processFinderPatternInfo method

DetectorResult processFinderPatternInfo(FinderPatternInfo info)

Implementation

DetectorResult processFinderPatternInfo(FinderPatternInfo info) {
  final topLeft = info.topLeft;
  final topRight = info.topRight;
  final bottomLeft = info.bottomLeft;

  final moduleSize = calculateModuleSize(topLeft, topRight, bottomLeft);
  if (moduleSize < 1.0) {
    throw NotFoundException.instance;
  }
  final dimension =
      _computeDimension(topLeft, topRight, bottomLeft, moduleSize);
  final provisionalVersion =
      Version.getProvisionalVersionForDimension(dimension);
  final modulesBetweenFPCenters = provisionalVersion.dimensionForVersion - 7;

  AlignmentPattern? alignmentPattern;
  // Anything above version 1 has an alignment pattern
  if (provisionalVersion.alignmentPatternCenters.isNotEmpty) {
    // Guess where a "bottom right" finder pattern would have been
    final bottomRightX = topRight.x - topLeft.x + bottomLeft.x;
    final bottomRightY = topRight.y - topLeft.y + bottomLeft.y;

    // Estimate that alignment pattern is closer by 3 modules
    // from "bottom right" to known top left location
    final correctionToTopLeft = 1.0 - 3.0 / modulesBetweenFPCenters;
    final estAlignmentX =
        (topLeft.x + correctionToTopLeft * (bottomRightX - topLeft.x))
            .toInt();
    final estAlignmentY =
        (topLeft.y + correctionToTopLeft * (bottomRightY - topLeft.y))
            .toInt();

    // Kind of arbitrary -- expand search radius before giving up
    for (int i = 4; i <= 16; i <<= 1) {
      try {
        alignmentPattern = findAlignmentInRegion(
          moduleSize,
          estAlignmentX,
          estAlignmentY,
          i.toDouble(),
        );
        break;
      } on NotFoundException catch (_) {
        // try next round
      }
    }
    // If we didn't find alignment pattern... well try anyway without it
  }

  final transform = _createTransform(
    topLeft,
    topRight,
    bottomLeft,
    alignmentPattern,
    dimension,
  );

  final bits = _sampleGrid(_image, transform, dimension);

  late List<ResultPoint> points;
  if (alignmentPattern == null) {
    points = [bottomLeft, topLeft, topRight];
  } else {
    points = [bottomLeft, topLeft, topRight, alignmentPattern];
  }
  return DetectorResult(bits, points);
}