massive rework of input_stl extension

extensions/fablabchemnitz/input_stl.inx

@@ -4,40 +4,52 @@
     <id>fablabchemnitz.de.input_stl</id>
     <param name="tab" type="notebook">
         <page name="options" gui-text="Options">
+            <param name="inputfile" type="path" gui-text="Input file" filetypes="obj,off,ply,stl" mode="file">/your/object/file.stl</param>
             <param name="layer_height" type="string" gui-text="Layer height [mm]:">1.0</param>
             <param name="rx" type="float" precision="1" min="-360.0" max="360.0" gui-text="3D-Rotate X-Axis [deg]:">0</param>
             <param name="ry" type="float" precision="1" min="-360.0" max="360.0" gui-text="3D-Rotate Y-Axis [deg]:">0</param>
             <param name="numbers" type="bool" gui-text="Add layer numbers">false</param>
             <param name="center" type="bool" gui-text="Add center marks">false</param>
+            <param name="stroke_width" type="float" min="0" max="100" gui-text="Stroke width (px):">2</param>
+            <param name="path_color" type="color" appearance="colorbutton" gui-text="Path color">879076607</param>
+            <param name="fill_color" type="color" appearance="colorbutton" gui-text="Fill color">1943148287</param>
+            <param name="use_fill_color" type="bool" gui-text="Use fill color">false</param>
+            <param name="tone_down" type="optiongroup" appearance="combo" gui-text="Town down opacity for each layer">
+               <option value="regular">regular</option>
+               <option value="front_to_back">front to back</option>
+               <option value="back_to_front">back to front</option>
+            </param>
         </page>
         <page name="slic3r" gui-text="Slic3r Settings">
-            <param name="slic3r_cmd" type="string" gui-text="Slic3r Command">slic3r</param>
+            <param name="slic3r_cmd" type="path" mode="file" gui-text="Slic3r Command">slic3r</param>
             <label xml:space="preserve">The slic3r command name depends on your operating system, and how slic3r was installed.
 Typical values are:
 
-$HOME/Downloads/Slic3r-1.3.0-x86_64.AppImage	(Linux)
+$HOME/Downloads/Slic3r-1.3.0-x86_64.AppImage (Linux)
-$HOME/Slic3r/Slic3r-console.exe 		(Windows)</label>
+%USERPROFILE%/Slic3r/Slic3r-console.exe (Windows)</label>
         </page>
         <page name="help" gui-text="Help">
             <label xml:space="preserve">- Projects an STL file on the X-Y plane by cutting the objects into "slices".
 - Each "slice" is a group of polygons, with a label indicating its z position.
 - The polygons are converted to paths for better editing in inkscape.
 
-- Use Object -&gt; Rows &amp; Columns ... distribute the slices in a grid.
+- Use Object -&gt; Rows &amp; Columns ... distribute the slices in a grid.</label>
 
-https://github.com/jnweiger/inkscape-input-stl
+<label appearance="url">https://github.com/jnweiger/inkscape-input-stl</label>
-(C) 2018 by Jürgen Weigert &lt;jnweiger@gmail.com&gt;
+<label xml:space="preserve">(C) 2018 by Jürgen Weigert &lt;jnweiger@gmail.com&gt; and others.
-Version 0.6
 
 Distribute under GPLv2 or ask.</label>
+<label appearance="url">https://slic3r.org/download</label>
         </page>
     </param>
-    <input>
+    <effect>
-        <extension>.stl</extension>
+        <object-type>all</object-type>
-        <mimetype>application/sla</mimetype>
+        <effects-menu>
-        <filetypename>Stereolitography File (*.stl)</filetypename>
+            <submenu name="FabLab Chemnitz">
-        <filetypetooltip>Import STL Files</filetypetooltip>
+                <submenu name="Import/Export/Transfer" />
-    </input>
+            </submenu>
+        </effects-menu>
+    </effect>
     <script>
         <command location="inx" interpreter="python">input_stl.py</command>
     </script>

