/Demo/tkinter/guido/hanoi.py

  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()