def draw(self, img, pixmapper, bounds):
        '''draw the trail'''
        for p in self.points:
            (px,py) = pixmapper(p)
            if px >= 0 and py >= 0 and px < img.width and py < img.height:
                cv.Circle(img, (px,py), 1, self.colour)
def draw ( self , img , pixmapper , bounds ) : for p in self . points : ( px , py ) = pixmapper ( p ) if px >= 0 and py >= 0 and px < img . width and py < img . height : cv . Circle ( img , ( px , py ) , 1 , self . colour )
draw the trail