findAlignmentInRegion method

AlignmentPattern findAlignmentInRegion(double overallEstModuleSize, int estAlignmentX, int estAlignmentY, double allowanceFactor,)

Attempts to locate an alignment pattern in a limited region of the image, which is guessed to contain it. This method uses [AlignmentPattern].

@param overallEstModuleSize estimated module size so far @param estAlignmentX x coordinate of center of area probably containing alignment pattern @param estAlignmentY y coordinate of above @param allowanceFactor number of pixels in all directions to search from the center @return AlignmentPattern if found, or null otherwise @throws NotFoundException if an unexpected error occurs during detection

Implementation

//@protected
AlignmentPattern findAlignmentInRegion(
  double overallEstModuleSize,
  int estAlignmentX,
  int estAlignmentY,
  double allowanceFactor,
) {
  // Look for an alignment pattern (3 modules in size) around where it
  // should be
  final allowance = (allowanceFactor * overallEstModuleSize).toInt();
  final alignmentAreaLeftX = math.max(0, estAlignmentX - allowance);
  final alignmentAreaRightX =
      math.min(_image.width - 1, estAlignmentX + allowance);
  if (alignmentAreaRightX - alignmentAreaLeftX < overallEstModuleSize * 3) {
    throw NotFoundException.instance;
  }

  final alignmentAreaTopY = math.max(0, estAlignmentY - allowance);
  final alignmentAreaBottomY =
      math.min(_image.height - 1, estAlignmentY + allowance);
  if (alignmentAreaBottomY - alignmentAreaTopY < overallEstModuleSize * 3) {
    throw NotFoundException.instance;
  }

  final alignmentFinder = AlignmentPatternFinder(
    _image,
    alignmentAreaLeftX,
    alignmentAreaTopY,
    alignmentAreaRightX - alignmentAreaLeftX,
    alignmentAreaBottomY - alignmentAreaTopY,
    overallEstModuleSize,
    _resultPointCallback,
  );
  return alignmentFinder.find();
}