added wrapper shell script; moved import inkex after path setting, improved an error message

centerline-trace.py

@@ -47,7 +47,6 @@ __version__ = '0.2'	# Keep in sync with chain_paths.inx ca line 22
 __author__ = 'Juergen Weigert <juewei@fabmail.org>'
 
 import sys, os, re, math, tempfile, subprocess, base64
-import inkex, simplestyle
 
 try:
   from PIL import Image
@@ -72,7 +71,7 @@ else:   				# linux
   sys.path.append('/usr/share/inkscape/extensions')
 
 # inkscape libraries
-import inkex
+import inkex, simplestyle
 import cubicsuperpath
 
 inkex.localize()
@@ -257,7 +256,7 @@ class TraceCenterline(inkex.Effect):
     for id, node in self.selected.iteritems():
       if debug: print >>self.tty, "id="+str(id), "tag="+str(node.tag)
       if node.tag != inkex.addNS('image','svg'):
-        inkex.errormsg(_("Object "+id+" is not an image. Try\n  - Object->Ungroup"))
+        inkex.errormsg(_("Object "+id+" is not an image. seen:"+str(node.tag)+" expected:"+inkex.addNS('image','svg')+"\n Try - Object->Ungroup"))
         return
       # handle two cases. Embedded and linked images
       # <image .. xlink:href="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAT8AA ..." preserveAspectRatio="none" height="432" width="425" transform="matrix(1,0,-0.52013328,0.85408511,0,0)"/>

centerline-trace.sh

+#!/bin/sh
+# shell script wrapper to run an inkscape extension 
+# as a standaloine tool
+
+image=$1 
+test -z "$image" && image=./testdata/kringel.png
+tmpsvg=/tmp/$$-centerline-trace-wrapper.svg
+
+cat << EOF > $tmpsvg
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   xmlns:xlink="http://www.w3.org/1999/xlink"
+   width="210mm"
+   height="297mm"
+   viewBox="0 0 210 297">
+  <g
+     inkscape:label="Ebene 1"
+     inkscape:groupmode="layer"
+     id="layer1">
+    <image
+       sodipodi:absref="$image"
+       xlink:href="$image"
+       width="1456.2667"
+       height="819.15002"
+       preserveAspectRatio="none"
+       id="image4421"
+       x="-577.12152"
+       y="-226.81631" />
+  </g>
+</svg>
+EOF
+
+python centerline-trace.py --id=image4421 $tmpsvg
+#rm $tmpsvg