+ /// Compute the distance between points
+ /// \param theFirstPnt a point value of the out point attribute
+ /// \param theCurrentPnt a point of the current widget
+ /// \return a double value
+ virtual double computeValue(const std::shared_ptr<GeomAPI_Pnt2d>& theFirstPnt,
+ const std::shared_ptr<GeomAPI_Pnt2d>& theCurrentPnt);