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：
Xml代码





<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。
Java代码





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：
Java代码





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。
Java代码





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/