mightyscape-1.2/extensions/fablabchemnitz/chain_paths/chain_paths.py

#!/usr/bin/env python3
#
# Inkscape extension making long continuous paths from shorter pieces.
# (C) 2015 juewei@fabmail.org
#
# code snippets visited to learn the extension 'effect' interface:
# - convert2dashes.py
# - http://github.com/jnweiger/inkscape-silhouette
# - http://github.com/jnweiger/inkscape-gears-dev
# - http://sourceforge.net/projects/inkcut/
# - http://code.google.com/p/inkscape2tikz/
# - http://code.google.com/p/eggbotcode/
#
# 2015-11-15 jw, V0.1 -- initial draught
# 2015-11-16 jw, V0.2 -- fixed endpoints after chaining.
# 2015-11-16 jw, V0.3 -- all possible chains connected. Yeah
# 2015-11-16 jw, V0.4 -- gui fully functional.
# 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.
# 2020-05-27 vi, V0.7 -- Upgrade to Inkscape 1.0. Write debug info to inkex debug dialog.

from __future__ import print_function

__version__ = '0.7'        # Keep in sync with chain_paths.inx ca line 22
__author__ = 'Juergen Weigert <juergen@fabmail.org>'
__credits__ = ['Juergen Weigert', 'Veronika Irvine']

import sys
import math
import re
import inkex
from inkex.paths import CubicSuperPath, Path
from optparse import SUPPRESS_HELP

class ChainPaths(inkex.EffectExtension):

    def __init__(self):
        inkex.Effect.__init__(self)

        # For handling an SVG viewbox attribute, we will need to know the
        # values of the document's <svg> width and height attributes as well
        # 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

        self.arg_parser.add_argument('-V', '--version', type=inkex.Boolean, default=False, help = 'Just print version number ("' + __version__ + '") and exit.')
        self.arg_parser.add_argument('-s', '--snap_ends', type=inkex.Boolean, default=True, help='snap end-points together when connecting')
        self.arg_parser.add_argument('-c', '--close_loops', type=inkex.Boolean, default=True, help='close loops (start/end of the same path)')
        self.arg_parser.add_argument('-l', '--limit', type=int, default=2000, help='Maximum items to process')
        self.arg_parser.add_argument('-u', '--units', default="mm", help="measurement unit for epsilon")
        self.arg_parser.add_argument('-e', '--chain_epsilon', type=float, default=0.01, help="Max. distance to connect [mm]")
        self.arg_parser.add_argument('-d', '--debug', type=inkex.Boolean, default=False, help='Debug')

    def version(self):
        return __version__
    def author(self):
        return __author__

    def calc_unit_factor(self, units='mm'):
                """ return the scale factor for all dimension conversions.
                        - The document units are always irrelevant as
                            everything in inkscape is expected to be in 90dpi pixel units
                """
                dialog_units = self.svg.unittouu(str(1.0)+units)
                self.unit_factor = 1.0 / dialog_units
                return self.unit_factor

    def reverse_segment(self, seg):
        r = []
        for s in reversed(seg):
            # s has 3 elements: handle1, point, handle2
            # Swap handles.
            s.reverse()
            r.append(s)
        return r

    def set_segment_done(self, so, id, n, msg=''):
        if not id in self.segments_done:
            self.segments_done[id] = {}
        self.segments_done[id][n] = True
        if so.debug: inkex.utils.debug("done {} {} {}".format(id, n, msg))

    def is_segment_done(self, id, n):
        if not id in self.segments_done:
            return False
        if n in self.segments_done[id]:
            return True
        return False

    def link_segments(self, seg1, seg2):
        if self.snap_ends:
            seg = seg1[:-1]
            p1 = seg1[-1]
            p2 = seg2[0]
            # fuse p1 and p2 to create one new point:
            # first handle from p1, point coordinates averaged, second handle from p2
            seg.append([
                        [ p1[0][0]                 ,  p1[0][1]                 ],
                        [(p1[1][0] + p2[1][0]) * .5, (p1[1][1] + p2[1][1]) * .5],
                        [ p2[2][0]                 ,  p2[2][1]                 ]
                        ])
            seg.extend(seg2[1:])
        else:
            seg = seg1[:]
            seg.extend(seg2[:])
        self.chained_count += 1
        return seg

    def near_ends(self, end1, end2):
        """ requires self.eps_sq to be the square of the near distance """
        dx = end1[0] - end2[0]
        dy = end1[1] - end2[1]
        d_sq = dx * dx + dy * dy
        if d_sq > self.eps_sq:
            if self.min_missed_distance_sq is None:
                self.min_missed_distance_sq = d_sq
            elif self.min_missed_distance_sq > d_sq:
                self.min_missed_distance_sq = d_sq
            return False
        else:
            return True

    def effect(self):
        so = self.options

        if so.version:
            print(__version__)
            sys.exit(0)

        self.calc_unit_factor(so.units)

        if so.snap_ends     is not None: self.snap_ends     = so.snap_ends
        if so.close_loops   is not None: self.close_loops   = so.close_loops
        if so.chain_epsilon is not None: self.chain_epsilon = so.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

        selected = self.svg.selected.items()

        itemsCount = len(selected)
        if not itemsCount:
            inkex.errormsg("Please select one or more objects.")
            return

