1#!/usr/bin/env python3
2
3"""
4Animated Towers of Hanoi using Tk with optional bitmap file in background.
5
6Usage: hanoi.py [n [bitmapfile]]
7
8n is the number of pieces to animate; default is 4, maximum 15.
9
10The bitmap file can be any X11 bitmap file (look in /usr/include/X11/bitmaps for
11samples); it is displayed as the background of the animation.  Default is no
12bitmap.
13"""
14
15from tkinter import Tk, Canvas
16
17# Basic Towers-of-Hanoi algorithm: move n pieces from a to b, using c
18# as temporary.  For each move, call report()
19def hanoi(n, a, b, c, report):
20    if n <= 0: return
21    hanoi(n-1, a, c, b, report)
22    report(n, a, b)
23    hanoi(n-1, c, b, a, report)
24
25
26# The graphical interface
27class Tkhanoi:
28
29    # Create our objects
30    def __init__(self, n, bitmap = None):
31        self.n = n
32        self.tk = tk = Tk()
33        self.canvas = c = Canvas(tk)
34        c.pack()
35        width, height = tk.getint(c['width']), tk.getint(c['height'])
36
37        # Add background bitmap
38        if bitmap:
39            self.bitmap = c.create_bitmap(width//2, height//2,
40                                          bitmap=bitmap,
41                                          foreground='blue')
42
43        # Generate pegs
44        pegwidth = 10
45        pegheight = height//2
46        pegdist = width//3
47        x1, y1 = (pegdist-pegwidth)//2, height*1//3
48        x2, y2 = x1+pegwidth, y1+pegheight
49        self.pegs = []
50        p = c.create_rectangle(x1, y1, x2, y2, fill='black')
51        self.pegs.append(p)
52        x1, x2 = x1+pegdist, x2+pegdist
53        p = c.create_rectangle(x1, y1, x2, y2, fill='black')
54        self.pegs.append(p)
55        x1, x2 = x1+pegdist, x2+pegdist
56        p = c.create_rectangle(x1, y1, x2, y2, fill='black')
57        self.pegs.append(p)
58        self.tk.update()
59
60        # Generate pieces
61        pieceheight = pegheight//16
62        maxpiecewidth = pegdist*2//3
63        minpiecewidth = 2*pegwidth
64        self.pegstate = [[], [], []]
65        self.pieces = {}
66        x1, y1 = (pegdist-maxpiecewidth)//2, y2-pieceheight-2
67        x2, y2 = x1+maxpiecewidth, y1+pieceheight
68        dx = (maxpiecewidth-minpiecewidth) // (2*max(1, n-1))
69        for i in range(n, 0, -1):
70            p = c.create_rectangle(x1, y1, x2, y2, fill='red')
71            self.pieces[i] = p
72            self.pegstate[0].append(i)
73            x1, x2 = x1 + dx, x2-dx
74            y1, y2 = y1 - pieceheight-2, y2-pieceheight-2
75            self.tk.update()
76            self.tk.after(25)
77
78    # Run -- never returns
79    def run(self):
80        while 1:
81            hanoi(self.n, 0, 1, 2, self.report)
82            hanoi(self.n, 1, 2, 0, self.report)
83            hanoi(self.n, 2, 0, 1, self.report)
84            hanoi(self.n, 0, 2, 1, self.report)
85            hanoi(self.n, 2, 1, 0, self.report)
86            hanoi(self.n, 1, 0, 2, self.report)
87
88    # Reporting callback for the actual hanoi function
89    def report(self, i, a, b):
90        if self.pegstate[a][-1] != i: raise RuntimeError # Assertion
91        del self.pegstate[a][-1]
92        p = self.pieces[i]
93        c = self.canvas
94
95        # Lift the piece above peg a
96        ax1, ay1, ax2, ay2 = c.bbox(self.pegs[a])
97        while 1:
98            x1, y1, x2, y2 = c.bbox(p)
99            if y2 < ay1: break
100            c.move(p, 0, -1)
101            self.tk.update()
102
103        # Move it towards peg b
104        bx1, by1, bx2, by2 = c.bbox(self.pegs[b])
105        newcenter = (bx1+bx2)//2
106        while 1:
107            x1, y1, x2, y2 = c.bbox(p)
108            center = (x1+x2)//2
109            if center == newcenter: break
110            if center > newcenter: c.move(p, -1, 0)
111            else: c.move(p, 1, 0)
112            self.tk.update()
113
114        # Move it down on top of the previous piece
115        pieceheight = y2-y1
116        newbottom = by2 - pieceheight*len(self.pegstate[b]) - 2
117        while 1:
118            x1, y1, x2, y2 = c.bbox(p)
119            if y2 >= newbottom: break
120            c.move(p, 0, 1)
121            self.tk.update()
122
123        # Update peg state
124        self.pegstate[b].append(i)
125
126
127def main():
128    import sys
129
130    # First argument is number of pegs, default 4
131    if sys.argv[1:]:
132        n = int(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