Animation resources

An animation resource can define one of two types of animations:

Property animation

Creates an animation by modifying an object's property values over a set period with an Animator .

View animation

There are two types of animations that you can do with the view animation framework:

• Tween animation: creates an animation by performing a series of transformations on a single image with an Animation .
• Frame animation: creates an animation by showing a sequence of images in order with an AnimationDrawable .

Property animation

An animation defined in XML that modifies properties of the target object, such as background color or alpha value, over a set amount of time.

file location:

res/animator/filename.xml
The filename is used as the resource ID.

compiled resource datatype:

Resource pointer to a ValueAnimator , ObjectAnimator , or AnimatorSet

resource reference:

In Java-based or Kotlin code: R.animator.filename
In XML: @[package:]animator/filename

syntax:

<set
android:ordering=["together"|"sequentially"]>
<objectAnimator
android:propertyName="string"
android:duration="int"
android:valueFrom="float|int|color"
android:valueTo="float|int|color"
android:startOffset="int"
android:repeatCount="int"
android:repeatMode=["restart"|"reverse"]
android:valueType=["intType"|"floatType"]/>
<animator
android:duration="int"
android:valueFrom="float|int|color"
android:valueTo="float|int|color"
android:startOffset="int"
android:repeatCount="int"
android:repeatMode=["restart"|"reverse"]
android:valueType=["intType"|"floatType"]/>
<set>
...
</set>
</set>

The file must have a single root element: either <set>, <objectAnimator>, or <valueAnimator>. You can group animation elements together inside the <set> element, including other <set> elements.

elements:

<set>

A container that holds other animation elements (<objectAnimator>, <valueAnimator>, or other <set> elements). Represents an AnimatorSet .

You can specify nested <set> tags to further group animations. Each <set> can define its own ordering attribute.

Attributes:

android:ordering

Keyword. Specifies the play ordering of animations in this set.

Value	Description
sequentially	Play animations in this set sequentially.
together (default)	Play animations in this set at the same time.

<objectAnimator>

Animates a specific property of an object over a specific amount of time. Represents an ObjectAnimator .

Attributes:

android:propertyName

String. Required. The object's property to animate, referenced by its name. For example, you can specify "alpha" or "backgroundColor" for a View object. The objectAnimator element doesn't expose a target attribute, however, so you can't set the object to animate in the XML declaration. You have to inflate your animation XML resource by calling loadAnimator() , and call setTarget() to set the target object that contains this property.

android:valueTo

float, int, or color. Required. The value where the animated property ends. Colors are represented as six-digit hexadecimal numbers, such as #333333.

android:valueFrom

float, int, or color. The value where the animated property starts. If not specified, the animation starts at the value obtained by the property's get method. Colors are represented as six-digit hexadecimal numbers, such as #333333.

android:duration

int. The time in milliseconds of the animation. 300 milliseconds is the default.

android:startOffset

int. The amount of milliseconds the animation delays after start() is called.

android:repeatCount

int. How many times to repeat an animation. Set to "-1" to infinitely repeat or to a positive integer. For example, a value of "1" means that the animation is repeated once after the initial run of the animation, so the animation plays a total of two times. The default value is "0", which means no repetition.

android:repeatMode

int. How an animation behaves when it reaches the end of the animation. android:repeatCount must be set to a positive integer or "-1" for this attribute to have an effect. Set to "reverse" to have the animation reverse direction with each iteration or "restart" to have the animation loop from the beginning each time.

android:valueType

Keyword. Don't specify this attribute if the value is a color. The animation framework automatically handles color values.

Value	Description
intType	Specifies that the animated values are integers.
floatType (default)	Specifies that the animated values are floats.

<animator>

Performs an animation over a specified amount of time. Represents a ValueAnimator .

Attributes:

android:valueTo

float, int, or color. Required. The value where the animation ends. Colors are represented as six-digit hexadecimal numbers, such as #333333.

android:valueFrom

float, int, or color. Required. The value where the animation starts. Colors are represented as six-digit hexadecimal numbers, such as #333333.

android:duration

int. The time in milliseconds of the animation. 300ms is the default.

android:startOffset

int. The amount of milliseconds the animation delays after start() is called.

android:repeatCount

int. How many times to repeat an animation. Set to "-1" to infinitely repeat or to a positive integer. For example, a value of "1" means that the animation is repeated once after the initial run of the animation, so the animation plays a total of two times. The default value is "0", which means no repetition.

android:repeatMode

int. How an animation behaves when it reaches the end of the animation. android:repeatCount must be set to a positive integer or "-1" for this attribute to have an effect. Set to "reverse" to have the animation reverse direction with each iteration or "restart" to have the animation loop from the beginning each time.

android:valueType

Keyword. Don't specify this attribute if the value is a color. The animation framework automatically handles color values.

