CascadedPolygonUnion.h

Go to the documentation of this file.

/**********************************************************************
 *
 * GEOS - Geometry Engine Open Source
 * http://geos.osgeo.org
 *
 * Copyright (C) 2011 Sandro Santilli <strk@kbt.io>
 * Copyright (C) 2006 Refractions Research Inc.
 *
 * 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.
 *
 **********************************************************************
 *
 * Last port: operation/union/CascadedPolygonUnion.java r487 (JTS-1.12+)
 * Includes custom code to deal with https://trac.osgeo.org/geos/ticket/837
 *
 **********************************************************************/

#ifndef GEOS_OP_UNION_CASCADEDPOLYGONUNION_H
#define GEOS_OP_UNION_CASCADEDPOLYGONUNION_H

#include <geos/export.h>

#include <vector>
#include <algorithm>
#include <memory>

#include <geos/operation/union/GeometryListHolder.h>
#include <geos/operation/union/UnionStrategy.h>

// Forward declarations
namespace geos {
namespace geom {
class GeometryFactory;
class Geometry;
class Polygon;
class MultiPolygon;
class Envelope;
}
namespace index {
namespace strtree {
class ItemsList;
}
}
}

namespace geos {
namespace operation { // geos::operation
namespace geounion {  // geos::operation::geounion


class GEOS_DLL ClassicUnionStrategy : public UnionStrategy {

public:

    ClassicUnionStrategy() {};

    std::unique_ptr<geom::Geometry> Union(const geom::Geometry*, const geom::Geometry*) override;

    bool isFloatingPrecision() const override;

private:

    std::unique_ptr<geom::Geometry> unionPolygonsByBuffer(const geom::Geometry* g0, const geom::Geometry* g1);

};



class GEOS_DLL CascadedPolygonUnion {
private:
    std::vector<geom::Polygon*>* inputPolys;
    geom::GeometryFactory const* geomFactory;

    static int const STRTREE_NODE_CAPACITY = 4;

    static std::unique_ptr<geom::Geometry> restrictToPolygons(std::unique_ptr<geom::Geometry> g);

public:
    CascadedPolygonUnion();

    static geom::Geometry* Union(std::vector<geom::Polygon*>* polys);
    static geom::Geometry* Union(std::vector<geom::Polygon*>* polys, UnionStrategy* unionFun);

    template <class T>
    static geom::Geometry*
    Union(T start, T end, UnionStrategy *unionStrategy)
    {
        std::vector<geom::Polygon*> polys;
        for(T i = start; i != end; ++i) {
            const geom::Polygon* p = dynamic_cast<const geom::Polygon*>(*i);
            polys.push_back(const_cast<geom::Polygon*>(p));
        }
        return Union(&polys, unionStrategy);
    }

    static geom::Geometry* Union(const geom::MultiPolygon* polys);

    CascadedPolygonUnion(std::vector<geom::Polygon*>* polys)
        : inputPolys(polys)
        , geomFactory(nullptr)
        , unionFunction(&defaultUnionFunction)
    {}

    CascadedPolygonUnion(std::vector<geom::Polygon*>* polys, UnionStrategy* unionFun)
        : inputPolys(polys)
        , geomFactory(nullptr)
        , unionFunction(unionFun)
    {}

    geom::Geometry* Union();

private:

    UnionStrategy* unionFunction;
    ClassicUnionStrategy defaultUnionFunction;

    geom::Geometry* unionTree(index::strtree::ItemsList* geomTree);

    geom::Geometry* binaryUnion(GeometryListHolder* geoms);

    geom::Geometry* binaryUnion(GeometryListHolder* geoms, std::size_t start,
                                std::size_t end);

    GeometryListHolder* reduceToGeometries(index::strtree::ItemsList* geomTree);

    geom::Geometry* unionSafe(geom::Geometry* g0, geom::Geometry* g1);

    geom::Geometry* unionActual(geom::Geometry* g0, geom::Geometry* g1);
};





} // namespace geos::operation::union
} // namespace geos::operation
} // namespace geos

#endif