# Animated Towers of Hanoi using Tk with optional bitmap file in

# background.

#

# Usage: tkhanoi [n [bitmapfile]]

#

# n is the number of pieces to animate; default is 4, maximum 15.

#

# The bitmap file can be any X11 bitmap file (look in

# /usr/include/X11/bitmaps for samples); it is displayed as the

# background of the animation.  Default is no bitmap.

# This uses Steen Lumholt's Tk interface

from Tkinter import *

# Basic Towers-of-Hanoi algorithm: move n pieces from a to b, using c

# as temporary.  For each move, call report()

def hanoi(n, a, b, c, report):

    if n <= 0: return

    hanoi(n-1, a, c, b, report)

    report(n, a, b)

    hanoi(n-1, c, b, a, report)

# The graphical interface

class Tkhanoi:

    # Create our objects

    def __init__(self, n, bitmap = None):

        self.n = n

        self.tk = tk = Tk()

        self.canvas = c = Canvas(tk)

        c.pack()

        width, height = tk.getint(c['width']), tk.getint(c['height'])

        # Add background bitmap

        if bitmap:

            self.bitmap = c.create_bitmap(width//2, height//2,

                                          bitmap=bitmap,

                                          foreground='blue')

        # Generate pegs

        pegwidth = 10

        pegheight = height//2

        pegdist = width//3

        x1, y1 = (pegdist-pegwidth)//2, height*1//3

        x2, y2 = x1+pegwidth, y1+pegheight

        self.pegs = []

        p = c.create_rectangle(x1, y1, x2, y2, fill='black')

        self.pegs.append(p)

        x1, x2 = x1+pegdist, x2+pegdist

        p = c.create_rectangle(x1, y1, x2, y2, fill='black')

        self.pegs.append(p)

        x1, x2 = x1+pegdist, x2+pegdist

        p = c.create_rectangle(x1, y1, x2, y2, fill='black')

        self.pegs.append(p)

        self.tk.update()

        # Generate pieces

        pieceheight = pegheight//16

        maxpiecewidth = pegdist*2//3

        minpiecewidth = 2*pegwidth

        self.pegstate = [[], [], []]

        self.pieces = {}

        x1, y1 = (pegdist-maxpiecewidth)//2, y2-pieceheight-2

        x2, y2 = x1+maxpiecewidth, y1+pieceheight

        dx = (maxpiecewidth-minpiecewidth) // (2*max(1, n-1))

        for i in range(n, 0, -1):

            p = c.create_rectangle(x1, y1, x2, y2, fill='red')

            self.pieces[i] = p

            self.pegstate[0].append(i)

            x1, x2 = x1 + dx, x2-dx

            y1, y2 = y1 - pieceheight-2, y2-pieceheight-2

            self.tk.update()

            self.tk.after(25)

    # Run -- never returns

    def run(self):

        while 1:

            hanoi(self.n, 0, 1, 2, self.report)

            hanoi(self.n, 1, 2, 0, self.report)

            hanoi(self.n, 2, 0, 1, self.report)

            hanoi(self.n, 0, 2, 1, self.report)

            hanoi(self.n, 2, 1, 0, self.report)

            hanoi(self.n, 1, 0, 2, self.report)

    # Reporting callback for the actual hanoi function

    def report(self, i, a, b):

        if self.pegstate[a][-1] != i: raise RuntimeError # Assertion

        del self.pegstate[a][-1]

        p = self.pieces[i]

        c = self.canvas

        # Lift the piece above peg a

        ax1, ay1, ax2, ay2 = c.bbox(self.pegs[a])

        while 1:

            x1, y1, x2, y2 = c.bbox(p)

            if y2 < ay1: break

            c.move(p, 0, -1)

            self.tk.update()

        # Move it towards peg b

        bx1, by1, bx2, by2 = c.bbox(self.pegs[b])

        newcenter = (bx1+bx2)//2

        while 1:

            x1, y1, x2, y2 = c.bbox(p)

            center = (x1+x2)//2

            if center == newcenter: break

            if center > newcenter: c.move(p, -1, 0)

            else: c.move(p, 1, 0)

            self.tk.update()

        # Move it down on top of the previous piece

        pieceheight = y2-y1

        newbottom = by2 - pieceheight*len(self.pegstate[b]) - 2

        while 1:

            x1, y1, x2, y2 = c.bbox(p)

            if y2 >= newbottom: break

            c.move(p, 0, 1)

            self.tk.update()

        # Update peg state

        self.pegstate[b].append(i)

# Main program

def main():

    import sys, string

    # First argument is number of pegs, default 4

    if sys.argv[1:]:

        n = string.atoi(sys.argv[1])

    else:

        n = 4

    # Second argument is bitmap file, default none

    if sys.argv[2:]:

        bitmap = sys.argv[2]

        # Reverse meaning of leading '@' compared to Tk

        if bitmap[0] == '@': bitmap = bitmap[1:]

        else: bitmap = '@' + bitmap

    else:

        bitmap = None

    # Create the graphical objects...

    h = Tkhanoi(n, bitmap)

    # ...and run!

    h.run()

# Call main when run as script

if __name__ == '__main__':

    main()