def export_drawing(self,evo_img):
        with evo_img.canvas.before:
            PushMatrix()
            Scale(origin=self.center, x=8,y=8)
            evo_img.export_to_png("/tmp/IMG_{}.png".format(time.strftime("%Y%m%d_%H%M%S")))
        with evo_img.canvas.after:
            PopMatrix()

 '''
     Button:
        id: save_btn
        text: "Export"
        on_press: root.export_drawing(evo_img)
'''