loop closing with snap implemented.

No workaround for buggy cubicsuperpath.formatPath() found.

chain_paths.inx

@@ -14,10 +14,11 @@
 	<option value="pt">pt</option>
 	<option value="px">px</option></param>
   <param name="snap" type="boolean" _gui-text="Snap connecting ends together">false</param>
+  <param name="close" type="boolean" _gui-text="Close loops (start/end of the same path)">true</param>
   <!-- Keep in sync with chain_paths.py line 19 __version__ = ... -->
   <param name="about_version" type="description">
-  
-  
+
+
   https://github.com/fablabnbg/inkscape-chain-paths
   Version 0.6</param>
 

chain_paths.py

@@ -18,22 +18,27 @@
 # 2015-11-26 jw, V0.5 -- HACK to resolve some self-reversing path segments.
 #        https://github.com/fablabnbg/inkscape-chain-paths/issues/1
 # 2020-04-10 jw, V0.6 -- Close paths correctly. Self reversing path hack was too eager.
+#        Workaround for cubicsuperpath.parsePath/formatPath limitation.
+#        Started python3 compatibility.
+
+from __future__ import print_function
 
 __version__ = '0.6'        # Keep in sync with chain_paths.inx ca line 22
-__author__ = 'Juergen Weigert <juewei@fabmail.org>'
+__author__ = 'Juergen Weigert <juergen@fabmail.org>'
 
 import sys, os, shutil, time, logging, tempfile, math
+import re
 
-debug = True
-#debug = False
+#debug = True
+debug = False
 
 # search path, so that inkscape libraries are found when we are standalone.
 sys_platform = sys.platform.lower()
 if sys_platform.startswith('win'):        # windows
   sys.path.append('C:\Program Files\Inkscape\share\extensions')
-elif sys_platform.startswith('darwin'):        # mac
+elif sys_platform.startswith('darwin'):   # mac
   sys.path.append('/Applications/Inkscape.app/Contents/Resources/extensions')
-else:                                   # linux
+else:                                     # linux
   # if sys_platform.startswith('linux'):
   sys.path.append('/usr/share/inkscape/extensions')
 
@@ -64,6 +69,7 @@ def __init__(self):
     # as establishing a transform from the viewbox to the display.
     self.chain_epsilon = 0.01
     self.snap_ends = True
+    self.close_loops = True
     self.segments_done = {}
     self.min_missed_distance_sq = None
     self.chained_count = 0
@@ -75,18 +81,18 @@ def __init__(self):
         self.tty = open("CON:", 'w')        # windows. Does this work???
       except:
         self.tty = open(os.devnull, 'w')  # '/dev/null' for POSIX, 'nul' for Windows.
-    if debug: print >>self.tty, "__init__"
+    if debug: print("__init__", file=self.tty)
 
     self.OptionParser.add_option('-V', '--version',
           action = 'store_const', const=True, dest='version', default=False,
           help = 'Just print version number ("' + __version__ + '") and exit.')
     self.OptionParser.add_option('-s', '--snap', action='store', dest='snap_ends', type='inkbool', default=True, help='snap end-points together when connecting')
+    self.OptionParser.add_option('-c', '--close', action='store', dest='close_loops', type='inkbool', default=True, help='close loops (start/end of the same path)')
     self.OptionParser.add_option('-u', '--units', action='store', dest="units", type="string", default="mm", help="measurement unit for epsilon")
     self.OptionParser.add_option('-e', '--epsilon', action='store',
           type='float', dest='chain_epsilon', default=0.01, help="Max. distance to connect [mm]")
 
   def version(self):
-    print "hiuhu"
     return __version__
   def author(self):
     return __author__
@@ -113,7 +119,7 @@ def set_segment_done(self, id, n, msg=''):
     if not id in self.segments_done:
       self.segments_done[id] = {}
     self.segments_done[id][n] = True
-    if debug: print >>self.tty, "done", id, n, msg
+    if debug: print("done", id, n, msg, file=self.tty)
 
   def is_segment_done(self, id, n):
     if not id in self.segments_done:
@@ -157,12 +163,13 @@ def near_ends(self, end1, end2):
 
