android 图片的压缩

private static int calculateInSampleSize(
            BitmapFactory.Options options, int reqWidth, int reqHeight) {

        final int height = options.outHeight;
        final int width = options.outWidth;
        int inSampleSize = 1;

if (height > reqHeight || width > reqWidth) {
            if (height > reqHeight && reqHeight != 0) {
                inSampleSize = (int) Math.floor((double) height / (double) reqHeight);
            }

            int tmp = 0;

            if (width > reqWidth && reqWidth != 0) {
                tmp = (int) Math.floor((double) width / (double) reqWidth);
            }

            inSampleSize = Math.max(inSampleSize, tmp);

        }
        int roundedSize;
        if (inSampleSize <= 8) {
            roundedSize = 1;
            while (roundedSize < inSampleSize) {
                roundedSize <<= 1;
            }
        } else {
            roundedSize = (inSampleSize + 7) / 8 * 8;
        }

        return roundedSize;
    }