Is it feasible to draw a polygon around a Qwt line curve with the mouse ? Because I want to save the polygon points (the scale values not the pixels) and be able later to load them and draw them in order to validate if a line curve fits inside the polygon points (both visually and programmatically : true/false).

If someone has already done this or has a better idea to validate if data fits within some borders (defined by a polygon), I'll take it.