extensions/fablabchemnitz/input_stl.py

@@ -1,31 +1,45 @@
 #!/usr/bin/env python3
-# input-stl.py
+'''
-# (C) 2018 Juergen Weigert <juergen@fabmail.org>, distribute under GPLv2 or ask
+(C) 2018 Juergen Weigert <juergen@fabmail.org>, distribute under GPLv2 or ask
-#
-# This is an input extension for inkscape to read STL files.
-#
-# Requires: (python-lxml | python3-lxml), slic3r
-# For optional(!) rotation support:
-#   Requires: (python-numpy-stl | python3-numpy-stl)
-#   If you get ImportError: cannot import name 'mesh'
-#   although an stl module is installed, then you have the wrong stl module.
-#   Try 'pip3 uninstall stl; pip3 install numpy-stl'
-#
-# 2018-12-22 jw, v0.1 Initial draught
-#                v0.1 First working standalone tool.
-# 2018-12-26 jw, v0.3 Mesh rotation support via numpy-stl. Fully optional.
-#                v0.4 Works fine as an inkscape input extension under Linux.
-# 2019-03-01 jw, v0.5 numbers and center option added.
-# 2019-07-17 jw, v0.6 fixed ry rotation.
-#
-# FIXME: should use svg_pathstats(path_d): to compute bounding boxes.
 
-from __future__ import print_function
+This is an input extension for inkscape to read STL files.
-import sys, os, re, argparse
+
-import subprocess, tempfile
+Requires: (python-lxml | python3-lxml), slic3r
+For optional(!) rotation support:
+  Requires: (python-numpy-stl | python3-numpy-stl)
+  If you get ImportError: cannot import name 'mesh'
+  although an stl module is installed, then you have the wrong stl module.
+  Try 'pip3 uninstall stl; pip3 install numpy-stl'
+
+2018-12-22 jw, v0.1 Initial draught
+                       v0.1 First working standalone tool.
+2018-12-26 jw, v0.3 Mesh rotation support via numpy-stl. Fully optional.
+                       v0.4 Works fine as an inkscape input extension under Linux.
+2019-03-01 jw, v0.5 numbers and center option added.
+2019-07-17 jw, v0.6 fixed ry rotation.
+
+2021-05-14 - Mario Voigt: 
+    - changed extension to support ply,off,obj,stl by using OpenMesh
+    - moved extension to sub menu structure (allows preview)
+    - added different options
+
+#ToDos
+ * Make it available through PrusaSlic3r
+ * FIXME: should use svg_pathstats(path_d): to compute bounding boxes.
+'''
+import sys
+import os
+import re
+import subprocess
 from lxml import etree
 from subprocess import Popen, PIPE
-_version = '0.6'
+import inkex
+from inkex import Color
+import tempfile
+import openmesh as om
+import stl #numpy-stl lib
+import numpy
+import math
 
 sys_platform = sys.platform.lower()
 if sys_platform.startswith('win'):
@@ -37,260 +51,264 @@ else:   # Linux
   if not os.path.exists(slic3r):
     slic3r = 'slic3r'
 
-parser = argparse.ArgumentParser(description='convert an STL file to a nice SVG for inkscape. The STL object is projected onto the X-Y plane.')
+class InputSTL(inkex.EffectExtension):
-parser.add_argument('-l', '--layer_height', default=None, help='slic3r layer height, probably in mm. Default: per slic3r config')
+    
-parser.add_argument('--rx', default=None, type=float, help='Rotate STL object around X-Axis before importing.')
+    def add_arguments(self, pars):
-parser.add_argument('--ry', default=None, type=float, help='Rotate STL object around Y-Axis before importing.')
+        pars.add_argument('--tab')
-parser.add_argument('--numbers', default='false', help='Add layer numbers.')
-parser.add_argument('--center', default='false', help='Add center marks.')
-parser.add_argument('--stdout', '--tab', default=None, help=argparse.SUPPRESS)
-parser.add_argument('-s', '--slic3r-cmd', '--slic3r_cmd', default=slic3r, help='Command to invoke slic3r. Default is "'+slic3r+'"')
-parser.add_argument('-o', '--output', default=None, help='SVG output file name or "-" for stdout. Default: Name derived from STL input.') 
-parser.add_argument('stlfile', help='STL input file to convert to SVG with the same name, but ".svg" suffix.')
 
