markSegment method

int markSegment({ required Offset start, required Offset end, required Size size, required double brushWidth, })

Implementation

int markSegment({
  required Offset start,
  required Offset end,
  required Size size,
  required double brushWidth,
}) {
  if (size.width <= 0 || size.height <= 0 || brushWidth <= 0) return 0;
  final cellWidth = size.width / columns;
  final cellHeight = size.height / rows;
  final cellRadius =
      math.sqrt(cellWidth * cellWidth + cellHeight * cellHeight) / 2;
  final radius = brushWidth / 2 + cellRadius;
  final minX = math.max(
    0,
    ((math.min(start.dx, end.dx) - radius) / cellWidth).floor(),
  );
  final maxX = math.min(
    columns - 1,
    ((math.max(start.dx, end.dx) + radius) / cellWidth).floor(),
  );
  final minY = math.max(
    0,
    ((math.min(start.dy, end.dy) - radius) / cellHeight).floor(),
  );
  final maxY = math.min(
    rows - 1,
    ((math.max(start.dy, end.dy) + radius) / cellHeight).floor(),
  );
  var added = 0;
  for (var y = minY; y <= maxY; y++) {
    for (var x = minX; x <= maxX; x++) {
      final center = Offset((x + 0.5) * cellWidth, (y + 0.5) * cellHeight);
      if (_distanceToSegment(center, start, end) > radius) continue;
      final index = y * columns + x;
      if (_cells[index]) continue;
      _cells[index] = true;
      _covered++;
      added++;
    }
  }
  return added;
}