A simple touch tracer

from pymt import *

class Tracer(MTWidget):
    def on_touch_down(self, touch):
        touch.userdata['points'] = list(touch.pos)

    def on_touch_move(self, touch):
        touch.userdata['points'].extend(touch.pos)

    def draw(self):
        # draw a black background
        set_color(0, 0, 0)
        drawRectangle(size=getWindow().size)
        # draw lines
        set_color(1, 1, 1)
        for touch in getCurrentTouches():
            drawLine(touch.userdata['points'])

runTouchApp(Tracer())