Value	Description
intType	Specifies that the animated values are integers.
floatType (default)	Specifies that the animated values are floats.

example:

XML file saved at res/animator/property_animator.xml:

<setandroid:ordering="sequentially">
<set>
<objectAnimator
android:propertyName="x"
android:duration="500"
android:valueTo="400"
android:valueType="intType"/>
<objectAnimator
android:propertyName="y"
android:duration="500"
android:valueTo="300"
android:valueType="intType"/>
</set>
<objectAnimator
android:propertyName="alpha"
android:duration="500"
android:valueTo="1f"/>
</set>

To run this animation, inflate the XML resources in your code to an AnimatorSet object, and then set the target objects for all the animations before starting the animation set. Calling setTarget() sets a single target object for all children of the AnimatorSet as a convenience. The following code shows how to do this:

Kotlin

valset:AnimatorSet=AnimatorInflater.loadAnimator(myContext,R.animator.property_animator)
.apply{
setTarget(myObject)
start()
}

Java

AnimatorSetset=(AnimatorSet)AnimatorInflater.loadAnimator(myContext,
R.animator.property_animator);
set.setTarget(myObject);
set.start();

see also:

• Property Animation Overview
• API demos for examples of how to use the property animation system

View animation

The view animation framework supports both tween and frame-by-frame animations, which are both declared in XML. The following sections describe how to use both methods.

Tween animation

An animation defined in XML that performs transitions on a graphic such as rotating, fading, moving, and stretching.

file location:

res/anim/filename.xml
The filename is used as the resource ID.

compiled resource datatype:

Resource pointer to an Animation

resource reference:

In Java: R.anim.filename
In XML: @[package:]anim/filename

syntax:

<?xmlversion="1.0"encoding="utf-8"?>
<setxmlns:android="http://schemas.android.com/apk/res/android"
android:interpolator="@[package:]anim/interpolator_resource"
android:shareInterpolator=["true"|"false"]>
<alpha
android:fromAlpha="float"
android:toAlpha="float"/>
<scale
android:fromXScale="float"
android:toXScale="float"
android:fromYScale="float"
android:toYScale="float"
android:pivotX="float"
android:pivotY="float"/>
<translate
android:fromXDelta="float"
android:toXDelta="float"
android:fromYDelta="float"
android:toYDelta="float"/>
<rotate
android:fromDegrees="float"
android:toDegrees="float"
android:pivotX="float"
android:pivotY="float"/>
<set>
...
</set>
</set>

The file must have a single root element: either an <alpha>, <scale>, <translate>, <rotate>, or <set> element that holds a group (or groups) of other animation elements (including nested <set> elements).

elements:

<set>

A container that holds other animation elements (<alpha>, <scale>, <translate>, <rotate>) or other <set> elements. Represents an AnimationSet .

Attributes:

android:interpolator

Interpolator resource. An Interpolator to apply on the animation. The value must be a reference to a resource that specifies an interpolator, not an interpolator class name. There are default interpolator resources available from the platform or you can create your own interpolator resource. See the following discussion for more information about interpolators.

android:shareInterpolator

Boolean. "true" if you want to share the same interpolator among all child elements.

<alpha>

A fade-in or fade-out animation. Represents an AlphaAnimation .

Attributes:

android:fromAlpha

Float. Starting opacity offset, where 0.0 is transparent and 1.0 is opaque.

android:toAlpha

Float. Ending opacity offset, where 0.0 is transparent and 1.0 is opaque.

For more attributes supported by <alpha>, see the class reference for Animation , whose XML attributes are inherited by this element.

<scale>

A resizing animation. You can specify the center point of the image from which it grows outward or inward by specifying pivotX and pivotY. For example, if these values are 0,0 (the top-left corner), all growth is down and to the right. Represents a ScaleAnimation .

Attributes:

android:fromXScale

Float. Starting X size offset, where 1.0 is no change.

android:toXScale

Float. Ending X size offset, where 1.0 is no change.

android:fromYScale

Float. Starting Y size offset, where 1.0 is no change.

android:toYScale

Float. Ending Y size offset, where 1.0 is no change.

android:pivotX

Float. The X coordinate to remain fixed when the object is scaled.

android:pivotY

Float. The Y coordinate to remain fixed when the object is scaled.

For more attributes supported by <scale>, see the class reference for Animation , whose XML attributes are inherited by this element.