-args = parser.parse_args()
+        pars.add_argument('--inputfile', help='STL input file to convert to SVG with the same name, but ".svg" suffix.')
+        pars.add_argument('-l', '--layer_height', default=None, help='slic3r layer height, probably in mm. Default: per slic3r config')
+        pars.add_argument('--rx', default=None, type=float, help='Rotate STL object around X-Axis before importing.')
+        pars.add_argument('--ry', default=None, type=float, help='Rotate STL object around Y-Axis before importing.')
+        pars.add_argument('--numbers', type=inkex.Boolean, default=False, help='Add layer numbers.')
+        pars.add_argument('--center', type=inkex.Boolean, default=False, help='Add center marks.')
+        pars.add_argument("--stroke_width", type=float, default=2.0, help="Stroke width (px)")
+        pars.add_argument('--path_color', type=Color, default='879076607', help="Path color")
+        pars.add_argument("--fill_color", type=Color, default='1943148287', help="Fill color")
+        pars.add_argument("--use_fill_color", type=inkex.Boolean, default=False, help="Use fill color")
+        pars.add_argument("--tone_down",  default="regular", help="Town down opacity for each layer")
+      
+        pars.add_argument('-s', '--slic3r-cmd', '--slic3r_cmd', default="slic3r", help="Command to invoke slic3r.")
 
-# input-stl.inx advertises use of '$HOME' -- windows has HOMEPATH instead of HOME
+    def effect(self):             
-home = os.environ.get('HOME', os.environ.get('HOMEPATH', 'NO-HOME'))
+        args = self.options
-#args.slic3r_cmd = re.sub('^\$HOME(PATH)?', home, args.slic3r_cmd)
+        inputfile = args.inputfile    
+        outputfilebase = os.path.splitext(os.path.basename(inputfile))[0]
+        converted_inputfile = os.path.join(tempfile.gettempdir(), outputfilebase + ".stl")
+        if not os.path.exists(inputfile):
+                inkex.utils.debug("The input file does not exist.")
+                exit(1) 
+        om.write_mesh(converted_inputfile, om.read_trimesh(inputfile)) #read + convert     # might throw "[STLWriter] : Warning non-triangle data!"
+        args.inputfile = converted_inputfile #overwrite
 
-if sys_platform.startswith('win'):
+        # input-stl.inx advertises use of '$HOME' -- windows has HOMEPATH instead of HOME
-  # assert we run the commandline version of slic3r
+        home = os.environ.get('HOME', os.environ.get('HOMEPATH', 'NO-HOME'))
-  args.slic3r_cmd = re.sub('slic3r(\.exe)?$', 'slic3r-console.exe', args.slic3r_cmd, flags=re.I)
+        #args.slic3r_cmd = re.sub('^\$HOME(PATH)?', home, args.slic3r_cmd)
+        
+        if sys_platform.startswith('win'):
+            # assert we run the commandline version of slic3r
+            args.slic3r_cmd = re.sub('slic3r(\.exe)?$', 'slic3r-console.exe', args.slic3r_cmd, flags=re.I)
+        
 
