is it possible to gesture draw like Circle, Cross or triangle?

i got a simple code from touch source like

if (newPoint.X >= previousPoint.X && newPoint.Y >= previousPoint.Y) midpoint = newPoint; // if we're stroking up (moving right x and up y [y axis is flipped]) else if (newPoint.X >= previousPoint.X && newPoint.Y <= previousPoint.Y)

but i wonder is there a way to when i draw square , says me its square!

thanks