Demo/tkinter/guido/electrons.py

   1 #! /usr/bin/env python
   2
   3 # Simulate "electrons" migrating across the screen.
   4 # An optional bitmap file in can be in the background.
   5 #
   6 # Usage: electrons [n [bitmapfile]]
   7 #
   8 # n is the number of electrons to animate; default is 30.
   9 #
  10 # The bitmap file can be any X11 bitmap file (look in
  11 # /usr/include/X11/bitmaps for samples); it is displayed as the
  12 # background of the animation.  Default is no bitmap.
  13
  14 from Tkinter import *
  15 import random
  16
  17
  18 # The graphical interface
  19 class Electrons:
  20
  21     # Create our objects
  22     def __init__(self, n, bitmap = None):
  23         self.n = n
  24         self.tk = tk = Tk()
  25         self.canvas = c = Canvas(tk)
  26         c.pack()
  27         width, height = tk.getint(c['width']), tk.getint(c['height'])
  28
  29         # Add background bitmap
  30         if bitmap:
  31             self.bitmap = c.create_bitmap(width/2, height/2,
  32                                           bitmap=bitmap,
  33                                           foreground='blue')
  34
  35         self.pieces = []
  36         x1, y1, x2, y2 = 10,70,14,74
  37         for i in range(n):
  38             p = c.create_oval(x1, y1, x2, y2, fill='red')
  39             self.pieces.append(p)
  40             y1, y2 = y1 +2, y2 + 2
  41         self.tk.update()
  42
  43     def random_move(self, n):
  44         c = self.canvas
  45         for p in self.pieces:
  46             x = random.choice(range(-2,4))
  47             y = random.choice(range(-3,4))
  48             c.move(p, x, y)
  49         self.tk.update()
  50
  51     # Run -- allow 500 movemens
  52     def run(self):
  53         try:
  54             for i in range(500):
  55                 self.random_move(self.n)
  56         except TclError:
  57             try:
  58                 self.tk.destroy()
  59             except TclError:
  60                 pass
  61
  62
  63 # Main program
  64 def main():
  65     import sys, string
  66
  67     # First argument is number of electrons, default 30
  68     if sys.argv[1:]:
  69         n = string.atoi(sys.argv[1])
  70     else:
  71         n = 30
  72
  73     # Second argument is bitmap file, default none
  74     if sys.argv[2:]:
  75         bitmap = sys.argv[2]
  76         # Reverse meaning of leading '@' compared to Tk
  77         if bitmap[0] == '@': bitmap = bitmap[1:]
  78         else: bitmap = '@' + bitmap
  79     else:
  80         bitmap = None
  81
  82     # Create the graphical objects...
  83     h = Electrons(n, bitmap)
  84
  85     # ...and run!
  86     h.run()
  87
  88
  89 # Call main when run as script
  90 if __name__ == '__main__':
  91     main()