-stlfile = args.stlfile
+        tmp_inputfile = None
-tmpstlfile = None
+     
+        if args.rx is not None and abs(args.rx) < 0.01: args.rx = None
+        if args.ry is not None and abs(args.ry) < 0.01: args.ry = None
+        
+        if args.rx or args.ry:
+            try:        
+                mesh = stl.Mesh.from_file(inputfile)
+                if args.rx: mesh.rotate([1.0, 0.0, 0.0], math.radians(float(args.rx)))
+                if args.ry: mesh.rotate([0.0, 1.0, 0.0], math.radians(float(args.ry)))
+                inputfile = tmp_inputfile = tempfile.gettempdir() + os.path.sep + 'ink-stl-' + str(os.getpid()) + '.stl'
+                mesh.save(inputfile)
+            except Exception as e:
+                inkex.utils.debug("Rotate failed: " + str(e))
+            
+        svgfile = re.sub('\.stl', '.svg', args.inputfile, flags=re.IGNORECASE)
+                        
+        cmd = [args.slic3r_cmd, '--version']
+        try:
+            proc = subprocess.Popen(cmd, shell=False, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        except OSError as e:
+            hint="Maybe use --slic3r-cmd option?"
+            inkex.utils.debug("{0}\nCommand failed: errno={1} {2}\n\n{3}".format(' '.join(cmd), e.errno, e.strerror, hint), file=sys.stderr)
+            sys.exit(1)
+        stdout, stderr = proc.communicate()
+        
+        # option --layer-height does not work. We use --scale instead...
+        scale = 1/float(args.layer_height)
+        cmd = [args.slic3r_cmd, '--no-gui']
+        if args.layer_height is not None:
+            cmd += ['--scale', str(scale), '--first-layer-height', '0.1mm']     # args.layer_height+'mm']
+        cmd += ['--export-svg', '-o', svgfile, inputfile]
+        
+        magic = 10    # layer width seems to be 0.1mm ???
+        
+        def scale_points(pts, scale):
+            """ str='276.422496,309.4 260.209984,309.4 260.209984,209.03 276.422496,209.03'
+            """
+            return re.sub('\d*\.\d*', lambda x: str(float(x.group(0))*scale*magic), pts)
+        
+        
+        ## CAUTION: keep svg_pathstats() in sync with inkscape-centerlinetrace
+        def svg_pathstats(path_d):
+            """ calculate statistics from an svg path:
+                    length (measuring bezier splines as straight lines through the handles).
+                    points (all, including duplicates)
+                    segments (number of not-connected!) path segments.
+                    simple bounding box (ignoring curves of splines, but inclding handles.)
+            """
+            xmin = 1e99
+            ymin = 1e99
+            xmax = -1e99
+            ymax = -1e99
+            p_points = 0
+            p_length = 0
+            p_segments = 0
+        
+            path_d = path_d.lower()
+            for p in path_d.split('m'):
+        
+                pp = re.sub('[cl,]', ' ', p)
+                pp,closed = re.subn('z\s*$','',pp)
+                xy = pp.split()
+                if len(xy) < 2:
+                    # inkex.utils.debug(len(pp))
+                    # inkex.utils.debug("short path error")
+                    continue
+                x0 = float(xy[0])
+                y0 = float(xy[1])
+                if x0 > xmax: xmax = x0
+                if x0 < xmin: xmin = x0
+                if y0 > ymax: ymax = y0
+                if y0 < ymin: ymin = y0
+        
+                p_points += 1
+                x = xy[2::2]
+                y = xy[3::2]
+                if len(x):
+                    p_segments += 1
+                    if closed:
+                        x.extend(x0)
+                        y.extend(y0)
+        
+                for i in range(len(x)):
+                    p_points += 1
+                    dx = float(x[i]) - x0
+                    dy = float(y[i]) - y0
+                    p_length += math.sqrt( dx * dx + dy * dy )
+                    x0,y0 = float(x[i]),float(y[i])
+                    if x0 > xmax: xmax = x0
+                    if x0 < xmin: xmin = x0
+                    if y0 > ymax: ymax = y0
+                    if y0 < ymin: ymin = y0
+        
+            return { 'points':p_points, 'segments':p_segments, 'length':p_length, 'bbox': (xmin,ymin, xmax, ymax) }
+        
+        
+        def bbox_info(slic3r, file):
+            cmd = [ slic3r, '--no-gui', '--info', file ]
+            p = Popen(cmd, stdout=PIPE, stderr=PIPE)
+            out, err = p.communicate()
+            if len(err):
+                raise ValueError(err)
+        
+            bb = {}
+            for l in out.decode().split("\n"):
+                m = re.match('((min|max)_[xyz])\s*=\s*(.*)', l)
+                if m: bb[m.group(1)] = float(m.group(3))
+            if (len(bb) != 6):
+                raise ValueError("slic3r --info did not return 6 elements for bbox")
+            return bb
+        
+        if args.center is not False:
+            bb = bbox_info(args.slic3r_cmd, inputfile)
+            # Ouch: bbox info gives us stl coordinates. slic3r translates them into svg px using 75dpi.
+            cx = (-bb['min_x'] + bb['max_x']) * 0.5 * 1/scale * magic * 25.4 / 75
+            cy = (-bb['min_y'] + bb['max_y']) * 0.5 * 1/scale * magic * 25.4 / 75  
 
