, or if different evaluation is desired (such as is necessary with int values that represent colors), a custom evaluator needs to be assigned. For example, when running an animation on color values, the ArgbEvaluator
should be used to get correct RGB color interpolation.
If this ValueAnimator has only one set of values being animated between, this evaluator will be used for that set. If there are several sets of values being animated, which is the case if PropertyValuesHolder objects were set on the ValueAnimator, then the evaluator is assigned just to the first PropertyValuesHolder object.
Parameters | |
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value |
TypeEvaluator<Any!>!: the evaluator to be used this animation |
setFloatValues
open fun setFloatValues(vararg values: Float): Unit
Sets float values that will be animated between. A single value implies that that value is the one being animated to. However, this is not typically useful in a ValueAnimator object because there is no way for the object to determine the starting value for the animation (unlike ObjectAnimator, which can derive that value from the target object and property being animated). Therefore, there should typically be two or more values.
If there are already multiple sets of values defined for this ValueAnimator via more than one PropertyValuesHolder object, this method will set the values for the first of those objects.
Parameters | |
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values |
Float: A set of values that the animation will animate between over time. |
setFrameDelay
open static fun setFrameDelay(frameDelay: Long): Unit
The amount of time, in milliseconds, between each frame of the animation. This is a requested time that the animation will attempt to honor, but the actual delay between frames may be different, depending on system load and capabilities. This is a static function because the same delay will be applied to all animations, since they are all run off of a single timing loop. The frame delay may be ignored when the animation system uses an external timing source, such as the display refresh rate (vsync), to govern animations. Note that this method should be called from the same thread that start()
is called in order to have the new frame delay take effect on that animation. A runtime exception will be thrown if the calling thread does not have a Looper.
Parameters | |
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frameDelay |
Long: the requested time between frames, in milliseconds |
setIntValues
open fun setIntValues(vararg values: Int): Unit
Sets int values that will be animated between. A single value implies that that value is the one being animated to. However, this is not typically useful in a ValueAnimator object because there is no way for the object to determine the starting value for the animation (unlike ObjectAnimator, which can derive that value from the target object and property being animated). Therefore, there should typically be two or more values.
If there are already multiple sets of values defined for this ValueAnimator via more than one PropertyValuesHolder object, this method will set the values for the first of those objects.
Parameters | |
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values |
Int: A set of values that the animation will animate between over time. |
setInterpolator
open fun setInterpolator(value: TimeInterpolator!): Unit
The time interpolator used in calculating the elapsed fraction of this animation. The interpolator determines whether the animation runs with linear or non-linear motion, such as acceleration and deceleration. The default value is android.view.animation.AccelerateDecelerateInterpolator
Parameters | |
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value |
TimeInterpolator!: the interpolator to be used by this animation. A value of null will result in linear interpolation. |
setObjectValues
open fun setObjectValues(vararg values: Any!): Unit
Sets the values to animate between for this animation. A single value implies that that value is the one being animated to. However, this is not typically useful in a ValueAnimator object because there is no way for the object to determine the starting value for the animation (unlike ObjectAnimator, which can derive that value from the target object and property being animated). Therefore, there should typically be two or more values.
Note: The Object values are stored as references to the original objects, which means that changes to those objects after this method is called will affect the values on the animator. If the objects will be mutated externally after this method is called, callers should pass a copy of those objects instead.
If there are already multiple sets of values defined for this ValueAnimator via more than one PropertyValuesHolder object, this method will set the values for the first of those objects.
There should be a TypeEvaluator set on the ValueAnimator that knows how to interpolate between these value objects. ValueAnimator only knows how to interpolate between the primitive types specified in the other setValues() methods.
Parameters | |
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values |
Any!: The set of values to animate between. |
setRepeatCount
open fun setRepeatCount(value: Int): Unit
Sets how many times the animation should be repeated. If the repeat count is 0, the animation is never repeated. If the repeat count is greater than 0 or INFINITE
, the repeat mode will be taken into account. The repeat count is 0 by default.
Parameters | |
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value |
Int: the number of times the animation should be repeated |
setRepeatMode
open fun setRepeatMode(value: Int): Unit
Defines what this animation should do when it reaches the end. This setting is applied only when the repeat count is either greater than 0 or INFINITE
. Defaults to RESTART
.
Parameters | |
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value |
Int: RESTART or REVERSE Value is android.animation.ValueAnimator#RESTART , or android.animation.ValueAnimator#REVERSE |
setStartDelay
open fun setStartDelay(startDelay: Long): Unit
The amount of time, in milliseconds, to delay starting the animation after start()
is called. Note that the start delay should always be non-negative. Any negative start delay will be clamped to 0 on N and above.
Parameters | |
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startDelay |
Long: The amount of the delay, in milliseconds |
setValues
open fun setValues(vararg values: PropertyValuesHolder!): Unit
Sets the values, per property, being animated between. This function is called internally by the constructors of ValueAnimator that take a list of values. But a ValueAnimator can be constructed without values and this method can be called to set the values manually instead.
Parameters | |
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values |
PropertyValuesHolder!: The set of values, per property, being animated between. |
toString
open fun toString(): String
Return | |
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String |
a string representation of the object. |
unregisterDurationScaleChangeListener
open static fun unregisterDurationScaleChangeListener(listener: ValueAnimator.DurationScaleChangeListener): Boolean
Unregisters a DurationScaleChangeListener.
Parameters | |
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listener |
ValueAnimator.DurationScaleChangeListener: the listener to unregister. This value cannot be null . |
Return | |
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Boolean |
true if the listener was unregistered. |