1  #!/usr/bin/env python3
       2  
       3  """
       4  Animated Towers of Hanoi using Tk with optional bitmap file in background.
       5  
       6  Usage: hanoi.py [n [bitmapfile]]
       7  
       8  n is the number of pieces to animate; default is 4, maximum 15.
       9  
      10  The bitmap file can be any X11 bitmap file (look in /usr/include/X11/bitmaps for
      11  samples); it is displayed as the background of the animation.  Default is no
      12  bitmap.
      13  """
      14  
      15  from 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()
      19  def 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
      27  class ESC[4;38;5;81mTkhanoi:
      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 True:
      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 True:
      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 True:
     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 True:
     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  def 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
     153  if __name__ == '__main__':
     154      main()