decode method

@override Result decode(BinaryBitmap image, [ DecodeHint? hints ])

Locates and decodes a barcode in some format within an image. This method also accepts hints, each possibly associated to some data, which may help the implementation decode.

@param image image of barcode to decode @param hints passed as a Map from DecodeHintType to arbitrary data. The meaning of the data depends upon the hint type. The implementation may or may not do anything with these hints. @return String which the barcode encodes @throws NotFoundException if no potential barcode is found @throws ChecksumException if a potential barcode is found but does not pass its checksum @throws FormatException if a potential barcode is found but format is invalid

Implementation

@override
Result decode(BinaryBitmap image, [DecodeHint? hints]) {
  final width = image.width;
  final height = image.height;
  final halfWidth = width ~/ 2;
  final halfHeight = height ~/ 2;

  try {
    // No need to call makeAbsolute as results will be relative to original top left here
    return _delegate.decode(image.crop(0, 0, halfWidth, halfHeight), hints);
  } on NotFoundException catch (_) {
    // continue
  }

  try {
    final result = _delegate.decode(
      image.crop(halfWidth, 0, halfWidth, halfHeight),
      hints,
    );
    _makeAbsolute(result.resultPoints, halfWidth, 0);
    return result;
  } on NotFoundException catch (_) {
    // continue
  }

  try {
    final result = _delegate.decode(
      image.crop(0, halfHeight, halfWidth, halfHeight),
      hints,
    );
    _makeAbsolute(result.resultPoints, 0, halfHeight);
    return result;
  } on NotFoundException catch (_) {
    // continue
  }

  try {
    final result = _delegate.decode(
      image.crop(halfWidth, halfHeight, halfWidth, halfHeight),
      hints,
    );
    _makeAbsolute(result.resultPoints, halfWidth, halfHeight);
    return result;
  } on NotFoundException catch (_) {
    // continue
  }

  final quarterWidth = halfWidth ~/ 2;
  final quarterHeight = halfHeight ~/ 2;
  final center =
      image.crop(quarterWidth, quarterHeight, halfWidth, halfHeight);
  final result = _delegate.decode(center, hints);
  _makeAbsolute(result.resultPoints, quarterWidth, quarterHeight);
  return result;
}