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#!/usr/bin/env python3
"""
Animated Towers of Hanoi using Tk with optional bitmap file in background.
Usage: hanoi.py [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.
"""
from tkinter import Tk, Canvas
# 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 True:
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 True:
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 True:
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 True:
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)
def main():
import sys
# First argument is number of pegs, default 4
if sys.argv[1:]:
n = int(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()
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