压缩图片到指定大小

 public static Bitmap zoomImage(Bitmap bgimage, double newWidth,
              double newHeight) {
      // 获取这个图片的宽和高
      float width = bgimage.getWidth();
      float height = bgimage.getHeight();
      // 创建操作图片用的matrix对象
      Matrix matrix = new Matrix();
      // 计算宽高缩放率
      float scaleWidth = ((float) newWidth) / width;
      float scaleHeight = ((float) newHeight) / height;
      // 缩放图片动作
      matrix.postScale(scaleWidth, scaleHeight);
      Bitmap bitmap = Bitmap.createBitmap(bgimage, 0, 0, (int) width,
                      (int) height, matrix, true);
      return bitmap;
}