addDot method
Implementation
void addDot(Offset offset) {
  if (_lines.isEmpty) {
    return;
  }
  _lines[_selectPathIndex].line.add(offset);
  notifyListeners();
}void addDot(Offset offset) {
  if (_lines.isEmpty) {
    return;
  }
  _lines[_selectPathIndex].line.add(offset);
  notifyListeners();
}