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/*
* 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 "svg_geom.h"
#include <cmath>
#include <string>
#include <iostream>
#include <sstream>
#include <queue>
#include <assert.h>
#include "svg_import_defs.h"
using namespace ClipperLib;
using namespace std;
/* Get bounding box of a Clipper Paths */
IntRect gerbolyze::get_paths_bounds(const Paths &paths) {
if (paths.empty()) {
return {0, 0, 0, 0};
}
if (paths[0].empty()) {
return {0, 0, 0, 0};
}
IntPoint p0 = paths[0][0];
cInt x0=p0.X, y0=p0.Y, x1=p0.X, y1=p0.Y;
for (const Path &p : paths) {
for (const IntPoint ip : p) {
if (ip.X < x0)
x0 = ip.X;
if (ip.Y < y0)
y0 = ip.Y;
if (ip.X > x1)
x1 = ip.X;
if (ip.Y > y1)
y1 = ip.Y;
}
}
return {x0, y0, x1, y1};
}
enum ClipperLib::PolyFillType gerbolyze::clipper_fill_rule(const pugi::xml_node &node) {
string val(node.attribute("fill-rule").value());
if (val == "evenodd")
return ClipperLib::pftEvenOdd;
else
return ClipperLib::pftNonZero; /* default */
}
enum ClipperLib::EndType gerbolyze::clipper_end_type(const pugi::xml_node &node) {
string val(node.attribute("stroke-linecap").value());
if (val == "round")
return ClipperLib::etOpenRound;
if (val == "square")
return ClipperLib::etOpenSquare;
return ClipperLib::etOpenButt;
}
enum ClipperLib::JoinType gerbolyze::clipper_join_type(const pugi::xml_node &node) {
string val(node.attribute("stroke-linejoin").value());
if (val == "round")
return ClipperLib::jtRound;
if (val == "bevel")
return ClipperLib::jtSquare;
return ClipperLib::jtMiter;
}
/* Some debugging helpers */
static double toplevel_winding_direction(PolyNode &ptree) {
double sum = 0.0;
size_t sz = ptree.Contour.size();
for (size_t i=0; i<sz; i++) {
size_t j = (i+1) % sz;
double x1 = ptree.Contour[i].X, y1 = ptree.Contour[i].Y;
double x2 = ptree.Contour[j].X, y2 = ptree.Contour[j].Y;
sum += (x2-x1)*(y2+y1);
}
return sum;
}
static void dump_ptree(PolyNode &ptree) {
/* dumps node count, winding direction and tree structure */
double sum = toplevel_winding_direction(ptree);
char sign = '.';
if (sum > 0) {
sign = '+';
} else if (sum < 0) {
sign = '-';
}
cerr << sign << ptree.Contour.size() << "[";
for (size_t i=0; i<ptree.ChildCount(); i++) {
if (i > 0) {
cerr << ",";
}
dump_ptree(*ptree.Childs[i]);
}
cerr << "]";
}
static void dump_clipper2svg(Path &path, string stroke) {
/* dumps the ptree to SVG */
/* use together with
cerr << "<svg width=\"200\" height=\"200\" xmlns=\"http://www.w3.org/2000/svg\">" << endl;
...
dump_clipper2svg(...); // can be used multiple times
...
cerr << "</svg>" << endl;
*/
size_t sz = path.size();
if (sz == 0) {
return;
}
cerr << "<path fill=\"" << stroke << "\" d=\"M ";
for (size_t i=0; i<sz; i++) {
if (i>0) {
cerr << " L ";
}
cerr << (path[i].X / 1e7) << ", " << (path[i].Y / 1e7);
}
cerr << " Z\"/>" << endl;
}
static void dehole_polytree_worker(PolyNode &ptree, Paths &out, queue<PolyTree> &todo) {
for (int i=0; i<ptree.ChildCount(); i++) {
PolyNode *nod = ptree.Childs[i];
assert(nod);
assert(!nod->IsHole());
/* First, recursively process inner polygons. */
for (int j=0; j<nod->ChildCount(); j++) {
PolyNode *child = nod->Childs[j];
assert(child);
assert(child->IsHole());
if (child->ChildCount() > 0) {
dehole_polytree_worker(*child, out, todo);
}
}
if (nod->ChildCount() == 0) {
out.push_back(nod->Contour);
} else {
/* Do not add children's children, those were handled in the recursive call above */
Clipper c;
c.AddPath(nod->Contour, ptSubject, /* closed= */ true);
for (int k=0; k<nod->ChildCount(); k++) {
c.AddPath(nod->Childs[k]->Contour, ptSubject, /* closed= */ true);
}
/* Find a viable cut: Cut from top-left bounding box corner, through two subsequent points on the hole
* outline and to top-right bbox corner. */
IntRect bbox = c.GetBounds();
/* Clipper might return a polygon with a zero-length, or an exactly vertical outline segment. We iterate
* until we find a point that has a different X coordinate than our starting point. If we can't find one
* because the polygon only consists only of points on a vertical line, we can safely discard it and do
* nothing since it has zero area anyway. */
for (size_t i=1; i<nod->Childs[0]->Contour.size(); i++) {
if (nod->Childs[0]->Contour[i].X == nod->Childs[0]->Contour[i-1].X) {
continue;
}
/* We now have found that Contour[i-1] - Contour[i] has a non-zero horizontal component, and is a
* candidate for our cut. However, we have to make sure that the first point is left (lower X
* coordinate) of the second point, or the cutting polygon we create here would have a
* self-intersection, which with high likelihood would lead to a new hole being created when cutting.
*/
int a=i-1, b=i;
if (nod->Childs[0]->Contour[i].X < nod->Childs[0]->Contour[i-1].X) {
/* Swap points */
a = i;
b = i-1;
}
Path tri = { { bbox.left, bbox.top }, nod->Childs[0]->Contour[a], nod->Childs[0]->Contour[b], { bbox.right, bbox.top } };
c.AddPath(tri, ptClip, true);
/* Execute twice, once for intersection fragment and once for difference fragment. Note that this will yield
* at least two, but possibly more polygons. */
c.StrictlySimple(true);
c.Execute(ctDifference, todo.emplace(), pftNonZero);
c.Execute(ctIntersection, todo.emplace(), pftNonZero);
break;
}
}
}
}
/* Take a Clipper polytree, i.e. a description of a set of polygons, their holes and their inner polygons, and remove
* all holes from it. We remove holes by splitting each polygon that has a hole into two or more pieces so that the hole
* is no more. These pieces perfectly fit each other so there is no visual or functional difference.
*/
void gerbolyze::dehole_polytree(PolyTree &ptree, Paths &out) {
queue<PolyTree> todo;
dehole_polytree_worker(ptree, out, todo);
while (!todo.empty()) {
dehole_polytree_worker(todo.front(), out, todo);
todo.pop();
}
}
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