share/extensions/convert2dashes.py

   1 #!/usr/bin/env python
   2 '''
   3 This extension converts a path into a dashed line using 'stroke-dasharray'
   4 It is a modification of the file addnodes.py
   5
   6 Copyright (C) 2005,2007 Aaron Spike, aaron@ekips.org
   7 Copyright (C) 2009 Alvin Penner, penner@vaxxine.com
   8
   9 This program is free software; you can redistribute it and/or modify
  10 it under the terms of the GNU General Public License as published by
  11 the Free Software Foundation; either version 2 of the License, or
  12 (at your option) any later version.
  13
  14 This program is distributed in the hope that it will be useful,
  15 but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 GNU General Public License for more details.
  18
  19 You should have received a copy of the GNU General Public License
  20 along with this program; if not, write to the Free Software
  21 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  22 '''
  23
  24 import inkex, cubicsuperpath, bezmisc, simplestyle
  25
  26 def tpoint((x1,y1), (x2,y2), t = 0.5):
  27     return [x1+t*(x2-x1),y1+t*(y2-y1)]
  28 def cspbezsplit(sp1, sp2, t = 0.5):
  29     m1=tpoint(sp1[1],sp1[2],t)
  30     m2=tpoint(sp1[2],sp2[0],t)
  31     m3=tpoint(sp2[0],sp2[1],t)
  32     m4=tpoint(m1,m2,t)
  33     m5=tpoint(m2,m3,t)
  34     m=tpoint(m4,m5,t)
  35     return [[sp1[0][:],sp1[1][:],m1], [m4,m,m5], [m3,sp2[1][:],sp2[2][:]]]
  36 def cspbezsplitatlength(sp1, sp2, l = 0.5, tolerance = 0.001):
  37     bez = (sp1[1][:],sp1[2][:],sp2[0][:],sp2[1][:])
  38     t = bezmisc.beziertatlength(bez, l, tolerance)
  39     return cspbezsplit(sp1, sp2, t)
  40 def cspseglength(sp1,sp2, tolerance = 0.001):
  41     bez = (sp1[1][:],sp1[2][:],sp2[0][:],sp2[1][:])
  42     return bezmisc.bezierlength(bez, tolerance)
  43
  44 class SplitIt(inkex.Effect):
  45     def __init__(self):
  46         inkex.Effect.__init__(self)
  47
  48     def effect(self):
  49         for id, node in self.selected.iteritems():
  50             if node.tag == inkex.addNS('path','svg'):
  51                 dashes = []
  52                 style = simplestyle.parseStyle(node.get('style'))
  53                 if style.has_key('stroke-dasharray'):
  54                     if style['stroke-dasharray'].find(',') > 0:
  55                         dashes = [float (dash) for dash in style['stroke-dasharray'].split(',')]
  56                 if dashes:
  57                     p = cubicsuperpath.parsePath(node.get('d'))
  58                     new = []
  59                     for sub in p:
  60                         idash = 0
  61                         dash = dashes[0]
  62                         length = 0
  63                         new.append([sub[0][:]])
  64                         i = 1
  65                         while i < len(sub):
  66                             dash = dash - length
  67                             length = cspseglength(new[-1][-1], sub[i])
  68                             while dash < length:
  69                                 new[-1][-1], next, sub[i] = cspbezsplitatlength(new[-1][-1], sub[i], dash/length)
  70                                 if idash % 2:           # create a gap
  71                                     new.append([next[:]])
  72                                 else:                   # splice the curve
  73                                     new[-1].append(next[:])
  74                                 length = length - dash
  75                                 idash = (idash + 1) % len(dashes)
  76                                 dash = dashes[idash]
  77                             if idash % 2:
  78                                 new.append([sub[i]])
  79                             else:
  80                                 new[-1].append(sub[i])
  81                             i+=1
  82                     node.set('d',cubicsuperpath.formatPath(new))
  83
  84 if __name__ == '__main__':
  85     e = SplitIt()
  86     e.affect()
  87
  88
  89 # vim: expandtab shiftwidth=4 tabstop=8 softtabstop=4 fileencoding=utf-8 textwidth=99