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Keyframe

public abstract class Keyframe
extends Object implements Cloneable

java.lang.Object
   ↳ android.animation.Keyframe


This class holds a time/value pair for an animation. The Keyframe class is used by ValueAnimator to define the values that the animation target will have over the course of the animation. As the time proceeds from one keyframe to the other, the value of the target object will animate between the value at the previous keyframe and the value at the next keyframe. Each keyframe also holds an optional TimeInterpolator object, which defines the time interpolation over the intervalue preceding the keyframe.

The Keyframe class itself is abstract. The type-specific factory methods will return a subclass of Keyframe specific to the type of value being stored. This is done to improve performance when dealing with the most common cases (e.g., float and int values). Other types will fall into a more general Keyframe class that treats its values as Objects. Unless your animation requires dealing with a custom type or a data structure that needs to be animated directly (and evaluated using an implementation of TypeEvaluator), you should stick to using float and int as animations using those types have lower runtime overhead than other types.

Summary

Public constructors

Keyframe()

Public methods

abstract Keyframe clone()

Creates and returns a copy of this object.

float getFraction()

Gets the time for this keyframe, as a fraction of the overall animation duration.

TimeInterpolator getInterpolator()

Gets the optional interpolator for this Keyframe.

Class getType()

Gets the type of keyframe.

abstract Object getValue()

Gets the value for this Keyframe.

boolean hasValue()

Indicates whether this keyframe has a valid value.

static Keyframe ofFloat(float fraction)

Constructs a Keyframe object with the given time.

static Keyframe ofFloat(float fraction, float value)

Constructs a Keyframe object with the given time and value.

static Keyframe ofInt(float fraction, int value)

Constructs a Keyframe object with the given time and value.

static Keyframe ofInt(float fraction)

Constructs a Keyframe object with the given time.

static Keyframe ofObject(float fraction, Object value)

Constructs a Keyframe object with the given time and value.

static Keyframe ofObject(float fraction)

Constructs a Keyframe object with the given time.

void setFraction(float fraction)

Sets the time for this keyframe, as a fraction of the overall animation duration.

void setInterpolator(TimeInterpolator interpolator)

Sets the optional interpolator for this Keyframe.

abstract void setValue(Object value)

Sets the value for this Keyframe.

Inherited methods

From class java.lang.Object

Public constructors

Keyframe

Added in API level 11
Keyframe ()

Public methods

clone

Added in API level 11
Keyframe clone ()

Creates and returns a copy of this object. The precise meaning of "copy" may depend on the class of the object. The general intent is that, for any object x, the expression:

 x.clone() != x
will be true, and that the expression:
 x.clone().getClass() == x.getClass()
will be true, but these are not absolute requirements. While it is typically the case that:
 x.clone().equals(x)
will be true, this is not an absolute requirement.

By convention, the returned object should be obtained by calling super.clone. If a class and all of its superclasses (except Object) obey this convention, it will be the case that x.clone().getClass() == x.getClass().

By convention, the object returned by this method should be independent of this object (which is being cloned). To achieve this independence, it may be necessary to modify one or more fields of the object returned by super.clone before returning it. Typically, this means copying any mutable objects that comprise the internal "deep structure" of the object being cloned and replacing the references to these objects with references to the copies. If a class contains only primitive fields or references to immutable objects, then it is usually the case that no fields in the object returned by super.clone need to be modified.

The method clone for class Object performs a specific cloning operation. First, if the class of this object does not implement the interface Cloneable, then a CloneNotSupportedException is thrown. Note that all arrays are considered to implement the interface Cloneable and that the return type of the clone method of an array type T[] is T[] where T is any reference or primitive type. Otherwise, this method creates a new instance of the class of this object and initializes all its fields with exactly the contents of the corresponding fields of this object, as if by assignment; the contents of the fields are not themselves cloned. Thus, this method performs a "shallow copy" of this object, not a "deep copy" operation.

The class Object does not itself implement the interface Cloneable, so calling the clone method on an object whose class is Object will result in throwing an exception at run time.

Returns
Keyframe a clone of this instance.

getFraction

Added in API level 11
float getFraction ()

Gets the time for this keyframe, as a fraction of the overall animation duration.

Returns
float The time associated with this keyframe, as a fraction of the overall animation duration. This should be a value between 0 and 1.

getInterpolator

Added in API level 11
TimeInterpolator getInterpolator ()

Gets the optional interpolator for this Keyframe. A value of null indicates that there is no interpolation, which is the same as linear interpolation.

Returns
TimeInterpolator The optional interpolator for this Keyframe.

getType

Added in API level 11
Class getType ()

Gets the type of keyframe. This information is used by ValueAnimator to determine the type of TypeEvaluator to use when calculating values between keyframes. The type is based on the type of Keyframe created.