-if args.rx is not None and abs(args.rx) < 0.01: args.rx = None
+        try:
-if args.ry is not None and abs(args.ry) < 0.01: args.ry = None
+            proc = subprocess.Popen(cmd, shell=False, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        except OSError as e:
+            raise OSError("{0}\nCommand failed: errno={1} {2}".format(' '.join(cmd), e.errno, e.strerror))
+        stdout, stderr = proc.communicate()
+        
+        if tmp_inputfile and os.path.exists(tmp_inputfile):
+            os.unlink(tmp_inputfile)
+        
+        if not b'Done.' in stdout:
+            inkex.utils.debug("Command failed: {0}".format(' '.join(cmd)))
+            inkex.utils.debug("OUT: " + str(stdout))
+            inkex.utils.debug("ERR: " + str(stderr))
+            sys.exit(1)
+        
+        # slic3r produces correct svg files, but with polygons instead of paths, and with undefined strokes.
+        # When opened with inkscape, most lines are invisible and polygons cannot be edited.
+        # To fix these issues, we postprocess the svg file:
+        # * replace polygon nodes with corresponding path nodes.
+        # * replace style attribute in polygon nodes with one that has a black stroke
+        
+        stream = open(svgfile, 'r')
+        p = etree.XMLParser(huge_tree=True)
+        doc = etree.parse(stream, parser=p)
+        stream.close()
+        
+        ## To change the document units to mm, insert directly after the root node:
+        # e.tag = '{http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd}namedview'
+        # e.attrib['id'] = "base"
+        # e.attrib['{http://www.inkscape.org/namespaces/inkscape}document-units'] = "mm"
+        
+        layercount = 0
+        for e in doc.iterfind('//{*}g'):
+            if e.attrib['{http://slic3r.org/namespaces/slic3r}z'] and e.attrib['id']:
+                e.attrib['{http://www.inkscape.org/namespaces/inkscape}label'] = e.attrib['id'] + ' slic3r:z=' + e.attrib['{http://slic3r.org/namespaces/slic3r}z']
+                del e.attrib['{http://slic3r.org/namespaces/slic3r}z']
+                # for some fun with our inkscape-paths2openscad extension, add sibling to e:
+                # <svg:desc id="descpoly60">Depth: 1mm\nOffset: 31mm</svg:desc>
+                desc = etree.Element('{http://www.w3.org/2000/svg}desc')
+                desc.attrib['id'] = 'descl'+str(layercount)
+                desc.text = "Depth: %.2fmm\nRaise: %.2fmm\n" % (1/scale, layercount/scale)
+                e.append(desc)
+                layercount+=1
+                if args.numbers is True:
+                    num = etree.Element('{http://www.w3.org/2000/svg}text')
+                    num.attrib['id'] = 'textnum'+str(layercount)
+                    num.attrib['x'] = str(layercount*2)
+                    num.attrib['y'] = str(layercount*4+10)
+                    num.attrib['style'] = 'fill:#00FF00;fill-opacity:1;stroke:#00FF00;font-family:FreeSans;font-size:10pt;stroke-opacity:1;stroke-width:0.1'
+                    num.text = "%d" % layercount
+                    e.append(num)
+                if args.center is True:
+                    cc = etree.Element('{http://www.w3.org/2000/svg}path')
+                    cc.attrib['id'] = 'ccross'+str(layercount)
+                    cc.attrib['style'] = 'fill:none;fill-opacity:1;stroke:#0000FF;font-family:FreeSans;font-size:10pt;stroke-opacity:1;stroke-width:0.1'
+                    cc.attrib['d'] = 'M %s,%s v 10 M %s,%s h 10 M %s,%s h 4' % (cx, cy-5,  cx-5, cy,  cx-2, cy+5)
+                    e.append(cc)
+       
+        totalPolygoncount = 0
+        for e in doc.iterfind('//{*}polygon'):
+            totalPolygoncount += 1
+            
+        polygoncount = 0
+        
+        if args.use_fill_color is False:
+            fill = "none"
+        else:
+            fill = args.fill_color
+        
+        for e in doc.iterfind('//{*}polygon'):
+            polygoncount += 1
+            if args.tone_down == "front_to_back":
+                stroke_and_fill_opacity = polygoncount / totalPolygoncount
+            elif args.tone_down == "back_to_front":
+                stroke_and_fill_opacity = 1 - (polygoncount / totalPolygoncount)
+            elif args.tone_down == "regular":
+                stroke_and_fill_opacity = 1.0
+            else:
+                inkex.utils.debug("Error: unkown town down option")
+                exit(1)
+            # e.tag = '{http://www.w3.org/2000/svg}polygon'
+            # e.attrib = {'{http://slic3r.org/namespaces/slic3r}type': 'contour', 'points': '276.422496,309.4 260.209984,309.4 260.209984,209.03 276.422496,209.03', 'style': 'fill: white'}
+            e.tag = re.sub('polygon$', 'path', e.tag)
+            e.attrib['id'] = 'polygon%d' % polygoncount
+            e.attrib['{http://www.inkscape.org/namespaces/inkscape}connector-curvature'] = '0'
+            e.attrib['style'] = 'fill:{};fill-opacity:{};stroke:{};stroke-opacity:{};stroke-width:{}'.format(fill, stroke_and_fill_opacity, args.path_color, stroke_and_fill_opacity, args.stroke_width)
+            e.attrib['d'] = 'M ' + re.sub(' ', ' L ', scale_points(e.attrib['points'], 1/scale)) + ' Z'
+            del e.attrib['points']
+            if e.attrib.get('{http://slic3r.org/namespaces/slic3r}type') == 'contour':
+                # remove contour, but keep all slic3r:type='hole', whatever it is worth later.
+                del e.attrib['{http://slic3r.org/namespaces/slic3r}type']
+        
+        etree.cleanup_namespaces(doc.getroot(), top_nsmap={
+            'inkscape': 'http://www.inkscape.org/namespaces/inkscape',
+            'sodipodi': 'http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd'})
+    
+        #inkex.utils.debug("{0}: {1} polygons in {2} layers converted to paths.".format(svgfile, polygoncount, layercount))
 
