SVG Sierpinski Carpet Generator

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
License:
Copyright (c) 2007-2010 Kerim Mansour
All rights reserved.

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice,
  this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
  this list of conditions and the following disclaimer in the documentation 
  and/or other materials provided with the distribution.
* Neither the name of the author nor the names of other contributors 
  may be used to endorse or promote products derived from this software without 
  specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, 
OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 
OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
"""

from pysvg.structure import svg
from pysvg.builders import ShapeBuilder


def divideRect(x,y,length, svgDocument, maxResolution=3):
    step=length/3
    #first we set the white rectangle in the middle
    sb =ShapeBuilder()
    white_rectangle = sb.createRect(x+step,y+step,step,step,fill='#FFF')
    svgDocument.addElement(white_rectangle)
    #if the size of the rectangle is still greater than the minimum resolution continue with the division
    if length>maxResolution:
        #left 3 rectangles
        divideRect(x, y, length/3, svgDocument, maxResolution)
        divideRect(x, y+step, length/3, svgDocument, maxResolution)
        divideRect(x, y+step*2, length/3, svgDocument, maxResolution)
        #upper and lower middle rectangle
        divideRect(x+step, y, length/3, svgDocument, maxResolution)
        divideRect(x+step, y+step*2, length/3, svgDocument, maxResolution)
        #right 3 rectangles
        divideRect(x+step*2, y, length/3, svgDocument, maxResolution)
        divideRect(x+step*2, y+step, length/3, svgDocument, maxResolution)
        divideRect(x+step*2, y+step*2, length/3, svgDocument, maxResolution)


length = 2187 # some big multiple of 3
svgDocument=svg()

#create basic black background rectangle
sb = ShapeBuilder()
black_rectangle = sb.createRect(0,0,length,length,fill='000')
svgDocument.addElement(black_rectangle)
divideRect(0, 0, length, svgDocument, maxResolution=30)

svgDocument.save('../tests/testoutput/sierpinski.svg')