Returns
Class The type of the value stored in the Keyframe.

getValue

Added in API level 11
Object getValue ()

Gets the value for this Keyframe.

Returns
Object The value for this Keyframe.

hasValue

Added in API level 11
boolean hasValue ()

Indicates whether this keyframe has a valid value. This method is called internally when an ObjectAnimator first starts; keyframes without values are assigned values at that time by deriving the value for the property from the target object.

Returns
boolean boolean Whether this object has a value assigned.

ofFloat

Added in API level 11
Keyframe ofFloat (float fraction)

Constructs a Keyframe object with the given time. The value at this time will be derived from the target object when the animation first starts (note that this implies that keyframes with no initial value must be used as part of an ObjectAnimator). The time defines the time, as a proportion of an overall animation's duration, at which the value will hold true for the animation. The value for the animation between keyframes will be calculated as an interpolation between the values at those keyframes.

Parameters
fraction float: The time, expressed as a value between 0 and 1, representing the fraction of time elapsed of the overall animation duration.
Returns
Keyframe

ofFloat

Added in API level 11
Keyframe ofFloat (float fraction, 
                float value)

Constructs a Keyframe object with the given time and value. The time defines the time, as a proportion of an overall animation's duration, at which the value will hold true for the animation. The value for the animation between keyframes will be calculated as an interpolation between the values at those keyframes.

Parameters
fraction float: The time, expressed as a value between 0 and 1, representing the fraction of time elapsed of the overall animation duration.
value float: The value that the object will animate to as the animation time approaches the time in this keyframe, and the the value animated from as the time passes the time in this keyframe.
Returns
Keyframe

ofInt

Added in API level 11
Keyframe ofInt (float fraction, 
                int value)

Constructs a Keyframe object with the given time and value. The time defines the time, as a proportion of an overall animation's duration, at which the value will hold true for the animation. The value for the animation between keyframes will be calculated as an interpolation between the values at those keyframes.

Parameters
fraction float: The time, expressed as a value between 0 and 1, representing the fraction of time elapsed of the overall animation duration.
value int: The value that the object will animate to as the animation time approaches the time in this keyframe, and the the value animated from as the time passes the time in this keyframe.
Returns
Keyframe

ofInt

Added in API level 11
Keyframe ofInt (float fraction)

Constructs a Keyframe object with the given time. The value at this time will be derived from the target object when the animation first starts (note that this implies that keyframes with no initial value must be used as part of an ObjectAnimator). The time defines the time, as a proportion of an overall animation's duration, at which the value will hold true for the animation. The value for the animation between keyframes will be calculated as an interpolation between the values at those keyframes.

Parameters
fraction float: The time, expressed as a value between 0 and 1, representing the fraction of time elapsed of the overall animation duration.
Returns
Keyframe

ofObject

Added in API level 11
Keyframe ofObject (float fraction, 
                Object value)

Constructs a Keyframe object with the given time and value. The time defines the time, as a proportion of an overall animation's duration, at which the value will hold true for the animation. The value for the animation between keyframes will be calculated as an interpolation between the values at those keyframes.

Parameters
fraction float: The time, expressed as a value between 0 and 1, representing the fraction of time elapsed of the overall animation duration.
value Object: The value that the object will animate to as the animation time approaches the time in this keyframe, and the the value animated from as the time passes the time in this keyframe.
Returns
Keyframe

ofObject

Added in API level 11
Keyframe ofObject (float fraction)

Constructs a Keyframe object with the given time. The value at this time will be derived from the target object when the animation first starts (note that this implies that keyframes with no initial value must be used as part of an ObjectAnimator). The time defines the time, as a proportion of an overall animation's duration, at which the value will hold true for the animation. The value for the animation between keyframes will be calculated as an interpolation between the values at those keyframes.

Parameters
fraction float: The time, expressed as a value between 0 and 1, representing the fraction of time elapsed of the overall animation duration.
Returns
Keyframe

setFraction

Added in API level 11
void setFraction (float fraction)

Sets the time for this keyframe, as a fraction of the overall animation duration.

Parameters
fraction float: time associated with this keyframe, as a fraction of the overall animation duration. This should be a value between 0 and 1.

setInterpolator

Added in API level 11
void setInterpolator (TimeInterpolator interpolator)

Sets the optional interpolator for this Keyframe. A value of null indicates that there is no interpolation, which is the same as linear interpolation.

Parameters
interpolator TimeInterpolator
Returns
void The optional interpolator for this Keyframe.

setValue

Added in API level 11
void setValue (Object value)

Sets the value for this Keyframe.

Parameters
value Object: value for this Keyframe.
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