pointlocator.h

在Linux下做的QuadTree的程序

/**********************************************************************
 * $Id: PointLocator.h 1820 2006-09-06 16:54:23Z mloskot $
 *
 * GEOS - Geometry Engine Open Source
 * http://geos.refractions.net
 *
 * 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.
 *
 **********************************************************************/

#ifndef GEOS_ALGORITHM_POINTLOCATOR_H
#define GEOS_ALGORITHM_POINTLOCATOR_H

#include <geos/geom/Location.h> // for inlines

// Forward declarations
namespace geos {
	namespace geom {
		class Coordinate;
		class Geometry;
		class LinearRing;
		class LineString;
		class Polygon;
	}
}

namespace geos {
namespace algorithm { // geos::algorithm

/**
 * \class PointLocator geosAlgorithm.h geos/geosAlgorithm.h
 *
 * \brief
 * Computes the topological relationship (Location)
 * of a single point to a Geometry.
 *
 * The algorithm obeys the SFS boundaryDetermination rule to correctly determine
 * whether the point lies on the boundary or not.
 *
 * Notes:
 *	- instances of this class are not reentrant.
 *	- LinearRing objects do not enclose any area
 *	  points inside the ring are still in the EXTERIOR of the ring.
 *
 * Last port: algorithm/PointLocator.java rev. 1.26 (JTS-1.7+)
 */
class PointLocator {
public:
	PointLocator() {}
	~PointLocator() {}

	/**
	 * Computes the topological relationship (Location) of a single point
	 * to a Geometry.
	 * It handles both single-element
	 * and multi-element Geometries.
	 * The algorithm for multi-part Geometries
	 * takes into account the boundaryDetermination rule.
	 *
	 * @return the Location of the point relative to the input Geometry
	 */
	int locate(const geom::Coordinate& p, const geom::Geometry *geom);

	/**
	 * Convenience method to test a point for intersection with
	 * a Geometry
	 *
	 * @param p the coordinate to test
	 * @param geom the Geometry to test
	 * @return <code>true</code> if the point is in the interior or boundary of the Geometry
	 */
	bool intersects(const geom::Coordinate& p, const geom::Geometry *geom) {
		return locate(p, geom) != geom::Location::EXTERIOR;
	}

private:

	bool isIn;         // true if the point lies in or on any Geometry element

	int numBoundaries;    // the number of sub-elements whose boundaries the point lies in

	void computeLocation(const geom::Coordinate& p, const geom::Geometry *geom);

	void updateLocationInfo(int loc);

	int locate(const geom::Coordinate& p, const geom::LineString *l);

	int locateInPolygonRing(const geom::Coordinate& p, const geom::LinearRing *ring);

	int locate(const geom::Coordinate& p, const geom::Polygon *poly);

};

} // namespace geos::algorithm
} // namespace geos


#endif // GEOS_ALGORITHM_POINTLOCATOR_H

/**********************************************************************
 * $Log$
 * Revision 1.1  2006/03/09 16:46:48  strk
 * geos::geom namespace definition, first pass at headers split
 *
 **********************************************************************/