   def effect(self):
     if self.options.version:
-      print __version__
+      print(__version__)
       sys.exit(0)
 
     self.calc_unit_factor(self.options.units)
 
     if self.options.snap_ends     is not None: self.snap_ends     = self.options.snap_ends
+    if self.options.close_loops   is not None: self.close_loops   = self.options.close_loops
     if self.options.chain_epsilon is not None: self.chain_epsilon = self.options.chain_epsilon
     if self.chain_epsilon < 0.001: self.chain_epsilon = 0.001        # keep a minimum.
     self.eps_sq = self.chain_epsilon * self.unit_factor * self.chain_epsilon * self.unit_factor
@@ -176,7 +183,7 @@ def effect(self):
       if node.tag != inkex.addNS('path', 'svg'):
         inkex.errormsg(_("Object " + id + " is not a path. Try\n  - Path->Object to Path\n  - Object->Ungroup"))
         return
-      if debug: print >>self.tty, "id=" + str(id), "tag=" + str(node.tag)
+      if debug: print("id=" + str(id), "tag=" + str(node.tag), file=self.tty)
       path_d = cubicsuperpath.parsePath(node.get('d'))
       sub_idx = -1
       for sub in path_d:
@@ -186,29 +193,31 @@ def effect(self):
         # [[handle0_OUT, point0, handle0_1], [handle1_0, point1, handle1_2], [handle2_1, point2, handle2_OUT]]
         # the _OUT handles at the end of the path are ignored. The data structure has them identical to their points.
         #
-        if debug: print >>self.tty, "   sub=" + str(sub)
+        if debug: print("   sub=" + str(sub), file=self.tty)
         end1 = [sub[ 0][1][0], sub[ 0][1][1]]
         end2 = [sub[-1][1][0], sub[-1][1][1]]
 
-        # Removes self revesals when building candidate segments list.
+        # Remove trivial self revesal when building candidate segments list.
         if ((len(sub) == 3) and self.near_ends(end1, end2)):
-          if debug: print >>self.tty, "dropping segment from self-reversing path, length:", len(sub)
+          if debug: print("dropping segment from self-reversing path, length:", len(sub), file=self.tty)
           sub.pop()
           end2 = [sub[-1][1][0], sub[-1][1][1]]
 
         segments.append({'id': id, 'n': sub_idx, 'end1': end1, 'end2':end2, 'seg': sub})
       if node.get(inkex.addNS('type', 'sodipodi')):
         del node.attrib[inkex.addNS('type', 'sodipodi')]
-    if debug: print >>self.tty, "-------- seen:"
+    if debug: print("-------- seen:", file=self.tty)
     for s in segments:
-      if debug: print >>self.tty, s['id'], s['n'], s['end1'], s['end2']
+      if debug: print(s['id'], s['n'], s['end1'], s['end2'], file=self.tty)
 
     # chain the segments
     obsoleted = 0
     remaining = 0
     for id, node in self.selected.iteritems():
       # path_style = simplestyle.parseStyle(node.get('style'))
       path_d = cubicsuperpath.parsePath(node.get('d'))
+      # ATTENTION: for parsePath() it is the same, if first and last point coincide, or if the path is really closed.
+      path_closed = True if re.search("z\s*$", node.get('d')) else False
       new = []
       cur_idx = -1
       for chain in path_d:
@@ -225,7 +234,7 @@ def effect(self):
           end1 = [chain[ 0][1][0], chain[ 0][1][1]]
           end2 = [chain[-1][1][0], chain[-1][1][1]]
 