-if args.rx or args.ry:
+        stl_group = self.document.getroot().add(inkex.Group(id=self.svg.get_unique_id("slic3r-stl-input-"))) #make a new group at root level
-  try:
+        for element in doc.getroot().iter("{http://www.w3.org/2000/svg}g"):
-    import numpy, stl, math
+            stl_group.append(element)
 
-    mesh = stl.Mesh.from_file(stlfile)
+if __name__ == '__main__':
-    if args.rx: mesh.rotate([1.0, 0.0, 0.0], math.radians(float(args.rx)))
+    InputSTL().run()
-    if args.ry: mesh.rotate([0.0, 1.0, 0.0], math.radians(float(args.ry)))
-    stlfile = tmpstlfile = tempfile.gettempdir() + os.path.sep + 'ink-stl-' + str(os.getpid()) + '.stl'
-    mesh.save(stlfile)
-  except Exception as e:
-    print("Rotate failed: " + str(e), file=sys.stderr)
-
-if args.output == '-': args.stdout = True
-
-if args.stdout:
-  svgfile = tempfile.gettempdir() + os.path.sep + 'ink-stl-' + str(os.getpid()) + '.svg'
-else:
-  svgfile = re.sub('\.stl', '.svg', args.stlfile, flags=re.IGNORECASE)
-  if args.output is not None: svgfile = args.output
-
-cmd = [args.slic3r_cmd, '--version']
-try:
-  proc = subprocess.Popen(cmd, shell=False, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-except OSError as e:
-  if args.stdout:
-    hint="Check your slic3r command setting in the second tab of the STL Input dialog."
-  else:
-    hint="Maybe use --slic3r-cmd option?"
-  print("{0}\nCommand failed: errno={1} {2}\n\n{3}".format(' '.join(cmd), e.errno, e.strerror, hint), file=sys.stderr)
-  sys.exit(1)
-stdout, stderr = proc.communicate()
-
-# option --layer-height does not work. We use --scale instead...
-scale = 1/float(args.layer_height)
-cmd = [args.slic3r_cmd, '--no-gui']
-if args.layer_height is not None:
-  cmd += ['--scale', str(scale), '--first-layer-height', '0.1mm']     # args.layer_height+'mm']
-cmd += ['--export-svg', '-o', svgfile, stlfile]
-
-magic = 10    # layer width seems to be 0.1mm ???
-
-def scale_points(pts, scale):
-  """ str='276.422496,309.4 260.209984,309.4 260.209984,209.03 276.422496,209.03'
-  """
-  return re.sub('\d*\.\d*', lambda x: str(float(x.group(0))*scale*magic), pts)
-
-
-## CAUTION: keep svg_pathstats() in sync with inkscape-centerlinetrace
-def svg_pathstats(path_d):
-  """ calculate statistics from an svg path:
-      length (measuring bezier splines as straight lines through the handles).
-      points (all, including duplicates)
-      segments (number of not-connected!) path segments.
-      simple bounding box (ignoring curves of splines, but inclding handles.)
-  """
-  xmin = 1e99
-  ymin = 1e99
-  xmax = -1e99
-  ymax = -1e99
-  p_points = 0
-  p_length = 0
-  p_segments = 0
-
-  path_d = path_d.lower()
-  for p in path_d.split('m'):
-
-    pp = re.sub('[cl,]', ' ', p)
-    pp,closed = re.subn('z\s*$','',pp)
-    xy = pp.split()
-    if len(xy) < 2:
-      # print len(pp)
-      # print "short path error"
-      continue
-    x0 = float(xy[0])
-    y0 = float(xy[1])
-    if x0 > xmax: xmax = x0
-    if x0 < xmin: xmin = x0
-    if y0 > ymax: ymax = y0
-    if y0 < ymin: ymin = y0
-
