Android(安卓)之AnimationDrawable

AnimationDrawable是Android实现动画的一种简单的形式。如果需要简单的动画，例如屏幕锁。这里用一个Demo来简单讲解下。

首先最基本的，我们可以参见DOC上的说明，它的资料最正宗！

Class Overview

An object used to create frame-by-frame animations, defined by a series of Drawable objects, which can be used as a View object's background.

The simplest way to create a frame-by-frame animation is to define the animation in an XML file, placed in the res/drawable/ folder, and set it as the background to a View object. Then, call run() to start the animation.

An AnimationDrawable defined in XML consists of a single <animation-list> element, and a series of nested <item> tags. Each item defines a frame of the animation. See the example below.

spin_animation.xml file in res/drawable/ folder:

<!-- Animation frames are wheel0.png -- wheel5.png files inside the
res/drawable/ folder -->
<animation-list android:id="selected" android:oneshot="false">
  <item android:drawable="@drawable/wheel0" android:duration="50" />
  <item android:drawable="@drawable/wheel1" android:duration="50" />
  <item android:drawable="@drawable/wheel2" android:duration="50" />
  <item android:drawable="@drawable/wheel3" android:duration="50" />
  <item android:drawable="@drawable/wheel4" android:duration="50" />
  <item android:drawable="@drawable/wheel5" android:duration="50" />
</animation-list>

Here is the code to load and play this animation.

// Load the ImageView that will host the animation and
// set its background to our AnimationDrawable XML resource.
ImageView img = (ImageView)findViewById(R.id.spinning_wheel_image);
img.setBackgroundResource(R.drawable.spin_animation);

// Get the background, which has been compiled to an AnimationDrawable object.
AnimationDrawable frameAnimation = (AnimationDrawable) img.getBackground();

// Start the animation (looped playback by default).
frameAnimation.start()

以上的资料大家也可以在DOC中看的很明白。

一：新建一个工程AnimationDrawableDemo。
二：在res/drawable下面放入我们需要演示的图片。
lock_anim_00.png
lock_anim_02.png
lock_anim_04.png
lock_anim_06.png
lock_anim_08.png
lock_anim_10.png
lock_anim_12.png
lock_anim_14.png


新建一个Animation资源文件。文件如下：
<?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/lock_anim_00" android:duration="400" />    <item android:drawable="@drawable/lock_anim_02" android:duration="400" />    <item android:drawable="@drawable/lock_anim_04" android:duration="400" />    <item android:drawable="@drawable/lock_anim_06" android:duration="400" />    <item android:drawable="@drawable/lock_anim_08" android:duration="400" />    <item android:drawable="@drawable/lock_anim_10" android:duration="400" />    <item android:drawable="@drawable/lock_anim_12" android:duration="400" />    <item android:drawable="@drawable/lock_anim_14" android:duration="400" /></animation-list> 

三：在main.xml文件中导入一个ImageView控件。函数代码如下：
package com.rocky.studio.ch02.ex2;import android.app.Activity;import android.content.DialogInterface;import android.content.DialogInterface.OnClickListener;import android.graphics.drawable.AnimationDrawable;import android.os.Bundle;import android.os.Handler;import android.view.View;import android.widget.Button;import android.widget.ImageView;public class AnimationDrawableDemo extends Activity {private Button m_RunButton;private Button m_StopButton;private ImageView imgView;private AnimationDrawable mAnimation;private static final long START_DELAY = 1000;private Handler mHandler = new Handler();    private Runnable mRunnable = new Runnable() {        public void run() {            startAnimation(mAnimation);        }    };    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);                        m_RunButton=(Button)this.findViewById(R.id.Button01);        m_StopButton=(Button)this.findViewById(R.id.Button02);        m_RunButton.setOnClickListener( m_BtnRunClickListener);        m_StopButton.setOnClickListener(m_BtnStopClickListener);               imgView=(ImageView)this.findViewById(R.id.ImageView01);                imgView.setBackgroundResource(R.drawable.lock_anim);        mAnimation = (AnimationDrawable) imgView.getBackground();    }    @Overrideprotected void onPause() {// TODO Auto-generated method stubsuper.onPause();//stopAnimation(mAnimation);}@Overrideprotected void onResume() {// TODO Auto-generated method stubsuper.onResume();//mHandler.postDelayed(mRunnable, START_DELAY);}private View.OnClickListener m_BtnRunClickListener=new View.OnClickListener()    {public void onClick(View arg0) {// TODO Auto-generated method stubstartAnimation(mAnimation);}        };    private View.OnClickListener m_BtnStopClickListener=new View.OnClickListener()    {public void onClick(View arg0) {// TODO Auto-generated method stubstopAnimation(mAnimation);}    };    protected void startAnimation(final AnimationDrawable animation) {        if (animation != null && !animation.isRunning()) {            animation.run();        }    }       protected void stopAnimation(final AnimationDrawable animation) {        if (animation != null && animation.isRunning()) animation.stop();    }    } 


四：如果需要一打开就动画显示：//mHandler.postDelayed(mRunnable, START_DELAY);
这句话的意思是开启一个线程，开始执行操作。

五：这样就基本完成了操作。最好还是些个Demo来测试练练手。

Class Overview

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