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,
  70                                                {'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-y1-2
 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
 127 # Main program
 128 def main():
 129         import sys, string
 130
 131         # First argument is number of pegs, default 4
 132         if sys.argv[1:]:
 133                 n = string.atoi(sys.argv[1])
 134         else:
 135                 n = 4
 136
 137         # Second argument is bitmap file, default none
 138         if sys.argv[2:]:
 139                 bitmap = sys.argv[2]
 140                 # Reverse meaning of leading '@' compared to Tk
 141                 if bitmap[0] == '@': bitmap = bitmap[1:]
 142                 else: bitmap = '@' + bitmap
 143         else:
 144                 bitmap = None
 145
 146         # Create the graphical objects...
 147         h = Tkhanoi(n, bitmap)
 148
 149         # ...and run!
 150         h.run()
 151
 152
 153 # Call main when run as script
 154 if __name__ == '__main__':
 155         main()