Added "Snap Object Points"
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extensions/fablabchemnitz/snap_objects.inx
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21
extensions/fablabchemnitz/snap_objects.inx
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<?xml version="1.0" encoding="UTF-8"?>
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<inkscape-extension xmlns="http://www.inkscape.org/namespace/inkscape/extension">
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<name>Snap Object Points</name>
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<id>fablabchemnitz.de.snap_objects</id>
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<param name="max_dist" type="float" min="1" max="9999" precision="2" gui-text="Maximum snap distance">25</param>
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<param name="controls" type="bool" gui-text="Snap control points">true</param>
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<param name="ends" type="bool" gui-text="Snap endpoints">true</param>
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<param name="first_only" type="bool" gui-text="Modify only the first selected path">false</param>
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<label>This effect snaps points in each selected object to nearby points in other selected objects.</label>
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<effect>
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<object-type>path</object-type>
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<effects-menu>
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<submenu name="FabLab Chemnitz">
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<submenu name="Modify existing Path(s)"/>
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</submenu>
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</effects-menu>
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</effect>
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<script>
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<command location="inx" interpreter="python">snap_objects.py</command>
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</script>
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</inkscape-extension>
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137
extensions/fablabchemnitz/snap_objects.py
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137
extensions/fablabchemnitz/snap_objects.py
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#!/usr/bin/env python3
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'''
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Copyright (C) 2020 Scott Pakin, scott-ink@pakin.org
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301, USA.
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'''
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from collections import defaultdict
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import inkex
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from inkex.paths import Arc, Curve, Horz, Line, Move, Quadratic, Smooth, TepidQuadratic, Vert, ZoneClose
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class SnapObjects(inkex.Effect):
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"Snap the points on multiple paths towards each other."
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def __init__(self):
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inkex.Effect.__init__(self)
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self.arg_parser.add_argument('--max_dist', type=float, default=25.0, help='Maximum distance to be considered a "nearby" point')
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self.arg_parser.add_argument('--controls', type=inkex.Boolean, default=True, help='Snap control points')
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self.arg_parser.add_argument('--ends', type=inkex.Boolean, default=True, help='Snap endpoints')
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self.arg_parser.add_argument('--first_only', type=inkex.Boolean, default=True, help='Modify only the first selected path')
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def _bin_points(self):
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"Associate each path ID with a list of control points and a list of endpoints."
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cpoints = defaultdict(list)
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epoints = defaultdict(list)
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for node in self.svg.selection.filter(inkex.PathElement).values():
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for cmd in node.path.to_absolute().proxy_iterator():
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pid = node.get_id()
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cpoints[pid].extend(cmd.control_points)
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epoints[pid].append(cmd.end_point)
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return cpoints, epoints
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def _find_nearest(self, pid, x0, y0, other_points):
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'''Find the nearest neighbor to a given point, and return the midpoint
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of the given point and its neighbor.'''
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max_dist2 = self.options.max_dist**2 # Work with squares instead of wasting time on square roots.
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bx, by = x0, y0 # Best new point
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best_dist2 = max_dist2 # Minimal distance observed from (x0, y0)
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for k, pts in other_points.items():
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if k == pid:
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continue # Don't compare to our own points.
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for vec in pts:
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x1, y1 = vec.x, vec.y
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dist2 = (x1 - x0)**2 + (y1 - y0)**2 # Squared distance
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if dist2 > best_dist2:
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continue # Not the nearest point
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best_dist2 = dist2
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bx, by = x1, y1
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return (x0 + bx)/2, (y0 + by)/2
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def _simplify_paths(self):
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'Make all commands absolute, and replace Vert and Horz commands with Line.'
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for node in self.svg.selection.filter(inkex.PathElement).values():
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path = node.path.to_absolute()
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new_path = []
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prev = inkex.Vector2d()
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prev_prev = inkex.Vector2d()
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first = inkex.Vector2d()
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for i, cmd in enumerate(path):
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if i == 0:
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first = cmd.end_point(first, prev)
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prev, prev_prev = first, first
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if isinstance(cmd, Vert):
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cmd = cmd.to_line(prev)
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elif isinstance(cmd, Horz):
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cmd = cmd.to_line(prev)
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new_path.append(cmd)
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if isinstance(cmd, (Curve, Quadratic, Smooth, TepidQuadratic)):
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prev_prev = list(cmd.control_points(first, prev, prev_prev))[-2]
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prev = cmd.end_point(first, prev)
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node.path = new_path
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def effect(self):
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"""Snap control points to other objects' control points and endpoints
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to other objects' endpoints."""
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# This function uses an O(n^2) algorithm, which shouldn't be too slow
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# for typical point counts.
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#
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# As a preprocessing step, we first simplify the paths to reduce the
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# number of special cases we'll need to deal with. Then, we associate
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# each path with all of its control points and endpoints.
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if len(self.svg.selection.filter(inkex.PathElement)) < 2:
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raise inkex.utils.AbortExtension(_('Snap Object Points requires that at least two paths be selected.'))
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self._simplify_paths()
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cpoints, epoints = self._bin_points()
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# Process in turn each command on each path.
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for node in self.svg.selection.filter(inkex.PathElement).values():
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pid = node.get_id()
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path = node.path
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new_path = []
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for cmd in path:
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args = cmd.args
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new_args = list(args)
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na = len(args)
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if isinstance(cmd, (Curve, Line, Move, Quadratic, Smooth, TepidQuadratic)):
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# Zero or more control points followed by an endpoint.
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if self.options.controls:
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for i in range(0, na - 2, 2):
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new_args[i], new_args[i + 1] = self._find_nearest(pid, args[i], args[i + 1], cpoints)
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if self.options.ends:
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new_args[na - 2], new_args[na - 1] = self._find_nearest(pid, args[na - 2], args[na - 1], epoints)
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elif isinstance(cmd, ZoneClose):
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# No arguments at all.
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pass
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elif isinstance(cmd, Arc):
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# Non-coordinates followed by an endpoint.
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if self.options.ends:
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new_args[na - 2], new_args[na - 1] = self._find_nearest(pid, args[na - 2], args[na - 1], epoints)
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else:
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# Unexpected command.
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inkex.errormsg(_('Unexpected path command "%s"' % cmd.name))
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new_path.append(cmd.__class__(*new_args))
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node.path = new_path
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if self.options.first_only:
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break
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if __name__ == '__main__':
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SnapObjects().run()
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