@Override
public boolean onTouchEvent(MotionEvent event) {
  switch (event.getAction()) {
  case MotionEvent.ACTION_UP:
    flingView.onFling(0); // 手指抬起后，重置滑动距离offsetX = 0
    break;
  }
  return myGesture.onTouchEvent(event);
}

@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
  flingView.handleScroll(-1 * (int) distanceX);
  return true;
}

@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
  flingView.onFling((int) - velocityX);
  return true;
}

public void onFling(int paramFloat1) {
  if (offsetX > GalleryDemoActivity.deviceScreenWidth / 5) {
    if (fBitmap != null) {
      isFling = true;
      isFlingRight = true;
    }
  } else if (offsetX < -GalleryDemoActivity.deviceScreenWidth / 5) {
    if (nBitmap != null) {
      isFling = true;
      isFlingLeft = true;
    }
  }
  // 开始动画效果
  startAnimation(new MyAnimation());
}

@Override
public void draw(Canvas canvas) {
  Paint paint = new Paint();
  Rect rect = new Rect();
  canvas.drawColor(Color.BLACK);
  // 绘制当前图片
  if (bitmap != null) {
    int left = offsetX;
    int top = offsetY;
    int right = offsetX + GalleryDemoActivity.deviceScreenWidth;
    int bottom = offsetY + GalleryDemoActivity.deviceScreenHeight;
    rect.set(left, top, right, bottom);
    canvas.drawBitmap(bitmap, null, rect, paint);
  }
  // 绘制下一张图片
  if (offsetX < 0) { // 向左滑动
    if (nBitmap != null) {
      int left = GalleryDemoActivity.deviceScreenWidth + 15 + offsetX;
      int top = 0;
      int right = left + GalleryDemoActivity.deviceScreenWidth;
      int bottom = GalleryDemoActivity.deviceScreenHeight;
      rect.set(left, top, right, bottom);
      canvas.drawBitmap(nBitmap, null, rect, paint);
    }
  } else if (offsetX > 0) { // 向右滑动
    if (fBitmap != null) {
      int left = -GalleryDemoActivity.deviceScreenWidth - 15 + offsetX;
      int top = 0;
      int right = left + GalleryDemoActivity.deviceScreenWidth;
      int bottom = GalleryDemoActivity.deviceScreenHeight;
      rect.set(left, top, right, bottom);
      canvas.drawBitmap(fBitmap, null, rect, paint);
    }
  }
}

@Override
protected void onAnimationEnd() {
  if (isFlingRight) { // 向右滑动，position减1
    nBitmap = bitmap;
    bitmap = fBitmap;
    fBitmap = null;
    postion = postion - 1;
  } else if (isFlingLeft) { // 向左滑动，position加1
    fBitmap = bitmap;
    bitmap = nBitmap;
    nBitmap = null;
    postion = postion + 1;
  }
  isFlingRight = false;
  isFlingLeft = false;
  isFling = false;
  offsetX = 0;
  if (fBitmap == null && offsetX == 0) { // 如果前一张图片为空（向右滑），则重置前一张图片（position - 1）
    if (postion > 0) {
      fBitmap = getBitmap(postion - 1);
    }
  } else if (nBitmap == null && offsetX == 0) { // 如果后一张图片为空（向左滑），则重置后一张图片（position + 1）
    if (postion < bitmaps.length - 1) {
      nBitmap = getBitmap(postion + 1);
    }
  }
  clearAnimation();
}