<translate>

A vertical and/or horizontal motion. Represents a TranslateAnimation . Supports the following attributes in any of these three formats:

• Values from -100 to 100 ending with "%", indicating a percentage relative to itself.
• Values from -100 to 100 ending in "%p", indicating a percentage relative to its parent.
• A float value with no suffix, indicating an absolute value.

Attributes:

android:fromXDelta

Float or percentage. Starting X offset. Expressed either in pixels relative to the normal position, such as "5"; in percentage relative to the element width, such as "5%"; or in percentage relative to the parent width, such as "5%p".

android:toXDelta

Float or percentage. Ending X offset. Expressed either in pixels relative to the normal position, such as "5"; in percentage relative to the element width, such as "5%"; or in percentage relative to the parent width, such as "5%p".

android:fromYDelta

Float or percentage. Starting Y offset. Expressed either in pixels relative to the normal position, such as "5"; in percentage relative to the element height, such as "5%"; or in percentage relative to the parent height, such as "5%p".

android:toYDelta

Float or percentage. Ending Y offset. Expressed either in pixels relative to the normal position, such as "5"; in percentage relative to the element height, such as "5%"; or in percentage relative to the parent height, such as "5%p".

For more attributes supported by <translate>, see the class reference for Animation , whose XML attributes are inherited by this element.

<rotate>

A rotation animation. Represents a RotateAnimation .

Attributes:

android:fromDegrees

Float. Starting angular position, in degrees.

android:toDegrees

Float. Ending angular position, in degrees.

android:pivotX

Float or percentage. The X coordinate of the center of rotation. Expressed either in pixels relative to the object's left edge, such as "5"; in percentage relative to the object's left edge, such as "5%"; or in percentage relative to the parent container's left edge, such as "5%p".

android:pivotY

Float or percentage. The Y coordinate of the center of rotation. Expressed either in pixels relative to the object's top edge, such as "5"; in percentage relative to the object's top edge, such as "5%"; or in percentage relative to the parent container's top edge, such as "5%p".

For more attributes supported by <rotate>, see the class reference for Animation , whose XML attributes are inherited by this element.

example:

XML file saved at res/anim/hyperspace_jump.xml:

<setxmlns:android="http://schemas.android.com/apk/res/android"
android:shareInterpolator="false">
<scale
android:interpolator="@android:anim/accelerate_decelerate_interpolator"
android:fromXScale="1.0"
android:toXScale="1.4"
android:fromYScale="1.0"
android:toYScale="0.6"
android:pivotX="50%"
android:pivotY="50%"
android:fillAfter="false"
android:duration="700"/>
<set
android:interpolator="@android:anim/accelerate_interpolator"
android:startOffset="700">
<scale
android:fromXScale="1.4"
android:toXScale="0.0"
android:fromYScale="0.6"
android:toYScale="0.0"
android:pivotX="50%"
android:pivotY="50%"
android:duration="400"/>
<rotate
android:fromDegrees="0"
android:toDegrees="-45"
android:toYScale="0.0"
android:pivotX="50%"
android:pivotY="50%"
android:duration="400"/>
</set>
</set>

The following application code applies the animation to an ImageView and starts the animation:

Kotlin

valimage:ImageView=findViewById(R.id.image)
valhyperspaceJump:Animation=AnimationUtils.loadAnimation (this,R.anim.hyperspace_jump)
image.startAnimation (hyperspaceJump)

Java

ImageViewimage=(ImageView)findViewById(R.id.image);
AnimationhyperspaceJump=AnimationUtils.loadAnimation (this,R.anim.hyperspace_jump);
image.startAnimation (hyperspaceJump);

see also:

• View Animation

Interpolators

An interpolator is an animation modifier defined in XML that affects the rate of change in an animation. This lets your existing animation effects be accelerated, decelerated, repeated, bounced, etc.

An interpolator is applied to an animation element with the android:interpolator attribute, the value of which is a reference to an interpolator resource.

All interpolators available in Android are subclasses of the Interpolator class. For each interpolator class, Android includes a public resource you can reference to apply the interpolator to an animation using the android:interpolator attribute. The following table specifies the resource to use for each interpolator:

Here's how you can apply one of these with the android:interpolator attribute:

<setandroid:interpolator="@android:anim/accelerate_interpolator">
...
</set>

Custom interpolators

If you're not satisfied with the interpolators provided by the platform, you can create a custom interpolator resource with modified attributes. For example, you can adjust the rate of acceleration for the AnticipateInterpolator or adjust the number of cycles for the CycleInterpolator . To do so, you create your own interpolator resource in an XML file.

file location:

res/anim/filename.xml
The filename is used as the resource ID.

compiled resource datatype:

Resource pointer to the corresponding interpolator object

resource reference:

In XML: @[package:]anim/filename

syntax:

<?xmlversion="1.0"encoding="utf-8"?>
<InterpolatorNamexmlns:android="http://schemas.android.com/apk/res/android"
android:attribute_name="value"
/>

If you don't apply any attributes, then your interpolator functions exactly the same as those provided by the platform, listed in the preceding table.

elements:

Notice that each Interpolator implementation, when defined in XML, has a name that begins with a lowercase letter.

