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Diffstat (limited to 'svg-flatten/src/svg_geom.cpp')
| -rw-r--r-- | svg-flatten/src/svg_geom.cpp | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/svg-flatten/src/svg_geom.cpp b/svg-flatten/src/svg_geom.cpp new file mode 100644 index 0000000..385e848 --- /dev/null +++ b/svg-flatten/src/svg_geom.cpp @@ -0,0 +1,182 @@ +/* + * 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 <sstream> +#include <queue> +#include <assert.h> +#include <cairo.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; +} + +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(); + Path tri = { { bbox.left, bbox.top }, nod->Childs[0]->Contour[0], nod->Childs[0]->Contour[1], { bbox.right, bbox.top } }; + c.AddPath(tri, ptClip, true); + + c.StrictlySimple(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.Execute(ctDifference, todo.emplace(), pftNonZero); + c.Execute(ctIntersection, todo.emplace(), pftNonZero); + } + } +} + +/* 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(); + } +} + + +/* Intersect two clip paths. Both must share a coordinate system. */ +void gerbolyze::combine_clip_paths(Paths &in_a, Paths &in_b, Paths &out) { + Clipper c; + c.StrictlySimple(true); + c.AddPaths(in_a, ptClip, /* closed */ true); + c.AddPaths(in_b, ptSubject, /* closed */ true); + /* Nonzero fill since both input clip paths must already have been preprocessed by clipper. */ + c.Execute(ctIntersection, out, pftNonZero); +} + +/* Transform given clipper paths under the given cairo transform. If no transform is given, use cairo's current + * user-to-device transform. */ +void gerbolyze::transform_paths(cairo_t *cr, Paths &paths, cairo_matrix_t *mat) { + cairo_save(cr); + if (mat != nullptr) { + cairo_set_matrix(cr, mat); + } + + for (Path &p : paths) { + transform(p.begin(), p.end(), p.begin(), + [cr](IntPoint p) -> IntPoint { + double x = p.X / clipper_scale, y = p.Y / clipper_scale; + cairo_user_to_device(cr, &x, &y); + return { (cInt)round(x * clipper_scale), (cInt)round(y * clipper_scale) }; + }); + } + + cairo_restore(cr); +} + + |