Function isNull

qcustomplot/qcustomplot.h:411–411

  QPointF toPointF() const { return QPointF(mX, mY); }
  
  bool isNull() const { return qIsNull(mX) && qIsNull(mY); }
  void normalize();
  QCPVector2D normalized() const;
  QCPVector2D perpendicular() const { return QCPVector2D(-mY, mX); }