<accelerateDecelerateInterpolator>

The rate of change starts and ends slowly but accelerates through the middle.

No attributes.

<accelerateInterpolator>

The rate of change starts slowly, then accelerates.

Attributes:

android:factor

Float. The acceleration rate. The default is 1.

<anticipateInterpolator>

The change starts backward, then flings forward.

Attributes:

android:tension

Float. The amount of tension to apply. The default is 2.

<anticipateOvershootInterpolator>

The change starts backward, then flings forward and overshoots the target value, then settles at the final value.

Attributes:

android:tension

Float. The amount of tension to apply. The default is 2.

android:extraTension

Float. The amount by which to multiply the tension. The default is 1.5.

<bounceInterpolator>

The change bounces at the end.

No attributes

<cycleInterpolator>

Repeats the animation for a specified number of cycles. The rate of change follows a sinusoidal pattern.

Attributes:

android:cycles

Integer. The number of cycles. The default is 1.

<decelerateInterpolator>

The rate of change starts out quickly, then decelerates.

Attributes:

android:factor

Float. The deceleration rate. The default is 1.

<linearInterpolator>

The rate of change is constant.

No attributes.

<overshootInterpolator>

The change flings forward and overshoots the last value, then comes back.

Attributes:

android:tension

Float. The amount of tension to apply. The default is 2.

example:

XML file saved at res/anim/my_overshoot_interpolator.xml:

<?xmlversion="1.0"encoding="utf-8"?>
<overshootInterpolatorxmlns:android="http://schemas.android.com/apk/res/android"
android:tension="7.0"
/>

This animation XML applies the interpolator:

<scalexmlns:android="http://schemas.android.com/apk/res/android"
android:interpolator="@anim/my_overshoot_interpolator"
android:fromXScale="1.0"
android:toXScale="3.0"
android:fromYScale="1.0"
android:toYScale="3.0"
android:pivotX="50%"
android:pivotY="50%"
android:duration="700"/>

Frame animation

An animation defined in XML that shows a sequence of images in order, like a film.

file location:

res/drawable/filename.xml
The filename is used as the resource ID.

compiled resource datatype:

Resource pointer to an AnimationDrawable

resource reference:

In Java: R.drawable.filename
In XML: @[package:]drawable.filename

syntax:

<?xmlversion="1.0"encoding="utf-8"?>
<animation-listxmlns:android="http://schemas.android.com/apk/res/android"
android:oneshot=["true"|"false"]>
<item
android:drawable="@[package:]drawable/drawable_resource_name"
android:duration="integer"/>
</animation-list>

elements:

<animation-list>

Required. This must be the root element. Contains one or more <item> elements.

Attributes:

android:oneshot

Boolean. "true" if you want to perform the animation once; "false" to loop the animation.

<item>

A single frame of animation. Must be a child of a <animation-list> element.

Attributes:

android:drawable

Drawable resource. The drawable to use for this frame.

android:duration

Integer. The duration to show this frame, in milliseconds.

example:

XML file saved at res/drawable/rocket_thrust.xml:

<?xmlversion="1.0"encoding="utf-8"?>
<animation-listxmlns:android="http://schemas.android.com/apk/res/android"
android:oneshot="false">
<itemandroid:drawable="@drawable/rocket_thrust1"android:duration="200"/>
<itemandroid:drawable="@drawable/rocket_thrust2"android:duration="200"/>
<itemandroid:drawable="@drawable/rocket_thrust3"android:duration="200"/>
</animation-list>

The following application code sets the animation as the background for a View, then play the animation:

Kotlin

valrocketImage:ImageView=findViewById(R.id.rocket_image)
rocketImage.setBackgroundResource (R.drawable.rocket_thrust)
valrocketAnimation=rocketImage.background 
if(rocketAnimationisAnimatable ){
rocketAnimation.start() 
}

Java

ImageViewrocketImage=(ImageView)findViewById(R.id.rocket_image);
rocketImage.setBackgroundResource (R.drawable.rocket_thrust);
rocketAnimation=rocketImage.getBackground() ;
if(rocketAnimationinstanceofAnimatable ){
((Animatable)rocketAnimation).start() ;
}

see also:

• View Animation