Android实现可播放GIF动画的ImageView

<?xml version="1.0" encoding="utf-8"?> 
<resources> 
 <declare-styleable name="GifImageView"> 
  <attr name="auto_play" format="boolean"></attr> 
 </declare-styleable> 
</resources>

 private Movie mMovie;//播放动画需要用到的，系统类
 private int mImageWidth;//动画的imageview的宽度
 private int mImageHeight;//动画imageview的高度
 private long mMovieStart = 0;// 播放开始
 private boolean isAutoPlay;//是否自动播放
 private Bitmap mStartPlay;//开始按钮
 private boolean isPlaying=false;//记录是否正在播放
 private float mScale;//图片的缩放比
 private int mMeasuredGifWidth;//缩放后图片宽
 private int mMeasuredGifHeight;//缩放后图片高
 ...

 private void init(Context context, AttributeSet attrs) {
 TypedArray attributes = context.obtainStyledAttributes(attrs,R.styleable.GifImageView);
 // 通过反射拿布局中src的资源id,所以gif文件需要放在布局的src中
 int resourceId = getResourceId(attributes, context, attrs);
 if (resourceId != 0) {
  // 说明是gif动画
  // 1.将resourcesId变成流
  // 2.用Move来decode解析流
  // 3.获得bitmap的长宽
  InputStream is = getResources().openRawResource(resourceId);
  mMovie = Movie.decodeStream(is);
  if (mMovie != null) {
  Bitmap bitmap = BitmapFactory.decodeStream(is);
  mImageWidth = bitmap.getWidth();
  mImageHeight = bitmap.getHeight();
  // 用完释放
  bitmap.recycle();
  // 获得是否允许自动播放，如果不允许自动播放，则初始化播放按钮
  isAutoPlay = attributes.getBoolean(R.styleable.GifImageView_auto_play, false);
  if (!isAutoPlay) {
   mStartPlay = BitmapFactory.decodeResource(getResources(),R.drawable.start_play);
   setOnClickListener(this);
  }  
  }
 }
 //回收资源
 attributes.recycle();
 }

 /**
 * 通过反射拿布局中src的资源id
 * 
 * @param attrs
 * @param context
 * @param attributes
 */
 private int getResourceId(TypedArray attributes, Context context, AttributeSet attrs) {
 try {
  Field filed = TypedArray.class.getDeclaredField("mValue");
  filed.setAccessible(true);
  TypedValue typeValue = (TypedValue) filed.get(attributes);
  return typeValue.resourceId;
 } catch (Exception e) {
  e.printStackTrace();
 }
 }
 return 0;
}

 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
 super.onMeasure(widthMeasureSpec, heightMeasureSpec);
 if (mMovie != null) {
  /*
   * Calculate horizontal scaling
   */
  float scaleW = 1f;
  int measureModeWidth = MeasureSpec.getMode(widthMeasureSpec);
  if (measureModeWidth != MeasureSpec.UNSPECIFIED) {
   int maximumWidth = MeasureSpec.getSize(widthMeasureSpec);
   scaleW = (float) mImageWidth / (float) maximumWidth;
  }
  /*
   * calculate vertical scaling
   */
  float scaleH = 1f;
  int measureModeHeight = MeasureSpec.getMode(heightMeasureSpec);
  if (measureModeHeight != MeasureSpec.UNSPECIFIED) {
   int maximumHeight = MeasureSpec.getSize(heightMeasureSpec);
   scaleH = (float) mImageHeight / (float) maximumHeight;
  }
  /*
   * calculate overall scale
   */
  mScale = 1f / Math.max(scaleH, scaleW);
  mMeasuredGifWidth = (int) (mImageWidth * mScale);
  mMeasuredGifHeight = (int) (mImageHeight * mScale);
  setMeasuredDimension(mMeasuredGifWidth, mMeasuredGifHeight);
 }
 }

 @Override
 protected void onDraw(Canvas canvas) {
 if (mMovie == null) {
  // mMovie等于null，说明是张普通的图片，则直接调用父类的onDraw()方法
  super.onDraw(canvas);
 } else {
  // mMovie不等于null，说明是张GIF图片
  if (isAutoPlay) {
  // 如果允许自动播放，就播放
  playMovie(canvas);
  invalidate();
  } else {
  // 不允许自动播放的话
  // 1.判断是否正在播放
  // 2.获得第一帧的图像
  // 3.然后添加播放按钮
  if (isPlaying) {
   // 如果正在播放就playmoive继续播放
   if (playMovie(canvas)) {
   isPlaying = false;
   }
   invalidate();
  } else {
   // 第一帧
   mMovie.setTime(0);
   canvas.save(Canvas.MATRIX_SAVE_FLAG);
   canvas.scale(mScale, mScale);
   mMovie.draw(canvas, 0, 0);// 画
   canvas.restore();
   // 绘制开始按钮
   int offsetW = (mMeasuredGifWidth - mStartPlay.getWidth()) / 2;
   int offsetH = (mMeasuredGifHeight - mStartPlay.getHeight()) / 2;
   canvas.drawBitmap(mStartPlay, offsetW, offsetH, null);
  }
  }
 }
 }

 /**
 * 播放gif动画
 * 
 * @param canvas
 */
 private boolean playMovie(Canvas canvas) {
 // 1.获取播放的时间
 // 2.如果开始start=0，则认为是开始
 // 3.记录播放的时间
 // 4.设置进度
 // 5.画动画
 // 6.如果时间大于了播放的时间，则证明结束
 long now = SystemClock.uptimeMillis();
 if (mMovieStart == 0) {
  mMovieStart = now;
 }
 int duration = mMovie.duration();
 if (duration == 0) {
  duration = 1000;
 }
 //记录gif播放了多少时间
 int relTime = (int) ((now - mMovieStart) % duration);
 mMovie.setTime(relTime);// 设置时间
 canvas.save(Canvas.MATRIX_SAVE_FLAG);
 canvas.scale(mScale, mScale);
 mMovie.draw(canvas, 0, 0);// 画
 canvas.restore();
 if ((now - mMovieStart) >= duration) {
  // 结束
  mMovieStart = 0;
  return true;
 }
 return false;
 }

 @Override
 public void onClick(View v) {
 if(v.getId()==getId()){
  isPlaying=true;
  invalidate();
 }
 }

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:tools="http://schemas.android.com/tools"
 xmlns:attr="http://schemas.android.com/apk/res/com.hx.gifimageview"
 android:id="@+id/container"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical" >

 <com.hx.gifimageview.GifImageView
  android:layout_width="150dip"
  android:layout_height="150dip"
  android:layout_margin="10dp"
  android:src="@drawable/shulan"
  attr:auto_play="false" />

 <com.hx.gifimageview.GifImageView
  android:layout_width="150dip"
  android:layout_height="150dip"
  android:layout_margin="10dp"
  android:src="@drawable/shulan"
  attr:auto_play="true" />

 <com.hx.gifimageview.GifImageView
  android:layout_width="150dip"
  android:layout_height="150dip"
  android:layout_margin="10dp"
  android:src="@drawable/jingtai"
  attr:auto_play="true" />
</LinearLayout>