convert2dashes added. not yet used.

Caveat: only runs on nodes of type path (not line, rect, polyline, polygon, circle, ellipse)

doc/ruida.md

@@ -15,7 +15,7 @@ The InkSvg class is implemented in src/inksvg.py and implements converting an SV
 Known limitations are:
 
 * Text rendering. Text elements are not represented in the output, but a warning is generated **"Warning: unable to draw text, please convert it to a path first."**
-* Dotted or dashed lines. They are rendered as solid lines. inkscape-silhouette has code to support this.
+* Dotted or dashed lines. They are rendered as solid lines. TODO: use src/convert2dashes.py from https://github.com/fablabnbg/inkscape-silhouette/pull/33/commits/dfa061352d0c211ada77da6860b74361ddf431b0
 
 class ThunderLaser
 ==================

src/convert2dashes.py

@@ -0,0 +1,84 @@
+#!/usr/bin/env python 
+
+# Extracted from inkscape extension; original comments below:
+'''
+This extension converts a path into a dashed line using 'stroke-dasharray'
+It is a modification of the file addnodes.py
+
+Copyright (C) 2005,2007 Aaron Spike, [email protected]
+Copyright (C) 2009 Alvin Penner, [email protected]
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+'''
+# local library
+import cubicsuperpath
+import bezmisc
+import simplestyle
+
+def tpoint((x1,y1), (x2,y2), t = 0.5):
+    return [x1+t*(x2-x1),y1+t*(y2-y1)]
+def cspbezsplit(sp1, sp2, t = 0.5):
+    m1=tpoint(sp1[1],sp1[2],t)
+    m2=tpoint(sp1[2],sp2[0],t)
+    m3=tpoint(sp2[0],sp2[1],t)
+    m4=tpoint(m1,m2,t)
+    m5=tpoint(m2,m3,t)
+    m=tpoint(m4,m5,t)
+    return [[sp1[0][:],sp1[1][:],m1], [m4,m,m5], [m3,sp2[1][:],sp2[2][:]]]
+def cspbezsplitatlength(sp1, sp2, l = 0.5, tolerance = 0.001):
+    bez = (sp1[1][:],sp1[2][:],sp2[0][:],sp2[1][:])
+    t = bezmisc.beziertatlength(bez, l, tolerance)
+    return cspbezsplit(sp1, sp2, t)
+def cspseglength(sp1,sp2, tolerance = 0.001):
+    bez = (sp1[1][:],sp1[2][:],sp2[0][:],sp2[1][:])
+    return bezmisc.bezierlength(bez, tolerance)    
+
+def splitPath(inkex, node):
+    dashes = []
+    style = simplestyle.parseStyle(node.get('style'))
+    if style.has_key('stroke-dasharray'):
+        if style['stroke-dasharray'].find(',') > 0:
+            dashes = [float (dash) for dash in style['stroke-dasharray'].split(',') if dash]
+    if dashes:
+        p = cubicsuperpath.parsePath(node.get('d'))
+        new = []
+        for sub in p:
+            idash = 0
+            dash = dashes[0]
+            length = 0
+            new.append([sub[0][:]])
+            i = 1
+            while i < len(sub):
+                dash = dash - length
+                length = cspseglength(new[-1][-1], sub[i])
+                while dash < length:
+                    new[-1][-1], next, sub[i] = cspbezsplitatlength(new[-1][-1], sub[i], dash/length)
+                    if idash % 2:           # create a gap
+                        new.append([next[:]])
+                    else:                   # splice the curve
+                        new[-1].append(next[:])
+                    length = length - dash
+                    idash = (idash + 1) % len(dashes)
+                    dash = dashes[idash]
+                if idash % 2:
+                    new.append([sub[i]])
+                else:
+                    new[-1].append(sub[i])
+                i+=1
+        node.set('d',cubicsuperpath.formatPath(new))
+        del style['stroke-dasharray']
+        node.set('style', simplestyle.formatStyle(style))
+        if node.get(inkex.addNS('type','sodipodi')):
+            del node.attrib[inkex.addNS('type', 'sodipodi')]