inkscape/share/extensions/long_shadow.py

#!/usr/bin/env python3
# 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.
#
"""Adds a "drop shadow" to any selected number of path objects. Optionally, the stroke
color can be used for the shadow"""

import math

import inkex
from inkex.paths import (
    Move,
    Line,
    Curve,
    ZoneClose,
    Arc,
    Path,
    Vert,
    Horz,
    TepidQuadratic,
    Quadratic,
    Smooth,
)
from inkex.transforms import Vector2d
from inkex.bezier import beziertatslope, beziersplitatt


class LongShadow(inkex.EffectExtension):
    """Generate a motion path"""

    def add_arguments(self, pars):
        pars.add_argument(
            "-a",
            "--angle",
            type=float,
            default=45.0,
            help="direction of the motion vector",
        )
        pars.add_argument(
            "-m",
            "--magnitude",
            type=float,
            default=100.0,
            help="magnitude of the motion vector",
        )
        pars.add_argument(
            "-f",
            "--fillwithstroke",
            type=inkex.Boolean,
            default=False,
            help="fill shadow with stroke color if set",
        )

    @staticmethod
    def makeface(last, segment, facegroup, delx, dely):
        """translate path segment along vector"""
        elem = facegroup.add(inkex.PathElement())

        npt = segment.translate([delx, dely])

        # reverse direction of path segment
        if isinstance(segment, Curve):
            rev = Curve(npt.x3, npt.y3, npt.x2, npt.y2, last[0] + delx, last[1] + dely)
        elif isinstance(segment, Line):
            rev = Line(last[0] + delx, last[1] + dely)
        else:
            raise RuntimeError("Unexpected segment type {}".format(type(segment)))

        elem.path = inkex.Path(
            [
                Move(last[0], last[1]),
                segment,
                npt.to_line(Vector2d()),
                rev,
                ZoneClose(),
            ]
        )

    def effect(self):
        delx = math.cos(math.radians(self.options.angle)) * self.options.magnitude
        dely = math.sin(math.radians(self.options.angle)) * self.options.magnitude
        for node in self.svg.selection.filter_nonzero(inkex.PathElement):
            group = node.getparent().add(inkex.Group())
            facegroup = group.add(inkex.Group())
            group.append(node)

            # we want delx and dely values to be correct even for the transformed path,
            # so transform them back, but ignore the translate of the transform
            trans = -node.transform
            local_delx = trans.a * delx + trans.c * dely
            local_dely = trans.b * delx + trans.d * dely

            if node.transform:
                group.transform = node.transform
                node.transform = None

            facegroup.style = node.style
            if self.options.fillwithstroke:
                stroke = facegroup.style("stroke")
                if stroke is not None and isinstance(stroke, inkex.Color):
                    facegroup.style["fill"] = stroke
                    facegroup.style["fill-opacity"] = facegroup.style("stroke-opacity")
            reset_origin = True
            for cmd_proxy in node.path.to_absolute().proxy_iterator():
                # for each subpath, reset the origin of the following computations to the first
                # node of the subpath -> i.e. after a Z command, move the origin to the end point
                # of the next command
                if reset_origin:
                    first_point = cmd_proxy.end_point
                    reset_origin = False
                if isinstance(cmd_proxy.command, ZoneClose):
                    reset_origin = True
                self.process_segment(
                    cmd_proxy, facegroup, local_delx, local_dely, first_point
                )

    @staticmethod
    def process_segment(cmd_proxy, facegroup, delx, dely, first_point):
        """Process each segments"""

        segments = []
        if isinstance(
            cmd_proxy.command, (Curve, Smooth, TepidQuadratic, Quadratic, Arc)
        ):
            prev = cmd_proxy.previous_end_point
            for curve in cmd_proxy.to_curves():
                bez = [prev] + curve.to_bez()
                prev = curve.end_point(cmd_proxy.first_point, prev)
                tees = [t for t in beziertatslope(bez, (dely, delx)) if 0 < t < 1]
                tees.sort()
                if len(tees) == 1:
                    one, two = beziersplitatt(bez, tees[0])
                    segments.append(Curve(*(one[1] + one[2] + one[3])))
                    segments.append(Curve(*(two[1] + two[2] + two[3])))
                elif len(tees) == 2:
                    one, two = beziersplitatt(bez, tees[0])
                    two, three = beziersplitatt(two, tees[1])
                    segments.append(Curve(*(one[1] + one[2] + one[3])))
                    segments.append(Curve(*(two[1] + two[2] + two[3])))
                    segments.append(Curve(*(three[1] + three[2] + three[3])))
                else:
                    segments.append(curve)
        elif isinstance(cmd_proxy.command, (Line, Curve)):
            segments.append(cmd_proxy.command)
        elif isinstance(cmd_proxy.command, ZoneClose):
            segments.append(Line(*first_point))
        elif isinstance(cmd_proxy.command, (Vert, Horz)):
            segments.append(cmd_proxy.command.to_line(cmd_proxy.end_point))

        for seg in Path(
            [Move(*cmd_proxy.previous_end_point)] + segments
        ).proxy_iterator():
            if isinstance(seg.command, Move):
                continue
            LongShadow.makeface(
                seg.previous_end_point, seg.command, facegroup, delx, dely
            )


if __name__ == "__main__":
    LongShadow().run()