Android播放GIF动画

Android支持GIF动画，但是如果利用ImageView标签直接写在布局文件中：

<ImageView android:id="@+id/gifpicture"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:src="@drawable/animation"    />

<ImageView android:id="@+id/gifpicture" 
android:layout_width="fill_parent" 
android:layout_height="wrap_content" 
android:src="@drawable/animation"    />

程序只能加载GIF动画的第一帧。效果如下：


如果想要正常播放GIF动画，需要借助Movie实现。写了一个简单示例，程序目录结构如下：


animation.gif是需要播放的GIF动画。
MainActivity实现了加载GIF动画的功能。

public class MainActivity extends Activity {

    private Movie mMovie;
    private long mMovieStart;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
       setContentView(new CustomGifView(this));
          }
    class CustomGifView extends View {
        public CustomGifView(Context context) {
            super(context);
            mMovie = Movie.decodeStream(getResources().openRawResource(
                    R.drawable.animation));
        }

        public void onDraw(Canvas canvas) {
            long now = android.os.SystemClock.uptimeMillis();

            if (mMovieStart == 0) { // first time
                mMovieStart = now;
            }
            if (mMovie != null) {

                int dur = mMovie.duration();
                if (dur == 0) {
                    dur = 1000;
                }
                int relTime = (int) ((now – mMovieStart) % dur);
                mMovie.setTime(relTime);
                mMovie.draw(canvas, 0, 0);
                invalidate();
            }
        }
    }
}

public class MainActivity extends Activity { 
    
    private Movie mMovie; 
    private long mMovieStart;
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
       setContentView(new CustomGifView(this)); 
          }
    class CustomGifView extends View {
        public CustomGifView(Context context) { 
            super(context); 
            mMovie = Movie.decodeStream(getResources().openRawResource( 
                    R.drawable.animation));
        } 
        
        public void onDraw(Canvas canvas) {
            long now = android.os.SystemClock.uptimeMillis(); 
            
            if (mMovieStart == 0) { // first time 
                mMovieStart = now; 
            } 
            if (mMovie != null) { 
                
                int dur = mMovie.duration(); 
                if (dur == 0) { 
                    dur = 1000; 
                } 
                int relTime = (int) ((now – mMovieStart) % dur);                
                mMovie.setTime(relTime); 
                mMovie.draw(canvas, 0, 0); 
                invalidate(); 
            } 
        }
    }
}

内部类CustomGifView 利用Movie播放GIF动画。解释一下：

mMovie = Movie.decodeStream(getResources().openRawResource(R.drawable.animation));

mMovie = Movie.decodeStream(getResources().openRawResource(R.drawable.animation));

将GIF动画以文件流的形式转换成Movie。

public void onDraw(Canvas canvas) {
        long now = android.os.SystemClock.uptimeMillis();

        if (mMovieStart == 0) { // first time
            mMovieStart = now;
        }
        if (mMovie != null) {

            int dur = mMovie.duration();
            if (dur == 0) {
                dur = 1000;
            }
            int relTime = (int) ((now – mMovieStart) % dur);
            mMovie.setTime(relTime);
            mMovie.draw(canvas, 0, 0);
            invalidate();
        }
    }

public void onDraw(Canvas canvas) {
        long now = android.os.SystemClock.uptimeMillis(); 
        
        if (mMovieStart == 0) { // first time 
            mMovieStart = now; 
        } 
        if (mMovie != null) { 
            
            int dur = mMovie.duration(); 
            if (dur == 0) { 
                dur = 1000; 
            } 
            int relTime = (int) ((now – mMovieStart) % dur);                
            mMovie.setTime(relTime); 
            mMovie.draw(canvas, 0, 0); 
            invalidate(); 
        } 
    }

   invalidate();作用是刷新当前View，这样onDraw方法重复执行，Movie就能画出GIF动画的每一帧。到此，GIF动画就能正常播放了。



源代码见：http://bigcateasymorse.googlecode.com/svn/trunk/android_gif_demo/