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Diffstat (limited to 'share/extensions/path_envelope.py')
| -rwxr-xr-x | share/extensions/path_envelope.py | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/share/extensions/path_envelope.py b/share/extensions/path_envelope.py new file mode 100755 index 0000000..3fc263e --- /dev/null +++ b/share/extensions/path_envelope.py @@ -0,0 +1,159 @@ +# coding=utf-8 +# +# Copyright (C) 2005 Aaron Spike, aaron@ekips.org +# +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 2 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program; if not, write to the Free Software +# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. +# + +import inkex +from inkex.transforms import DirectedLineSegment +from inkex.localization import inkex_gettext as _ +from operator import truediv + + +class Envelope(inkex.EffectExtension): + """Distort a path/group of paths to a second path""" + + def effect(self): + if len(self.svg.selection) != 2: + raise inkex.AbortExtension(_("You must select two objects only.")) + + obj, envelope = self.svg.selection + + if isinstance(obj, (inkex.PathElement, inkex.Group)): + if isinstance(envelope, inkex.PathElement): + # Get bounding box plus any extra composed transform of parents. + bbox = obj.bounding_box(obj.getparent().composed_transform()) + + # distill trafo into four node points + path = envelope.path.transform( + envelope.composed_transform() + ).to_superpath() + tbox = self.envelope_box_from_path(path) + else: + if isinstance(envelope, inkex.Group): + raise inkex.AbortExtension( + _( + "The second selected object is a group, not a" + " path.\nTry using Object->Ungroup." + ) + ) + raise inkex.AbortExtension( + _( + "The second selected object is not a path.\nTry using" + " the procedure Path->Object to Path." + ) + ) + else: + raise inkex.AbortExtension( + _( + "The first selected object is neither a path nor a group.\nTry using" + " the procedure Path->Object to Path." + ) + ) + + self.process_object(obj, tbox, bbox) + + def envelope_box_from_path(self, envelope_path): + if len(envelope_path) < 1 or len(envelope_path[0]) < 4: + raise inkex.AbortExtension( + _("Second selected path is too short. Must be four or more nodes.") + ) + trafo = [[(csp[1][0], csp[1][1]) for csp in subs] for subs in envelope_path][0][ + :4 + ] + # vectors pointing away from the trafo origin + tbox = [ + DirectedLineSegment(trafo[0], trafo[1]), + DirectedLineSegment(trafo[1], trafo[2]), + DirectedLineSegment(trafo[3], trafo[2]), + DirectedLineSegment(trafo[0], trafo[3]), + ] + vects = [segment.vector for segment in tbox] + if ( + 0.0 + == vects[0].cross(vects[1]) + == vects[1].cross(vects[2]) + == vects[2].cross(vects[3]) + ): + raise inkex.AbortExtension( + _("The points for the selected envelope must not all be in a line.") + ) + return tbox + + def process_object(self, obj, tbox, bbox): + if isinstance(obj, inkex.PathElement): + self.process_path(obj, tbox, bbox) + elif isinstance(obj, inkex.Group): + self.process_group(obj, tbox, bbox) + + def process_group(self, group, tbox, bbox): + """Go through all groups to process all paths inside them""" + for node in group: + self.process_object(node, tbox, bbox) + + def process_path(self, element, tbox, bbox): + # Get out path's absolute and root coordinates, so obj and envelope + # are always in the same coordinate system. + points = ( + element.path.to_absolute() + .transform(element.composed_transform()) + .to_superpath() + ) + + for subs in points: + for csp in subs: + csp[0] = self.transform_point(tbox, bbox, *csp[0]) + csp[1] = self.transform_point(tbox, bbox, *csp[1]) + csp[2] = self.transform_point(tbox, bbox, *csp[2]) + + # Put the modified path back, undo the root transformation + element.path = points.to_path().transform(-element.composed_transform()) + + @staticmethod + def transform_point(tbox, bbox, x, y): + """Transform algorithm thanks to Jose Hevia (freon)""" + vector = (x, y) - bbox.minimum + xratio, yratio = map(truediv, vector, (bbox.width, bbox.height)) + horz = DirectedLineSegment( + tbox[0].point_at_ratio(xratio), tbox[2].point_at_ratio(xratio) + ) + vert = DirectedLineSegment( + tbox[3].point_at_ratio(yratio), tbox[1].point_at_ratio(yratio) + ) + denom = horz.vector.cross(vert.vector) + if denom == 0.0: + # Degenerate cases of intersecting envelope edges + if horz.length == 0.0: + return horz.start + if vert.length == 0.0: + return vert.start + # Here we should know that the lines share a start or end point. + if horz.vector.dot(vert.vector) < 0: + # Segments point opposite directions + if (horz.start - vert.start).length <= 1e-8: + return horz.start + return horz.end + # Otherwise they are pointing the same direction + if (horz.start - vert.end).length < 1e-8: + return horz.start + return horz.end + # If we didn't hit a degenerate case we can treat the segments as infinite lines + intersect_ratio = (vert.start - horz.start).cross(vert.vector) / denom + return horz.point_at_ratio(intersect_ratio) + + +if __name__ == "__main__": + Envelope().run() |