Android APIs
public abstract class

Keyframe

extends Object
implements Cloneable
java.lang.Object
   ↳ android.animation.Keyframe

Class Overview

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, float value)
Constructs a Keyframe object with the given time and value.
static Keyframe ofFloat(float fraction)
Constructs a Keyframe object with the given time.
static Keyframe ofInt(float fraction)
Constructs a Keyframe object with the given time.
static Keyframe ofInt(float fraction, int value)
Constructs a Keyframe object with the given time and value.
static Keyframe ofObject(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.
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.
[Expand]
Inherited Methods
From class java.lang.Object

Public Constructors

public Keyframe ()

Added in API level 11

Public Methods

public abstract Keyframe clone ()

Added in API level 11

Creates and returns a copy of this Object. The default implementation returns a so-called "shallow" copy: It creates a new instance of the same class and then copies the field values (including object references) from this instance to the new instance. A "deep" copy, in contrast, would also recursively clone nested objects. A subclass that needs to implement this kind of cloning should call super.clone() to create the new instance and then create deep copies of the nested, mutable objects.

Returns
Keyframe a copy of this object.

public float getFraction ()

Added in API level 11

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.

public TimeInterpolator getInterpolator ()

Added in API level 11

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.

public Class getType ()

Added in API level 11

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.

public abstract Object getValue ()

Added in API level 11

Gets the value for this Keyframe.

Returns
Object The value for this Keyframe.

public boolean hasValue ()

Added in API level 11

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.

public static Keyframe ofFloat (float fraction, float value)

Added in API level 11

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

public static Keyframe ofFloat (float fraction)

Added in API level 11

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

public static Keyframe ofInt (float fraction)

Added in API level 11

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

public static Keyframe ofInt (float fraction, int value)

Added in API level 11

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

public static Keyframe ofObject (float fraction)

Added in API level 11

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

public static Keyframe ofObject (float fraction, Object value)

Added in API level 11

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

public void setFraction (float fraction)

Added in API level 11

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.

public void setInterpolator (TimeInterpolator interpolator)

Added in API level 11

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.

public abstract void setValue (Object value)

Added in API level 11

Sets the value for this Keyframe.

Parameters
value Object: value for this Keyframe.