-    p_points += 1
-    x = xy[2::2]
-    y = xy[3::2]
-    if len(x):
-      p_segments += 1
-      if closed:
-        x.extend(x0)
-        y.extend(y0)
-
-    for i in range(len(x)):
-      p_points += 1
-      dx = float(x[i]) - x0
-      dy = float(y[i]) - y0
-      p_length += math.sqrt( dx * dx + dy * dy )
-      x0,y0 = float(x[i]),float(y[i])
-      if x0 > xmax: xmax = x0
-      if x0 < xmin: xmin = x0
-      if y0 > ymax: ymax = y0
-      if y0 < ymin: ymin = y0
-
-  return { 'points':p_points, 'segments':p_segments, 'length':p_length, 'bbox': (xmin,ymin, xmax, ymax) }
-
-
-def bbox_info(slic3r, file):
-  cmd = [ slic3r, '--no-gui', '--info', file ]
-  p = Popen(cmd, stdout=PIPE, stderr=PIPE)
-  out, err = p.communicate()
-  if len(err):
-    raise ValueError(err)
-
-  bb = {}
-  for l in out.decode().split("\n"):
-    m = re.match('((min|max)_[xyz])\s*=\s*(.*)', l)
-    if m: bb[m.group(1)] = float(m.group(3))
-  if (len(bb) != 6):
-    raise ValueError("slic3r --info did not return 6 elements for bbox")
-  return bb
-
-if args.center != 'false':
-  bb = bbox_info(args.slic3r_cmd, stlfile)
-  # Ouch: bbox info gives us stl coordinates. slic3r translates them into svg px using 75dpi.
-  cx = (-bb['min_x'] + bb['max_x']) * 0.5 * 1/scale * magic * 25.4 / 75
-  cy = (-bb['min_y'] + bb['max_y']) * 0.5 * 1/scale * magic * 25.4 / 75
-# print(cx, cy, file=sys.stderr)
-
-
-try:
-  if args.stdout:
-    tty = open("/dev/tty", "w")
-  else:
-    tty = sys.stderr
-except:
-    tty = sys.stderr
-
-try:
-  proc = subprocess.Popen(cmd, shell=False, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-except OSError as e:
-  raise OSError("{0}\nCommand failed: errno={1} {2}".format(' '.join(cmd), e.errno, e.strerror))
-stdout, stderr = proc.communicate()
-
-if tmpstlfile and os.path.exists(tmpstlfile):
-  os.unlink(tmpstlfile)
-
-if not b'Done.' in stdout:
-  print("Command failed: {0}".format(' '.join(cmd)))
-  print("OUT: " + str(stdout), file=sys.stderr)
-  print("ERR: " + str(stderr), file=sys.stderr)
-  sys.exit(1)
-
-# slic3r produces correct svg files, but with polygons instead of paths, and with undefined strokes.
-# When opened with inkscape, most lines are invisible and polygons cannot be edited.
-# To fix these issues, we postprocess the svg file:
-# * replace polygon nodes with corresponding path nodes.
-# * replace style attribute in polygon nodes with one that has a black stroke
-
-stream = open(svgfile, 'r')
-p = etree.XMLParser(huge_tree=True)
-doc = etree.parse(stream, parser=p)
-stream.close()
-
-doc.getroot().addprevious(etree.Comment(' Imported with '+sys.argv[0]+' V'+_version+" by Juergen Weigert "))
-doc.getroot().attrib['{http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd}docname'] = 'input-stl.svg'
-
-## To change the document units to mm, insert directly after the root node:
-# e.tag = '{http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd}namedview'
-# e.attrib['id'] = "base"
-# e.attrib['{http://www.inkscape.org/namespaces/inkscape}document-units'] = "mm"
-
-layercount = 0
