1#!/usr/bin/env python3
2"""       turtle-example-suite:
3
4            tdemo_paint.py
5
6A simple  event-driven paint program
7
8- left mouse button moves turtle
9- middle mouse button changes color
10- right mouse button toogles betweem pen up
11(no line drawn when the turtle moves) and
12pen down (line is drawn). If pen up follows
13at least two pen-down moves, the polygon that
14includes the starting point is filled.
15 -------------------------------------------
16 Play around by clicking into the canvas
17 using all three mouse buttons.
18 -------------------------------------------
19          To exit press STOP button
20 -------------------------------------------
21"""
22from turtle import *
23
24def switchupdown(x=0, y=0):
25    if pen()["pendown"]:
26        end_fill()
27        up()
28    else:
29        down()
30        begin_fill()
31
32def changecolor(x=0, y=0):
33    global colors
34    colors = colors[1:]+colors[:1]
35    color(colors[0])
36
37def main():
38    global colors
39    shape("circle")
40    resizemode("user")
41    shapesize(.5)
42    width(3)
43    colors=["red", "green", "blue", "yellow"]
44    color(colors[0])
45    switchupdown()
46    onscreenclick(goto,1)
47    onscreenclick(changecolor,2)
48    onscreenclick(switchupdown,3)
49    return "EVENTLOOP"
50
51if __name__ == "__main__":
52    msg = main()
53    print(msg)
54    mainloop()
55