An animation resource can define one of two types of animations:
- Tween Animation
- Creates an animation by performing a series of transformations on a single image.
An
Animation
.
- Frame Animation
- Creates an animation by showing a sequence of images in order.
An
AnimationDrawable
.
Tween Animation
An animation defined in XML that performs transitions such as rotating,
fading, moving, and stretching on a graphic.
- file location:
res/anim/filename.xml
The filename will be 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:
-
<?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).
- 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 discussion below for more 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
Animation
class reference (of which, all XML attributes are
inherrited 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 (top-left corner), all growth will be 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
Animation
class reference (of which, all XML attributes are
inherrited by this element).
<translate>
- A vertical and/or horizontal motion. Supports the following attributes in any of
the following 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. Represents a
TranslateAnimation
.
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
Animation
class reference (of which, all XML attributes are
inherrited 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
Animation
class reference (of which, all XML attributes are
inherrited by this element).
- example:
-
XML file saved at
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);
- see also:
-
Interpolators
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:
Here's how you can apply one of these with the android:interpolator
attribute:
<set android:interpolator="@android:anim/accelerate_interpolator">
...
</set>
Custom interpolators
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.
- file location:
res/anim/filename.xml
The filename will be used as the resource ID.
- compiled resource datatype:
- Resource pointer to the corresponding interpolator object.
- resource reference:
-
In XML:
@[package:]anim/filename
- syntax:
-
<?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).
- elements:
- Notice that each
Interpolator
implementation, when
defined in XML, begins its name in lowercase.
<accelerateDecelerateInterpolator>
- The rate of change starts and ends slowly but accelerates through the
middle.
No attributes.
<accelerateInterpolator>
- The rate of change starts out slowly, then accelerates.
attributes:
android:factor
- Float. The acceleration rate (default is 1).
<anticipateInterpolator>
- The change starts backward then flings forward.
attributes:
android:tension
- Float. The amount of tension to apply (default is 2).
<anticipateOvershootInterpolator>
- The change starts backward, flings forward and overshoots the target value, then
settles at the final value.
attributes:
android:tension
- Float. The amount of tension to apply (default is 2).
android:extraTension
- Float. The amount by which to multiply the tension (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 (default is 1).
<decelerateInterpolator>
- The rate of change starts out quickly, then decelerates.
attributes:
android:factor
- Float. The deceleration rate (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 (default is 2).
- example:
-
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" />
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 will be 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:
-
<?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>
- 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/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>
- This application code will set the animation as the background for a View,
then play the animation:
-
ImageView rocketImage = (ImageView) findViewById(R.id.rocket_image);
rocketImage.setBackgroundResource
(R.drawable.rocket_thrust);
rocketAnimation = (AnimationDrawable) rocketImage.getBackground()
;
rocketAnimation.start()
;
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