GeometryDistanceClusterFinder.h

/**********************************************************************
 *
 * GEOS - Geometry Engine Open Source
 * http://geos.osgeo.org
 *
 * Copyright (C) 2020-2021 Daniel Baston
 *
 * 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/operation/cluster/AbstractClusterFinder.h>
#include <geos/geom/prep/PreparedGeometry.h>
#include <geos/geom/prep/PreparedGeometryFactory.h>
 
namespace geos {
namespace operation {
namespace cluster {
 
class GEOS_DLL GeometryDistanceClusterFinder : public AbstractClusterFinder {
public:
    explicit GeometryDistanceClusterFinder(double distance) : m_distance(distance) {}
 
protected:
    bool shouldJoin(const geom::Geometry* a, const geom::Geometry *b) override {
        if (m_prep == nullptr || &(m_prep->getGeometry()) != a) {
            m_prep = geom::prep::PreparedGeometryFactory::prepare(a);
        }
 
        return m_prep->isWithinDistance(b, m_distance);
    }
 
    const geom::Envelope& queryEnvelope(const geom::Geometry* a) override {
        m_envelope = *a->getEnvelopeInternal();
        m_envelope.expandBy(m_distance);
        return m_envelope;
    }
 
private:
    std::unique_ptr<geom::prep::PreparedGeometry> m_prep;
    double m_distance;
    geom::Envelope m_envelope;
};
 
}
}
}