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# Brownian motion -- an example of a multi-threaded Tkinter program.
from Tkinter import *
import random
import threading
import time
import sys
WIDTH = 400
HEIGHT = 300
SIGMA = 10
BUZZ = 2
RADIUS = 2
LAMBDA = 10
FILL = 'red'
stop = 0 # Set when main loop exits
lock = threading.Lock() # Protects the random generator
def particle(canvas):
r = RADIUS
lock.acquire()
try:
x = random.gauss(WIDTH/2.0, SIGMA)
y = random.gauss(HEIGHT/2.0, SIGMA)
finally:
lock.release()
p = canvas.create_oval(x-r, y-r, x+r, y+r, fill=FILL)
while not stop:
lock.acquire()
try:
dx = random.gauss(0, BUZZ)
dy = random.gauss(0, BUZZ)
dt = random.expovariate(LAMBDA)
finally:
lock.release()
try:
canvas.move(p, dx, dy)
except TclError:
break
time.sleep(dt)
def main():
global stop
root = Tk()
canvas = Canvas(root, width=WIDTH, height=HEIGHT)
canvas.pack(fill='both', expand=1)
np = 30
if sys.argv[1:]:
np = int(sys.argv[1])
for i in range(np):
t = threading.Thread(target=particle, args=(canvas,))
t.start()
try:
root.mainloop()
finally:
stop = 1
main()
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