An animation resource can define one of two types of animations:
Animation.AnimationDrawable.An animation defined in XML that performs transitions such as rotating, fading, moving, and stretching on a graphic.
res/anim/filename.xmlAnimation.R.anim.filename@[package:]anim/filename
<?xml version="1.0" encoding="utf-8"?> <set xmlns: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:fromX="float" android:toX="float" android:fromY="float" android:toY="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 (even nested <set> elements).
res/anim/hyperspace_jump.xml:
<set xmlns: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>
This application code will apply the animation to an ImageView and
start the animation:
ImageView image = (ImageView) findViewById(R.id.image); Animation hyperspaceJump = AnimationUtils.loadAnimation(this, R.anim.hyperspace_jump); image.startAnimation(hyperspaceJump);
An interpolator is an animation modifier defined in XML that affects the rate of change in an animation. This allows your existing animation effects to 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 in order to apply the interpolator to an animation
using the the android:interpolator attribute.
The following table specifies the resource to use for each interpolator:
| Interpolator class | Resource ID |
|---|---|
AccelerateDecelerateInterpolator |
@android:anim/accelerate_decelerate_interpolator |
AccelerateInterpolator |
@android:anim/accelerate_interpolator |
AnticipateInterpolator |
@android:anim/anticipate_interpolator |
AnticipateOvershootInterpolator |
@android:anim/anticipate_overshoot_interpolator |
BounceInterpolator |
@android:anim/bounce_interpolator |
CycleInterpolator |
@android:anim/cycle_interpolator |
DecelerateInterpolator |
@android:anim/decelerate_interpolator |
LinearInterpolator |
@android:anim/linear_interpolator |
OvershootInterpolator |
@android:anim/overshoot_interpolator |
Here's how you can apply one of these with the android:interpolator attribute:
<set android:interpolator="@android:anim/accelerate_interpolator">
...
</set>
If you're not satisfied with the interpolators provided by the platform (listed in the
table above), 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. In order to do so, you need to
create your own interpolator resource in an XML file.
res/anim/filename.xml@[package:]anim/filename
<?xml version="1.0" encoding="utf-8"?>
<InterpolatorName xmlns:android="http://schemas.android.com/apk/res/android"
android:attribute_name="value"
/>
If you don't apply any attributes, then your interpolator will function exactly the same as those provided by the platform (listed in the table above).
Interpolator implementation, when
defined in XML, begins its name in lowercase.
XML file saved at res/anim/my_overshoot_interpolator.xml:
<?xml version="1.0" encoding="utf-8"?>
<overshootInterpolator xmlns:android="http://schemas.android.com/apk/res/android"
android:tension="7.0"
/>
This animation XML will apply the interpolator:
<scale xmlns: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" />
An animation defined in XML that shows a sequence of images in order (like a film).
res/drawable/filename.xmlAnimationDrawable.R.drawable.filename@[package:]drawable.filename
<?xml version="1.0" encoding="utf-8"?> <animation-list xmlns: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>
res/anim/rocket.xml:
<?xml version="1.0" encoding="utf-8"?>
<animation-list xmlns:android="http://schemas.android.com/apk/res/android"
android:oneshot="false">
<item android:drawable="@drawable/rocket_thrust1" android:duration="200" />
<item android:drawable="@drawable/rocket_thrust2" android:duration="200" />
<item android:drawable="@drawable/rocket_thrust3" android:duration="200" />
</animation-list>
ImageView rocketImage = (ImageView) findViewById(R.id.rocket_image); rocketImage.setBackgroundResource(R.drawable.rocket_thrust); rocketAnimation = (AnimationDrawable) rocketImage.getBackground(); rocketAnimation.start();