Android-based animationdrawable

Animationdrawable is a simple form of Android animation, which can be used to implement frame animation.

1. Define the friend. xml file under Res/drawable:

<?xml version="1.0" encoding="utf-8"?><animation-list android:oneshot="false"xmlns:android="http://schemas.android.com/apk/res/android"><item android:duration="400" android:drawable="@drawable/friend_light" /><item android:duration="400" android:drawable="@drawable/friend" /></animation-list> 

Each item is a frame, Android: Duration = "400" indicates that each frame lasts for 400 ms, and Android: drawable indicates the image to be displayed for each frame.

2. load and execute animations in Java code:

① Loading an animation

Button friend = (Button)findViewById(R.id.friend_btn);friend.setBackgroundResource(R.drawable.friend_anim);AnimationDrawable friend_anim= (AnimationDrawable) friend.getBackground();

② Execute the animation

friend_anim.start();

③ Stop the animation

friend_anim.stop();

3. Note:

By default, animation is executed in oncreate. start (); is invalid, because in oncreate (), animationdrawable is not completely bound to imageview. To start the animation in oncreate (), you can only see the first image.

Solution:

① Call getviewtreeobserver (). addonpredrawlistener () of View ()

friend.getViewTreeObserver().addOnPreDrawListener(new OnPreDrawListener(){@Overridepublic boolean onPreDraw() {// TODO Auto-generated method stubfriend_anim.start();return true;}});

② Use Handler

public void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.main);    friend = (Button)findViewById(R.id.friend_btn);    handler.postDelayed(new Runnable() {        public void run() {        friend.setBackgroundResource(R.drawable.friend_anim);        friend_anim = (AnimationDrawable) friend.getBackground();        friend_anim.start();        }    }, 50);}