How do you save a drawline and dot only?

Hello, it is possible to save drawlines and dots from canvas ? and how to work it out ? i dont want to save the whole canvas...it is because when i use crop or resize from taifun image extension and want to back to the drawing sections, the last drawline and dots is gone.

what about save all the points (x and y) in a list, then redraw the lines/points when needed?