Demo/tkinter/guido/brownian.py

   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()