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
  13 from 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()
  18 def 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
  26 class 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
 127 def 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
 153 if __name__ == '__main__':
 154     main()