calculatePosition method

void calculatePosition()

call this function when you want to recalculate the positions of the nodes for example if you want to restore the postion after dragging the items around but don't forget to setState after calcutions this function is called automatically when you change the items list

Implementation

void calculatePosition() {
  for (Node<E> node in _nodes.where((element) => _getLevel(element) == 1)) {
    _calculateNP(node);
  }
}