Android Application Resources-Animation Resources (III)

Plug-in

The plug-in is an editor defined in XML that can affect the frequency of animation changes. It will affect the acceleration, deceleration, replay, rebound, and other effects of existing animations.

Use the android: interpolator attribute to apply the plug-in to an animation element. Its value is a reference of a plug-in resource.

In Android, all available plug-ins are subclasses of the Interpolator class. For each plug-in makeup class, Android contains a public resource that can be referenced to apply this plug-in to the android: interpolator attribute used by animation. The following table specifies the resources available for each plug-in.

Plug-in
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
 

 

You can set the android: interpolator attribute as follows:

<Setandroid: interpolator = "@ android: anim/accelerate_interpolator">
...
</Set>

 

Custom plug-ins

If you are not satisfied with the plug-in Plug-In provided by the platform (the plug-in Plug-in listed in the above table), you can also edit the attribute method to create a custom plug-in resource. For example, you can adjust the acceleration frequency of the AnticipateInterpolator plug-in, or adjust the cycle quantity of the CycleInterpolator plug-in. To achieve this goal, you need to create your own plug-in resource in an XML file.

File location ):

Res/anim/filename. xml. The file name is used as the resource ID.

Compiled resource type (compiled resource datatype)

Resource pointing to the corresponding plug-in object

Resource reference ):

In XML: @ [package:] anim/filename

SYNTAX (SYNTAX ):

<? Xml version = "1.0" encoding = "UTF-8"?>
<InterpolatorNamexmlns: android = "http://schemas.android.com/apk/res/android"
Android: attribute_name = "value"
/>

If no attributes are applied, the customized plug-in will have the same functions as the plug-in provided by the platform.

Element (ELEMENTS ):

Note that the implementation of each plug-in is defined in XML and starts with a lowercase letter.

<AccelerateDecelerateInterpolator>

Reduces the frequency of changes at the animation start and end, but accelerates at the center of the animation.

No attribute

<AccelerateInterpolator>

Reduces the frequency of changes when the animation starts and starts acceleration.

ATTRIBUTES (ATTRIBUTES ):

Android: factor

Floating point value, specifying the acceleration frequency (1 by default)

<AnticipateInterpolator>

When the animation starts, it first changes backward and then forward (rubber band effect ).

ATTRIBUTES (ATTRIBUTES ):

Android: tension

Floating point value, specifying the number of tension (2 by default)

<AnticipateOvershootInterpolator>

When the animation is started, it first goes backward, then goes forward, and flies over the target value, and then ends stably.

ATTRIBUTES (ATTRIBUTES ):

Android: tension

Floating point value, specifying the number of tension (2 by default)

Android: extraTension

Floating point value, specifying a multiple of tension (default value: 1.5)

<BounceInterpolator>

The bounce effect at the end of the animation.

No attribute

<CycleInterpolator>

Repeat the animation with the specified number of loops. The variation frequency is in the sine pattern.

ATTRIBUTES (ATTRIBUTES ):

Android: cycles

An integer that specifies the number of cycles (1 by default ).

<DecelerateInterpolator>

When the animation starts, it quickly jumps out and then slows down.

ATTRIBUTES (ATTRIBUTES ):

Android: factor

Floating point value, specifying the deceleration ratio (default value: 1)

<LinearInterpolator>

The animation change frequency is fixed.

No attribute.

<OvershootInterpolator>

Throw forward, fly over the terminal, and return back.

ATTRIBUTES (ATTRIBUTES ):

Android: tension

Floating point value, set the number of tension (2 by default)

Example:

The XML file is saved in res/anim/my_overshoot_interpolator.xml:

<? Xml version = "1.0" encoding = "UTF-8"?>
<OvershootInterpolatorxmlns: android = "http://schemas.android.com/apk/res/android"
Android: tension= "7.0"
/>

The following is the plug-in used by the animation XML:

<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: Required Tx = "50%"
Android: Ty = "50%"
Android: duration = "700"/>

Frame Animation

An animation is defined in XML. It plays an image in sequence like a movie.

File location ):

Res/drawable/filename. xml

The file name is used as the resource ID.

Compiled resource type (compiled resource datatype ):

The resource points to an AnimationDrawable object.

RESOURCE REFERENCE)

In Java code: R. drawable. filename

In XML: @ [package:] drawable. filename

SYNTAX (SYNTAX ):

<? Xml version = "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>

 

Element (ELEMENTS ):

<Animation-list>

Required. It must be a root element. It must contain one or more <item> elements.

ATTRIBUTES (ATTRIBUTES ):

Android: oneshot

Boolean value. If you only want to run the animation once, set it to "true". Otherwise, set it to "false" to play the animation cyclically.

<Item>

An animation frame must be a child element of the <animation-list> element.

ATTRIBUTES (ATTRIBUTES ):

Android: drawable

Specifies the plotting resource used for the current animation.

Android: duration

Integer, in milliseconds, shows the animation duration.

Example:

The XML file is saved in res/anim/rocket. xml:

<? Xml version = "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 application code sets this animation as the background of a View object and then plays the animation:

ImageView rocketImage = (ImageView) findViewById (R. id. rocket_image );
RocketImage. setBackgroundResource (R. drawable. rocket_thrust );

RocketAnimation = (AnimationDrawable) rocketImage. getBackground ();
RocketAnimation. start ();

 

From FireOfStar's column