src/2geom/intersection-graph.h

	intersection-graph.h revision 76addc201c409e81eaaa73fe27cc0f79c4db097c
/**
 * \file
 * \brief Path intersection graph
 *//*
 * Authors:
 *   Krzysztof Kosiński <tweenk.pl@gmail.com>
 *
 * Copyright 2015 Authors
 *
 * This library is free software; you can redistribute it and/or
 * modify it either under the terms of the GNU Lesser General Public
 * License version 2.1 as published by the Free Software Foundation
 * (the "LGPL") or, at your option, under the terms of the Mozilla
 * Public License Version 1.1 (the "MPL"). If you do not alter this
 * notice, a recipient may use your version of this file under either
 * the MPL or the LGPL.
 *
 * You should have received a copy of the LGPL along with this library
 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 * You should have received a copy of the MPL along with this library
 * in the file COPYING-MPL-1.1
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
 * the specific language governing rights and limitations.
 */

#ifndef SEEN_LIB2GEOM_INTERSECTION_GRAPH_H
#define SEEN_LIB2GEOM_INTERSECTION_GRAPH_H

#include <set>
#include <vector>
#include <boost/ptr_container/ptr_vector.hpp>
#include <boost/intrusive/list.hpp>
#include <2geom/forward.h>
#include <2geom/pathvector.h>

namespace Geom {

enum InOutFlag {
    POINT_INSIDE,
    POINT_OUTSIDE,
    POINT_ON_EDGE
};

struct IntersectionVertex {
    boost::intrusive::list_member_hook<> _hook;
    PathVectorPosition pos;
    Point p; // guarantees that endpoints are exact
    IntersectionVertex *neighbor;
    bool entry; // going in +t direction enters the other path
    InOutFlag previous;
    InOutFlag next;
    bool processed; // TODO: use intrusive unprocessed list instead
};

typedef boost::intrusive::list
    < IntersectionVertex
    , boost::intrusive::member_hook
        < IntersectionVertex
        , boost::intrusive::list_member_hook<>
        , &IntersectionVertex::_hook
        >
    > IntersectionList;


class PathIntersectionGraph
{
    // this is called PathIntersectionGraph so that we can also have a class for polygons,
    // e.g. PolygonIntersectionGraph, which is going to be significantly faster
public:
    PathIntersectionGraph(PathVector const &a, PathVector const &b, Coord precision = EPSILON);

    PathVector getUnion();
    PathVector getIntersection();

private:
    PathVector _getResult(bool enter_a, bool enter_b);
    void _handleNonintersectingPaths(PathVector &result, int which, bool inside);
    bool _findUnprocessed(IntersectionList::iterator &result);

    PathVector _a, _b;
    boost::ptr_vector<IntersectionVertex> _xs;
    boost::ptr_vector<IntersectionList> _xalists;
    boost::ptr_vector<IntersectionList> _xblists;
};

} // namespace Geom

#endif // SEEN_LIB2GEOM_PATH_GRAPH_H
/*
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*/
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