RingClipper.h

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/**********************************************************************
 *
 * GEOS - Geometry Engine Open Source
 * http://geos.osgeo.org
 *
 * Copyright (C) 2020 Paul Ramsey <pramsey@cleverelephant.ca>
 *
 * This is free software; you can redistribute and/or modify it under
 * the terms of the GNU Lesser General Public Licence as published
 * by the Free Software Foundation.
 * See the COPYING file for more information.
 *
 **********************************************************************/

#pragma once

#include <geos/export.h>

#include <geos/geom/Envelope.h>
#include <geos/geom/CoordinateArraySequence.h>
#include <geos/geom/CoordinateSequence.h>

// Forward declarations
namespace geos {
namespace geom {
class Coordinate;
class CoordinateSequence;
class CoordinateArraySequence;
}
}

using namespace geos::geom;

namespace geos {      // geos.
namespace operation { // geos.operation
namespace overlayng { // geos.operation.overlayng

class GEOS_DLL RingClipper {

private:

    // Constants
    static constexpr int BOX_LEFT = 3;
    static constexpr int BOX_TOP = 2;
    static constexpr int BOX_RIGHT = 1;
    static constexpr int BOX_BOTTOM = 0;

    // Members
    // const Envelope* clipEnv;
    double clipEnvMinY;
    double clipEnvMaxY;
    double clipEnvMinX;
    double clipEnvMaxX;

    // Methods

    std::unique_ptr<CoordinateArraySequence> clipToBoxEdge(const CoordinateSequence* pts, int edgeIndex, bool closeRing) const;

    void intersection(const Coordinate& a, const Coordinate& b, int edgeIndex, Coordinate& rsltPt) const;
    double intersectionLineY(const Coordinate& a, const Coordinate& b, double y) const;
    double intersectionLineX(const Coordinate& a, const Coordinate& b, double x) const;
    bool isInsideEdge(const Coordinate& p, int edgeIndex) const;


public:

    RingClipper(const Envelope* env)
        : clipEnvMinY(env->getMinY())
        , clipEnvMaxY(env->getMaxY())
        , clipEnvMinX(env->getMinX())
        , clipEnvMaxX(env->getMaxX())
        {};

    std::unique_ptr<CoordinateArraySequence> clip(const CoordinateSequence* cs) const;

};


} // namespace geos.operation.overlayng
} // namespace geos.operation
} // namespace geos