dispatchRect method

@override Uint8List dispatchRect(Uint8List data, int width, int height, Rect rect,)

Implementation

@override
Uint8List dispatchRect(Uint8List data, int width, int height, Rect rect) {
  final newByte = Uint8List.fromList(data);
  final tranByte = translationScale.dispatch(data, width, height, rect);

  final stepX = 2;
  final stepY = 2;

  for (int startH = rect.top; startH < rect.bottom; startH += stepY) {
    for (int startW = rect.left; startW < rect.right; startW += stepX) {
      int oriAverage = 0;
      int tranAverage = 0;
      int min = 256;
      for (int i = startH; i < startH + stepY; i++) {
        for (int j = startW; j < startW + stepX; j++) {
          oriAverage += newByte[i * width + j];
          tranAverage += tranByte[i * width + j];
          if (tranByte[i * width + j] < min) {
            min = tranByte[i * width + j];
          }
        }
      }

      if (oriAverage <= tranAverage) {
        continue;
      }

      for (int i = startH; i < startH + stepY; i++) {
        //System.arraycopy(tranByte, i * width + start_w, newByte,
        //    i * width + start_w, start_w + stepX - start_w);
        List.copyRange(
          newByte,
          i * width + startW,
          tranByte,
          i * width + startW,
          startW + stepX + i * width,
        );
      }
    }
  }
  return newByte;
}