[Android] Save JPEG with lesser quality the bigger it is, especially useful to reduce image upload time.

BitmapUtils.java

private static final int MB = 1000000; // 1MB in bytes
private static final int MIN_SIZE = 3; // in MB
private static final int MAX_SIZE = 20; // in MB
private static final int MAX_QUALITY = 100;
private static final int MIN_QUALITY = 10;
private static final int NORMAL_QUALITY = 90;

/**
 * Gets a bitmap and saves it as jpeg.
 *
 * @return the handle of the saved file.
 */
public static File saveBitmapOnDisk(Context context, String fileName, Bitmap bitmap) throws IOException {
  // can I write on the cache? IOException otherwise.
  final File file = FileUtils.findBestStoringPlace(context, fileName);

  final int sizeInMb = bitmap.getByteCount() / MB;
  final int quality;
  if (BuildConfig.DEBUG || sizeInMb > MAX_SIZE) {
    quality = MIN_QUALITY;
  } else if (sizeInMb <= MIN_SIZE) {
    quality = NORMAL_QUALITY;
  } else {
    // In order to reduce upload time we need to reduce the image size.
    // Therefore, quality should be inversely proportional to the image size
    // (bigger images=>worse quality), the following formula is obtained
    // from this proportion: MAX_SIZE : MAX_QUALITY = sizeInMb : quality
    quality = MAX_QUALITY - ((sizeInMb * MAX_QUALITY) / MAX_SIZE);
  }
    
  // overwrites the old file if it exists.
  final OutputStream os = new FileOutputStream(file, false);
  bitmap.compress(Bitmap.CompressFormat.JPEG, quality, os);
  os.flush();
  os.close();
  return file;
}