CommonBitsRemover.cpp

/**********************************************************************
 *
 * GEOS - Geometry Engine Open Source
 * http://geos.osgeo.org
 *
 * Copyright (C) 2005-2006 Refractions Research Inc.
 * Copyright (C) 2001-2002 Vivid Solutions 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.
 *
 **********************************************************************/

#include <geos/precision/CommonBitsRemover.h>
#include <geos/precision/CommonBits.h>
// for CommonCoordinateFilter inheritance
#include <geos/geom/CoordinateFilter.h>
#include <geos/geom/Coordinate.h>
#include <geos/geom/Geometry.h>
#include <geos/util.h>

#include <cassert>

#ifndef GEOS_DEBUG
#define GEOS_DEBUG 0
#endif

#if GEOS_DEBUG
#include <iostream>
#endif

using namespace geos::geom;

namespace geos {
namespace precision { // geos.precision

class Translater: public geom::CoordinateFilter {

private:

    geom::Coordinate trans;

public:

    Translater(geom::Coordinate& newTrans)
        :
        trans(newTrans)
    {}

    void
    filter_ro(const geom::Coordinate* coord) override  //Not used
    {
        ::geos::ignore_unused_variable_warning(coord);
        assert(0);
    }

    void
    filter_rw(geom::Coordinate* coord) const override
    {
        coord->x += trans.x;
        coord->y += trans.y;
    }
};


class CommonCoordinateFilter: public geom::CoordinateFilter {
private:
    CommonBits commonBitsX;
    CommonBits commonBitsY;
public:

    void
    filter_rw(geom::Coordinate* coord) const override
    {
        // CommonCoordinateFilter is a read-only filter
        ::geos::ignore_unused_variable_warning(coord);
        assert(0);
    }

    void
    filter_ro(const geom::Coordinate* coord) override
    {
        commonBitsX.add(coord->x);
        commonBitsY.add(coord->y);
    }

    void
    getCommonCoordinate(geom::Coordinate& c)
    {
        c = Coordinate(commonBitsX.getCommon(),
                       commonBitsY.getCommon());
    }

};


CommonBitsRemover::CommonBitsRemover()
{
    ccFilter = new CommonCoordinateFilter();
}

CommonBitsRemover::~CommonBitsRemover()
{
    delete ccFilter;
}

/**
 * Add a geometry to the set of geometries whose common bits are
 * being computed.  After this method has executed the
 * common coordinate reflects the common bits of all added
 * geometries.
 *
 * @param geom a Geometry to test for common bits
 */
void
CommonBitsRemover::add(const Geometry* geom)
{
    geom->apply_ro(ccFilter);
    ccFilter->getCommonCoordinate(commonCoord);
}

/**
 * The common bits of the Coordinates in the supplied Geometries.
 */
Coordinate&
CommonBitsRemover::getCommonCoordinate()
{
    return commonCoord;
}

/**
 * Removes the common coordinate bits from a Geometry.
 * The coordinates of the Geometry are changed.
 *
 * @param geom the Geometry from which to remove the common coordinate bits
 * @return the shifted Geometry
 */
void
CommonBitsRemover::removeCommonBits(Geometry* geom)
{
    if(commonCoord.x == 0.0 && commonCoord.y == 0.0) {
        return;
    }

    Coordinate invCoord(commonCoord);
    invCoord.x = -invCoord.x;
    invCoord.y = -invCoord.y;

    Translater trans(invCoord);
    geom->apply_rw(&trans);
    geom->geometryChanged();

#if GEOS_DEBUG
    std::cerr << "CommonBits removed: " << *geom << std::endl;
#endif
}

/**
 * Adds the common coordinate bits back into a Geometry.
 * The coordinates of the Geometry are changed.
 *
 * @param geom the Geometry to which to add the common coordinate bits
 * @return the shifted Geometry
 */
Geometry*
CommonBitsRemover::addCommonBits(Geometry* geom)
{
#if GEOS_DEBUG
    std::cerr << "CommonBits before add: " << *geom << std::endl;
#endif

    Translater trans(commonCoord);

    geom->apply_rw(&trans);
    geom->geometryChanged();

#if GEOS_DEBUG
    std::cerr << "CommonBits added: " << *geom << std::endl;
#endif

    return geom;
}

} // namespace geos.precision
} // namespace geos