-          # Removes self revesals when doing the actual chain operations.
+          # Remove trivial self revesal when doing the actual chain operation.
           if ((len(chain) == 3) and self.near_ends(end1, end2)):
             chain.pop()
             end2 = [chain[-1][1][0], chain[-1][1][1]]
@@ -241,7 +250,7 @@ def effect(self):
                 self.near_ends(end2, seg['end2'])):
               seg['seg'] = self.reverse_segment(seg['seg'])
               seg['end1'], seg['end2'] = seg['end2'], seg['end1']
-              if debug: print >>self.tty, "reversed seg", seg['id'], seg['n']
+              if debug: print("reversed seg", seg['id'], seg['n'], file=self.tty)
 
             if self.near_ends(end1, seg['end2']):
               # prepend seg to chain
@@ -265,22 +274,45 @@ def effect(self):
           # Finally, we can check, if the resulting path is a closed path:
           # Closing a path here, isolates it from the rest.
           # But as we prefer to make the chain as long as possible, we close late.
+          if self.near_ends(end1, end2) and not path_closed and self.close_loops:
+              if debug: print("closing closeable loop", id, file=self.tty)
+              if self.snap_ends:
+                  # move first point to mid position
+                  x1n = (chain[0][1][0] + chain[-1][1][0]) * 0.5
+                  y1n = (chain[0][1][1] + chain[-1][1][1]) * 0.5
+                  chain[0][1][0], chain[0][1][1] = x1n, y1n
+                  # merge handle of the last point to the handle of the first point
+                  dx0e = chain[-1][0][0] - chain[-1][1][0]
+                  dy0e = chain[-1][0][1] - chain[-1][1][1]
+                  if debug: print("handle diff: ", dx0e, dy0e, file=self.tty)
+                  # FIXME: this does not work. cubicsuperpath.formatPath() ignores this handle.
+                  chain[0][0][0], chain[0][0][1] = x1n+dx0e, y1n+dy0e
+                  # drop last point
+                  chain.pop()
+                  end2 = [chain[-1][1][0], chain[-1][1][1]]
+              path_closed = True
+              self.chained_count +=1
+
           new.append(chain)
 
       if not len(new):
         # node.clear()
         node.getparent().remove(node)
         obsoleted += 1
-        if debug: print >>self.tty, "Path node obsoleted:", id
+        if debug: print("Path node obsoleted:", id, file=self.tty)
       else:
         remaining += 1
-        node.set('d', cubicsuperpath.formatPath(new))
+        # BUG: All previously closed loops, are open, after we convert them back with cubicsuperpath.formatPath()
+        p_fmt = cubicsuperpath.formatPath(new)
+        if path_closed: p_fmt += " z"
+        if debug: print("new path :", p_fmt, file=self.tty)
+        node.set('d', p_fmt)
 
     # statistics:
-    print >>self.tty, "Path nodes obsoleted:", obsoleted, "\nPath nodes remaining:", remaining
+    if debug: print("Path nodes obsoleted:", obsoleted, "\nPath nodes remaining:", remaining, file=self.tty)
     if self.min_missed_distance_sq is not None:
-      print >>self.tty, "min_missed_distance:", math.sqrt(float(self.min_missed_distance_sq))/self.unit_factor, '>', self.chain_epsilon, self.options.units
-    print >>self.tty, "Successful link operations: ", self.chained_count
+      if debug: print("min_missed_distance:", math.sqrt(float(self.min_missed_distance_sq))/self.unit_factor, '>', self.chain_epsilon, self.options.units, file=self.tty)
+    if debug: print("Successful link operations: ", self.chained_count, file=self.tty)
 
 if __name__ == '__main__':
         e = ChainPaths()

setup.py

@@ -1,9 +1,11 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
-# 
+#
 # sudo zypper in python-setuptools
 # http://docs.python.org/2/distutils/setupscript.html#installing-additional-files
 #
+
+from __future__ import print_function
 import sys,os,glob,re
 
 from distutils.core import setup
@@ -13,7 +15,7 @@
 e = chain_paths.ChainPaths()
 m = re.match('(.*)\s+<(.*)>', e.author())
 
-# print ('.',['Makefile'] + glob.glob('chain_paths*'))
+# print('.',['Makefile'] + glob.glob('chain_paths*'))
 
 class PyTest(TestCommand):
     def finalize_options(self):
@@ -49,5 +51,5 @@ def run_tests(self):
       long_description="".join(open('README.md').readlines()),
       # tests_require=['pytest', 'scipy'],
       #packages=['pyPdf','reportlab.pdfgen','reportlab.lib.colors','pygame.font' ],
-# 
+#
 )