        #selected = dict(reversed(list(selected))) #reverse
        if so.limit > 0 and itemsCount > so.limit:
            inkex.utils.debug("Maximum items to process is set to {}. You selected {} items. We continue with processing until limit is reached.".format(so.limit, itemsCount))

        segments = []
        workedon = 0
        for id, node in selected:
            if node.tag != inkex.addNS('path', 'svg'):
                inkex.errormsg("Object id {} is not a path. Try\n  - Path->Object to Path\n  - Object->Ungroup".format(node.get('id')))
                return
            #check if node has a transform. If yes, print a warning
            if node.get('transform') is not None:
                inkex.utils.debug("Warning: node {} has transform {}. Use 'Apply Transforms' extension before to handle this.".format(node.get('id'), node.get('transform')))
                return
            
            if so.debug: inkex.utils.debug("id={}, tag=".format(node.get('id'), node.tag))
            path_d = CubicSuperPath(Path(node.get('d')))
            sub_idx = -1
            for sub in path_d:
                sub_idx += 1
                # sub = [[[200.0, 300.0], [200.0, 300.0], [175.0, 290.0]], [[175.0, 265.0], [220.37694, 256.99876], [175.0, 240.0]], [[175.0, 215.0], [200.0, 200.0], [200.0, 200.0]]]
                # this is a path of three points. All the bezier handles are included. the Structure is:
                # [[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 so.debug: inkex.utils.debug("   sub={}".format(sub))
                end1 = [sub[ 0][1][0], sub[ 0][1][1]]
                end2 = [sub[-1][1][0], sub[-1][1][1]]

                # Remove trivial self reversal when building candidate segments list.
                if ((len(sub) == 3) and self.near_ends(end1, end2)):
                    if so.debug: inkex.utils.debug("dropping segment from self-reversing path, length: {}".format(len(sub)))
                    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')]
            workedon += 1
            if workedon >= so.limit and so.limit > 0:
                    break

        if so.debug: inkex.utils.debug("-------- seen: ")
        for s in segments:
            if so.debug: inkex.utils.debug("{}, {}, {}, {}".format(s['id'], s['n'], s['end1'], s['end2']))

        # chain the segments
        obsoleted = 0
        remaining = 0

        workedon = 0
        for id, node in selected:
            path_d = CubicSuperPath(Path(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(r'z\s*$', node.get('d')) else False
            new = []
            cur_idx = -1
            for chain in path_d:
                cur_idx += 1
                if not self.is_segment_done(id, cur_idx):
                    # quadratic algorithm: we check both ends of the current segment.
                    # If one of them is near another known end from the segments list, we
                    # chain this segment to the current segment and remove it from the
                    # list,
                    # end1-end1 or end2-end2: The new segment is reversed.
                    # end1-end2: The new segment is prepended to the current segment.
                    # end2-end1: The new segment is appended to the current segment.
                    self.set_segment_done(so, id, cur_idx, "output") # do not cross with ourselves.
                    end1 = [chain[ 0][1][0], chain[ 0][1][1]]
                    end2 = [chain[-1][1][0], chain[-1][1][1]]

                    # 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]]

                    segments_idx = 0
                    while segments_idx < len(segments):
                        seg = segments[segments_idx]
                        if self.is_segment_done(seg['id'], seg['n']):
                            segments_idx += 1
                            continue

                        if (self.near_ends(end1, seg['end1']) or
                                self.near_ends(end2, seg['end2'])):
                            seg['seg'] = self.reverse_segment(seg['seg'])
                            seg['end1'], seg['end2'] = seg['end2'], seg['end1']
                            if so.debug: inkex.utils.debug("reversed seg {}, {}".format(seg['id'], seg['n']))

                        if self.near_ends(end1, seg['end2']):
                            # prepend seg to chain
                            self.set_segment_done(so, seg['id'], seg['n'], 'prepended to {} {}'.format(id, cur_idx))
                            chain = self.link_segments(seg['seg'], chain)
                            end1 = [chain[0][1][0], chain[0][1][1]]
                            segments_idx = 0 # this chain changed. re-visit all candidate
                            continue

                        if self.near_ends(end2, seg['end1']):
                            # append seg to chain
                            self.set_segment_done(so, seg['id'], seg['n'], 'appended to {} {}'.format(id, cur_idx))
                            chain = self.link_segments(chain, seg['seg'])
                            end2 = [chain[-1][1][0], chain[-1][1][1]]
                            segments_idx = 0 # this chain changed. re-visit all candidate
                            continue

                        segments_idx += 1

                    # Now all joinable segments are joined.
                    # 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 so.debug: inkex.utils.debug("closing closeable loop {}".format(id))
                            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 so.debug: inkex.utils.debug("handle diff: {} {}".format(dx0e, dy0e))
                                    # 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()
                if node.getparent() is not None:
                        node.delete()
                        obsoleted += 1
                        if so.debug: inkex.utils.debug("Path node obsoleted: {}".format(id))
            else:
                remaining += 1
                # BUG: All previously closed loops are open after we convert them back with cubicsuperpath.formatPath()
                p_fmt = str(Path(CubicSuperPath(new).to_path().to_arrays()))
                if path_closed: p_fmt += " z"
                if so.debug: inkex.utils.debug("new path: {}".format(p_fmt))
                node.set('d', p_fmt)
            workedon += 1
            if workedon >= so.limit and so.limit > 0:
                     break

        # statistics:
        if so.debug: inkex.utils.debug("Path nodes obsoleted: {}\nPath nodes remaining: {}".format(obsoleted, remaining))
        if self.min_missed_distance_sq is not None:
            if so.debug: inkex.utils.debug("min_missed_distance: {} > {}".format(math.sqrt(float(self.min_missed_distance_sq))/self.unit_factor, self.chain_epsilon)+str(so.units))
        if so.debug: inkex.utils.debug("Successful link operations: {}".format(self.chained_count))

if __name__ == '__main__':
        ChainPaths().run()