/*
* This file is part of gerbolyze, a vector image preprocessing toolchain
* Copyright (C) 2021 Jan Sebastian Götte <gerbolyze@jaseg.de>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include <cmath>
#include <assert.h>
#include <iostream>
#include <sstream>
#include "cairo_clipper.hpp"
#include "svg_import_defs.h"
#include "svg_path.h"
using namespace std;
static void clipper_add_cairo_path(cairo_t *cr, ClipperLib::Clipper &c, bool closed) {
ClipperLib::Paths in_poly;
ClipperLib::cairo::cairo_to_clipper(cr, in_poly, CAIRO_PRECISION, ClipperLib::cairo::tNone);
c.AddPaths(in_poly, ClipperLib::ptSubject, closed);
}
static void path_to_clipper_via_cairo(cairo_t *cr, ClipperLib::Clipper &c, const pugi::char_t *path_data) {
istringstream d(path_data);
string cmd;
double x, y, c1x, c1y, c2x, c2y;
bool first = true;
bool path_is_empty = true;
while (!d.eof()) {
d >> cmd;
assert (!d.fail());
assert(!first || cmd == "M");
if (cmd == "Z") { /* Close path */
cairo_close_path(cr);
clipper_add_cairo_path(cr, c, /* closed= */ true);
cairo_new_path(cr);
path_is_empty = true;
} else if (cmd == "M") { /* Move to */
d >> x >> y;
/* We need to transform all points ourselves here, and cannot use the transform feature of cairo_to_clipper:
* Our transform may contain offsets, and clipper only passes its data into cairo's transform functions
* after scaling up to its internal fixed-point ints, but it does not scale the transform accordingly. This
* means a scale/rotation we set before calling clipper works out fine, but translations get lost as they
* get scaled by something like 1e-6.
*/
cairo_user_to_device(cr, &x, &y);
assert (!d.fail());
if (!first)
clipper_add_cairo_path(cr, c, /* closed= */ false);
cairo_new_path (cr);
path_is_empty = true;
cairo_move_to(cr, x, y);
} else if (cmd == "L") { /* Line to */
d >> x >> y;
cairo_user_to_device(cr, &x, &y);
assert (!d.fail());
cairo_line_to(cr, x, y);
path_is_empty = false;
} else { /* Curve to */
assert(cmd == "C");
d >> c1x >> c1y; /* first control point */
cairo_user_to_device(cr, &c1x, &c1y);
d >> c2x >> c2y; /* second control point */
cairo_user_to_device(cr, &c2x, &c2y);
d >> x >> y; /* end point */
cairo_user_to_device(cr, &x, &y);
assert (!d.fail());
cairo_curve_to(cr, c1x, c1y, c2x, c2y, x, y);
path_is_empty = false;
}
first = false;
}
if (!path_is_empty) {
cairo_close_path(cr);
clipper_add_cairo_path(cr, c, /* closed= */ false);
}
}
void gerbolyze::load_svg_path(cairo_t *cr, const pugi::xml_node &node, ClipperLib::PolyTree &ptree) {
auto *path_data = node.attribute("d").value();
auto fill_rule = clipper_fill_rule(node);
/* For open paths, clipper does not correctly remove self-intersections. Thus, we pass everything into
* clipper twice: Once with all paths set to "closed" to compute fill areas, and once with correct
* open/closed properties for stroke offsetting. */
cairo_set_tolerance (cr, 0.1); /* FIXME make configurable, scale properly for units */
cairo_set_fill_rule(cr, CAIRO_FILL_RULE_WINDING);
ClipperLib::Clipper c;
c.StrictlySimple(true);
path_to_clipper_via_cairo(cr, c, path_data);
/* We canont clip the polygon here since that would produce incorrect results for our stroke. */
c.Execute(ClipperLib::ctUnion, ptree, fill_rule, ClipperLib::pftNonZero);
}
void gerbolyze::parse_dasharray(const pugi::xml_node &node, vector<double> &out) {
out.clear();
string val(node.attribute("stroke-dasharray").value());
if (val.empty() || val == "none")
return;
istringstream desc_stream(val);
while (!desc_stream.eof()) {
/* usvg says the array only contains unitless (px) values. I don't know what resvg does with percentages inside
* dash arrays. We just assume everything is a unitless number here. In case usvg passes through percentages,
* well, bad luck. They are a kind of weird thing inside a dash array in the first place. */
double d;
desc_stream >> d;
out.push_back(d);
}
assert(out.size() % 2 == 0); /* according to resvg spec */
}
/* Take a Clipper path in clipper-scaled document units, and apply the given SVG dash array to it. Do this by walking
* the path from start to end while emitting dashes. */
void gerbolyze::dash_path(const ClipperLib::Path &in, ClipperLib::Paths &out, const vector<double> dasharray, double dash_offset) {
out.clear();
if (dasharray.empty() || in.size() < 2) {
out.push_back(in);
return;
}
size_t dash_idx = 0;
size_t num_dashes = dasharray.size();
while (dash_offset > dasharray[dash_idx]) {
dash_offset -= dasharray[dash_idx];
dash_idx = (dash_idx + 1) % num_dashes;
}
double dash_remaining = dasharray[dash_idx] - dash_offset;
ClipperLib::Path current_dash;
current_dash.push_back(in[0]);
double dbg_total_len = 0.0;
for (size_t i=1; i<in.size(); i++) {
ClipperLib::IntPoint p1(in[i-1]), p2(in[i]);
double x1 = p1.X / clipper_scale, y1 = p1.Y / clipper_scale, x2 = p2.X / clipper_scale, y2 = p2.Y / clipper_scale;
double dist = sqrt(pow(x2-x1, 2) + pow(y2-y1, 2));
dbg_total_len += dist;
if (dist < dash_remaining) {
/* dash extends beyond this segment, append this segment and continue. */
dash_remaining -= dist;
current_dash.push_back(p2);
} else {
/* dash started in some previous segment ends in this segment */
double dash_frac = dash_remaining/dist;
double x = x1 + (x2 - x1) * dash_frac,
y = y1 + (y2 - y1) * dash_frac;
ClipperLib::IntPoint intermediate {(ClipperLib::cInt)round(x * clipper_scale), (ClipperLib::cInt)round(y * clipper_scale)};
/* end this dash */
current_dash.push_back(intermediate);
if (dash_idx%2 == 0) { /* dash */
out.push_back(current_dash);
} /* else space */
dash_idx = (dash_idx + 1) % num_dashes;
double offset = dash_remaining;
/* start next dash */
current_dash.clear();
current_dash.push_back(intermediate);
/* handle case where multiple dashes fit into this segment */
while ((dist - offset) > dasharray[dash_idx]) {
offset += dasharray[dash_idx];
double dash_frac = offset/dist;
double x = x1 + (x2 - x1) * dash_frac,
y = y1 + (y2 - y1) * dash_frac;
ClipperLib::IntPoint intermediate {(ClipperLib::cInt)round(x * clipper_scale), (ClipperLib::cInt)round(y * clipper_scale)};
/* end this dash */
current_dash.push_back(intermediate);
if (dash_idx%2 == 0) { /* dash */
out.push_back(current_dash);
} /* else space */
dash_idx = (dash_idx + 1) % num_dashes;
/* start next dash */
current_dash.clear();
current_dash.push_back(intermediate);
}
dash_remaining = dasharray[dash_idx] - (dist - offset);
current_dash.push_back(p2);
}
}
}