/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
14from Tkinter import *
15import random
16
17
18# The graphical interface
19class 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
64def 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
90if __name__ == '__main__':
91    main()