1 # Brownian motion -- an example of a multi-threaded Tkinter program.

     2 

     3 from Tkinter import *

     4 import random

     5 import threading

     6 import time

     7 import sys

     8 

     9 WIDTH = 400

    10 HEIGHT = 300

    11 SIGMA = 10

    12 BUZZ = 2

    13 RADIUS = 2

    14 LAMBDA = 10

    15 FILL = 'red'

    16 

    17 stop = 0                                # Set when main loop exits

    18 

    19 def particle(canvas):

    20     r = RADIUS

    21     x = random.gauss(WIDTH/2.0, SIGMA)

    22     y = random.gauss(HEIGHT/2.0, SIGMA)

    23     p = canvas.create_oval(x-r, y-r, x+r, y+r, fill=FILL)

    24     while not stop:

    25         dx = random.gauss(0, BUZZ)

    26         dy = random.gauss(0, BUZZ)

    27         dt = random.expovariate(LAMBDA)

    28         try:

    29             canvas.move(p, dx, dy)

    30         except TclError:

    31             break

    32         time.sleep(dt)

    33 

    34 def main():

    35     global stop

    36     root = Tk()

    37     canvas = Canvas(root, width=WIDTH, height=HEIGHT)

    38     canvas.pack(fill='both', expand=1)

    39     np = 30

    40     if sys.argv[1:]:

    41         np = int(sys.argv[1])

    42     for i in range(np):

    43         t = threading.Thread(target=particle, args=(canvas,))

    44         t.start()

    45     try:

    46         root.mainloop()

    47     finally:

    48         stop = 1

    49 

    50 main()