CascadedUnion.h

/**********************************************************************
 *
 * GEOS - Geometry Engine Open Source
 * http://trac.osgeo.org/geos
 *
 * Copyright (C) 2011 Sandro Santilli <strk@keybit.net>
 *
 * 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: ORIGINAL WORK, generalization of CascadedPolygonUnion
 *
 **********************************************************************/
 
#ifndef GEOS_OP_UNION_CASCADEDUNION_H
#define GEOS_OP_UNION_CASCADEDUNION_H
 
#include <geos/export.h>
 
#include <vector>
#include <algorithm>
 
#include "GeometryListHolder.h"
 
// Forward declarations
namespace geos {
    namespace geom {
        class GeometryFactory;
        class Geometry;
        class Geometry;
        class Envelope;
    }
    namespace index {
        namespace strtree {
            class ItemsList;
        }
    }
}
 
namespace geos {
namespace operation { // geos::operation
namespace geounion {  // geos::operation::geounion

class GEOS_DLL CascadedUnion 
{
private:
    const std::vector<geom::Geometry*>* inputGeoms;
    geom::GeometryFactory const* geomFactory;

    static int const STRTREE_NODE_CAPACITY = 4;
 
public:
    CascadedUnion();

    static geom::Geometry* Union(std::vector<geom::Geometry*>* geoms);

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

    CascadedUnion(const std::vector<geom::Geometry*>* geoms)
      : inputGeoms(geoms),
        geomFactory(NULL)
    {}

    geom::Geometry* Union();
 
private:
    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* unionOptimized(geom::Geometry* g0, geom::Geometry* g1);

    geom::Geometry* unionUsingEnvelopeIntersection(geom::Geometry* g0, 
        geom::Geometry* g1, geom::Envelope const& common);
 
    geom::Geometry* extractByEnvelope(geom::Envelope const& env, 
        geom::Geometry* geom, std::vector<geom::Geometry*>& disjointGeoms);

    static geom::Geometry* unionActual(geom::Geometry* g0, geom::Geometry* g1);
};
 
} // namespace geos::operation::union
} // namespace geos::operation
} // namespace geos
 
#endif