offsetAt method

Implementation

int? offsetAt(Offset point, {double maxDistance = 48}) {
  int cursor = 0;
  int? bestRun;
  int bestCursor = 0;
  double bestDistance = double.infinity;
  for (int i = 0; i < runs.length; i++) {
    final UDocTextRun run = runs[i];
    final Rect area = run.rect;
    final double dx = point.dx < area.left ? area.left - point.dx : (point.dx > area.right ? point.dx - area.right : 0);
    final double dy = point.dy < area.top ? area.top - point.dy : (point.dy > area.bottom ? point.dy - area.bottom : 0);
    final double distance = dx * dx + dy * dy * 4;
    if (distance < bestDistance) {
      bestDistance = distance;
      bestRun = i;
      bestCursor = cursor;
    }
    cursor += run.text.length + 1;
  }
  if (bestRun == null || bestDistance > maxDistance * maxDistance) return null;
  return bestCursor + runs[bestRun].offsetAt(point);
}