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#! /usr/bin/env python
# Simulate "electrons" migrating across the screen.
# An optional bitmap file in can be in the background.
#
# Usage: electrons [n [bitmapfile]]
#
# n is the number of electrons to animate; default is 30.
#
# The bitmap file can be any X11 bitmap file (look in
# /usr/include/X11/bitmaps for samples); it is displayed as the
# background of the animation. Default is no bitmap.
from tkinter import *
import random
# The graphical interface
class Electrons:
# Create our objects
def __init__(self, n, bitmap = None):
self.n = n
self.tk = tk = Tk()
self.canvas = c = Canvas(tk)
c.pack()
width, height = tk.getint(c['width']), tk.getint(c['height'])
# Add background bitmap
if bitmap:
self.bitmap = c.create_bitmap(width/2, height/2,
bitmap=bitmap,
foreground='blue')
self.pieces = []
x1, y1, x2, y2 = 10,70,14,74
for i in range(n):
p = c.create_oval(x1, y1, x2, y2, fill='red')
self.pieces.append(p)
y1, y2 = y1 +2, y2 + 2
self.tk.update()
def random_move(self, n):
c = self.canvas
for p in self.pieces:
x = random.choice(range(-2,4))
y = random.choice(range(-3,4))
c.move(p, x, y)
self.tk.update()
# Run -- allow 500 movemens
def run(self):
try:
for i in range(500):
self.random_move(self.n)
except TclError:
try:
self.tk.destroy()
except TclError:
pass
# Main program
def main():
import sys, string
# First argument is number of electrons, default 30
if sys.argv[1:]:
n = string.atoi(sys.argv[1])
else:
n = 30
# Second argument is bitmap file, default none
if sys.argv[2:]:
bitmap = sys.argv[2]
# Reverse meaning of leading '@' compared to Tk
if bitmap[0] == '@': bitmap = bitmap[1:]
else: bitmap = '@' + bitmap
else:
bitmap = None
# Create the graphical objects...
h = Electrons(n, bitmap)
# ...and run!
h.run()
# Call main when run as script
if __name__ == '__main__':
main()
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