mightyscape-1.1-deprecated/extensions/fablabchemnitz/fablabchemnitz_clonesperspective.py

#!/usr/bin/env python3
import sys
import math
import inkex
from lxml import etree

class clonesPerspectiveEffect(inkex.Effect):
    def __init__(self):
        inkex.Effect.__init__(self)
        self.arg_parser.add_argument('--num', type = int, default = 5, help = 'Drag out center of rotation before calling')
        self.arg_parser.add_argument('--ratio', type = float, default = 0.9, help = 'Ratio of size of nearest neighbor to first.  Must be < 1')

    def effect(self):
        svg = self.document.getroot()
        num = int( self.options.num )
        ratio = float( self.options.ratio)

        if 1 != len(self.svg.selected) :
            inkex.errormsg("Select exactly 1 thing. Group if necessary")
            sys.exit(1)
        id = list(self.svg.selected.items())[0][0]
        sel = self.svg.selected[id]
        dic = sel.attrib
        try :
            tx = dic[inkex.addNS('transform-center-x','inkscape') ]
        except KeyError :
            tx = '0.'
        try :
            ty = dic[inkex.addNS('transform-center-y','inkscape') ]
        except KeyError : 
            ty = '0.'

        if float(tx) == 0. and float(ty) == 0. :
            inkex.errormsg("Center of rotation at center of object")
            sys.exit(1)
  
        bbox = sel.bounding_box()
        width =  bbox.height
        height = bbox.width
        cx = float(bbox.left) + 0.5 * width  #Find center of selected object
        cy = float(bbox.top) + 0.5 * height #Find center of selected object
        tx = float(tx)
        ty = float(ty)
        crat = 1.0
        otx = tx
        oty = ty

        parent = sel.getparent()
        j = parent.index(sel)
        for i in range(num) :
            crat *= ratio
            tx *= ratio
            ty *= ratio
            att = {
                "id" : self.svg.get_unique_id("clone" + id),
                inkex.addNS('href','xlink') : "#" + id,
                inkex.addNS('transform-center-x','inkscape') : str(tx),
                inkex.addNS('transform-center-y','inkscape') : str(ty),
                'transform' : ("matrix(%f,0,0,%f,%f,%f)" % (crat, crat,(1. - crat)*(cx + otx), (1. - crat)*(cy - oty))),
            "width" :  "100%",
            "height" : "100%",
            }
            parent.insert(j, etree.Element('use', att))

clonesPerspectiveEffect().run()