Demo/tkinter/guido/brownian2.py

   1 # Brownian motion -- an example of a NON multi-threaded Tkinter program ;)
   2 # By Michele Simoniato, inspired by brownian.py
   3
   4 from Tkinter import *
   5 import random
   6 import sys
   7
   8 WIDTH = 400
   9 HEIGHT = 300
  10 SIGMA = 10
  11 BUZZ = 2
  12 RADIUS = 2
  13 LAMBDA = 10
  14 FILL = 'red'
  15
  16 stop = 0                                # Set when main loop exits
  17 root = None                             # main window
  18
  19 def particle(canvas):                   # particle = iterator over the moves
  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         try:
  28             canvas.move(p, dx, dy)
  29         except TclError:
  30             break
  31         else:
  32             yield None
  33
  34 def move(particle): # move the particle at random time
  35     particle.next()
  36     dt = random.expovariate(LAMBDA)
  37     root.after(int(dt*1000), move, particle)
  38
  39 def main():
  40     global root, stop
  41     root = Tk()
  42     canvas = Canvas(root, width=WIDTH, height=HEIGHT)
  43     canvas.pack(fill='both', expand=1)
  44     np = 30
  45     if sys.argv[1:]:
  46         np = int(sys.argv[1])
  47     for i in range(np):                  # start the dance
  48         move(particle(canvas))
  49     try:
  50         root.mainloop()
  51     finally:
  52         stop = 1
  53
  54 if __name__ == '__main__':
  55     main()