-for e in doc.iterfind('//{*}g'):
-  if e.attrib['{http://slic3r.org/namespaces/slic3r}z'] and e.attrib['id']:
-    e.attrib['{http://www.inkscape.org/namespaces/inkscape}label'] = e.attrib['id'] + ' slic3r:z=' + e.attrib['{http://slic3r.org/namespaces/slic3r}z']
-    del e.attrib['{http://slic3r.org/namespaces/slic3r}z']
-    # for some fun with our inkscape-paths2openscad extension, add sibling to e:
-    # <svg:desc id="descpoly60">Depth: 1mm\nOffset: 31mm</svg:desc>
-    desc = etree.Element('{http://www.w3.org/2000/svg}desc')
-    desc.attrib['id'] = 'descl'+str(layercount)
-    desc.text = "Depth: %.2fmm\nRaise: %.2fmm\n" % (1/scale, layercount/scale)
-    e.append(desc)
-    layercount+=1
-    if args.numbers != 'false':
-      num = etree.Element('{http://www.w3.org/2000/svg}text')
-      num.attrib['id'] = 'textnum'+str(layercount)
-      num.attrib['x'] = str(layercount*2)
-      num.attrib['y'] = str(layercount*4+10)
-      num.attrib['style'] = 'fill:#00FF00;fill-opacity:1;stroke:#00FF00;font-family:FreeSans;font-size:10pt;stroke-opacity:1;stroke-width:0.1'
-      num.text = "%d" % layercount
-      e.append(num)
-    if args.center != 'false':
-      cc = etree.Element('{http://www.w3.org/2000/svg}path')
-      cc.attrib['id'] = 'ccross'+str(layercount)
-      cc.attrib['style'] = 'fill:none;fill-opacity:1;stroke:#0000FF;font-family:FreeSans;font-size:10pt;stroke-opacity:1;stroke-width:0.1'
-      cc.attrib['d'] = 'M %s,%s v 10 M %s,%s h 10 M %s,%s h 4' % (cx, cy-5,  cx-5, cy,  cx-2, cy+5)
-      e.append(cc)
-
-
-
-polygoncount = 0
-for e in doc.iterfind('//{*}polygon'):
-  # e.tag = '{http://www.w3.org/2000/svg}polygon'
-  # e.attrib = {'{http://slic3r.org/namespaces/slic3r}type': 'contour', 'points': '276.422496,309.4 260.209984,309.4 260.209984,209.03 276.422496,209.03', 'style': 'fill: white'}
-  e.tag = re.sub('polygon$', 'path', e.tag)
-  polygoncount += 1
-  e.attrib['id'] = 'polygon%d' % polygoncount
-  e.attrib['{http://www.inkscape.org/namespaces/inkscape}connector-curvature'] = '0'
-  e.attrib['style'] = 'fill:none;fill-opacity:1;stroke:#FF0000;stroke-opacity:1;stroke-width:0.1'
-  e.attrib['d'] = 'M ' + re.sub(' ', ' L ', scale_points(e.attrib['points'], 1/scale)) + ' Z'
-  del e.attrib['points']
-  if e.attrib.get('{http://slic3r.org/namespaces/slic3r}type') == 'contour':
-    # remove contour, but keep all slic3r:type='hole', whatever it is worth later.
-    del e.attrib['{http://slic3r.org/namespaces/slic3r}type']
-
-try:
-  # Available in lxml since 3.5.0
-  # Make an xmlns declaration in the svg header, and use the "inkscape:" prefix throughout the document.
-  etree.cleanup_namespaces(doc.getroot(), top_nsmap={
-    'inkscape': 'http://www.inkscape.org/namespaces/inkscape',
-    'sodipodi': 'http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd'})
-except:
-  pass
-
-try:
-  print("{0}: {1} polygons in {2} layers converted to paths.".format(svgfile, polygoncount, layercount), file=tty)
-except:
-  pass
-
-if args.stdout:
-  doc.write(sys.stdout.buffer)
-else:
-  doc.write(svgfile, pretty_print=True)