1# Animated Towers of Hanoi using Tk with optional bitmap file in
2# background.
3#
4# Usage: tkhanoi [n [bitmapfile]]
5#
6# n is the number of pieces to animate; default is 4, maximum 15.
7#
8# The bitmap file can be any X11 bitmap file (look in
9# /usr/include/X11/bitmaps for samples); it is displayed as the
10# background of the animation.  Default is no bitmap.
11
12# This uses Steen Lumholt's Tk interface
13from Tkinter import *
14
15
16# Basic Towers-of-Hanoi algorithm: move n pieces from a to b, using c
17# as temporary.  For each move, call report()
18def hanoi(n, a, b, c, report):
19    if n <= 0: return
20    hanoi(n-1, a, c, b, report)
21    report(n, a, b)
22    hanoi(n-1, c, b, a, report)
23
24
25# The graphical interface
26class Tkhanoi:
27
28    # Create our objects
29    def __init__(self, n, bitmap = None):
30        self.n = n
31        self.tk = tk = Tk()
32        self.canvas = c = Canvas(tk)
33        c.pack()
34        width, height = tk.getint(c['width']), tk.getint(c['height'])
35
36        # Add background bitmap
37        if bitmap:
38            self.bitmap = c.create_bitmap(width//2, height//2,
39                                          bitmap=bitmap,
40                                          foreground='blue')
41
42        # Generate pegs
43        pegwidth = 10
44        pegheight = height//2
45        pegdist = width//3
46        x1, y1 = (pegdist-pegwidth)//2, height*1//3
47        x2, y2 = x1+pegwidth, y1+pegheight
48        self.pegs = []
49        p = c.create_rectangle(x1, y1, x2, y2, fill='black')
50        self.pegs.append(p)
51        x1, x2 = x1+pegdist, x2+pegdist
52        p = c.create_rectangle(x1, y1, x2, y2, fill='black')
53        self.pegs.append(p)
54        x1, x2 = x1+pegdist, x2+pegdist
55        p = c.create_rectangle(x1, y1, x2, y2, fill='black')
56        self.pegs.append(p)
57        self.tk.update()
58
59        # Generate pieces
60        pieceheight = pegheight//16
61        maxpiecewidth = pegdist*2//3
62        minpiecewidth = 2*pegwidth
63        self.pegstate = [[], [], []]
64        self.pieces = {}
65        x1, y1 = (pegdist-maxpiecewidth)//2, y2-pieceheight-2
66        x2, y2 = x1+maxpiecewidth, y1+pieceheight
67        dx = (maxpiecewidth-minpiecewidth) // (2*max(1, n-1))
68        for i in range(n, 0, -1):
69            p = c.create_rectangle(x1, y1, x2, y2, fill='red')
70            self.pieces[i] = p
71            self.pegstate[0].append(i)
72            x1, x2 = x1 + dx, x2-dx
73            y1, y2 = y1 - pieceheight-2, y2-pieceheight-2
74            self.tk.update()
75            self.tk.after(25)
76
77    # Run -- never returns
78    def run(self):
79        while 1:
80            hanoi(self.n, 0, 1, 2, self.report)
81            hanoi(self.n, 1, 2, 0, self.report)
82            hanoi(self.n, 2, 0, 1, self.report)
83            hanoi(self.n, 0, 2, 1, self.report)
84            hanoi(self.n, 2, 1, 0, self.report)
85            hanoi(self.n, 1, 0, 2, self.report)
86
87    # Reporting callback for the actual hanoi function
88    def report(self, i, a, b):
89        if self.pegstate[a][-1] != i: raise RuntimeError # Assertion
90        del self.pegstate[a][-1]
91        p = self.pieces[i]
92        c = self.canvas
93
94        # Lift the piece above peg a
95        ax1, ay1, ax2, ay2 = c.bbox(self.pegs[a])
96        while 1:
97            x1, y1, x2, y2 = c.bbox(p)
98            if y2 < ay1: break
99            c.move(p, 0, -1)
100            self.tk.update()
101
102        # Move it towards peg b
103        bx1, by1, bx2, by2 = c.bbox(self.pegs[b])
104        newcenter = (bx1+bx2)//2
105        while 1:
106            x1, y1, x2, y2 = c.bbox(p)
107            center = (x1+x2)//2
108            if center == newcenter: break
109            if center > newcenter: c.move(p, -1, 0)
110            else: c.move(p, 1, 0)
111            self.tk.update()
112
113        # Move it down on top of the previous piece
114        pieceheight = y2-y1
115        newbottom = by2 - pieceheight*len(self.pegstate[b]) - 2
116        while 1:
117            x1, y1, x2, y2 = c.bbox(p)
118            if y2 >= newbottom: break
119            c.move(p, 0, 1)
120            self.tk.update()
121
122        # Update peg state
123        self.pegstate[b].append(i)
124
125
126# Main program
127def main():
128    import sys, string
129
130    # First argument is number of pegs, default 4
131    if sys.argv[1:]:
132        n = string.atoi(sys.argv[1])
133    else:
134        n = 4
135
136    # Second argument is bitmap file, default none
137    if sys.argv[2:]:
138        bitmap = sys.argv[2]
139        # Reverse meaning of leading '@' compared to Tk
140        if bitmap[0] == '@': bitmap = bitmap[1:]
141        else: bitmap = '@' + bitmap
142    else:
143        bitmap = None
144
145    # Create the graphical objects...
146    h = Tkhanoi(n, bitmap)
147
148    # ...and run!
149    h.run()
150
151
152# Call main when run as script
153if __name__ == '__main__':
154    main()
155