kev/Drawer/GVision/MLMicroStructure/mlgeos/geos/algorithm/RayCrossingCounter.h

/**********************************************************************
 *
 * GEOS - Geometry Engine Open Source
 * http://geos.osgeo.org
 *
 * 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: algorithm/RayCrossingCounter.java rev. 1.2 (JTS-1.9)
 *
 **********************************************************************/

#ifndef GEOS_ALGORITHM_RAYCROSSINGCOUNTER_H
#define GEOS_ALGORITHM_RAYCROSSINGCOUNTER_H

#include <geos/export.h>
#include <geos/geom/Location.h>

#include <vector>

// forward declarations
namespace geos {
namespace geom {
class Coordinate;
class CoordinateSequence;
}
}


namespace geos {
namespace algorithm {

/** \brief
 * Counts the number of segments crossed by a horizontal ray extending to the
 * right from a given point, in an incremental fashion.
 *
 * This can be used to determine whether a point lies in a polygonal geometry.
 * The class determines the situation where the point lies exactly on a segment.
 * When being used for Point-In-Polygon determination, this case allows
 * short-circuiting the evaluation.
 *
 * This class handles polygonal geometries with any number of shells and holes.
 * The orientation of the shell and hole rings is unimportant.
 * In order to compute a correct location for a given polygonal geometry,
 * it is essential that **all** segments are counted which
 *
 * - touch the ray
 * - lie in in any ring which may contain the point
 *
 * The only exception is when the point-on-segment situation is detected, in
 * which case no further processing is required.
 * The implication of the above rule is that segments which can be a priori
 * determined to *not* touch the ray (i.e. by a test of their bounding box or
 * Y-extent) do not need to be counted. This allows for optimization by indexing.
 *
 * @author Martin Davis
 */
class GEOS_DLL RayCrossingCounter {
private:
    const geom::Coordinate& point;

    int crossingCount;

    // true if the test point lies on an input segment
    bool isPointOnSegment;

    // Declare type as noncopyable
    RayCrossingCounter(const RayCrossingCounter& other) = delete;
    RayCrossingCounter& operator=(const RayCrossingCounter& rhs) = delete;

public:
    /** \brief
     * Determines the [Location](@ref geom::Location) of a point in a ring.
     *
     * This method is an exemplar of how to use this class.
     *
     * @param p the point to test
     * @param ring an array of Coordinates forming a ring
     * @return the location of the point in the ring
     */
    static geom::Location locatePointInRing(const geom::Coordinate& p,
                                 const geom::CoordinateSequence& ring);

    /// Semantically equal to the above, just different args encoding
    static geom::Location locatePointInRing(const geom::Coordinate& p,
                                 const std::vector<const geom::Coordinate*>& ring);

    RayCrossingCounter(const geom::Coordinate& p_point)
        : point(p_point),
          crossingCount(0),
          isPointOnSegment(false)
    { }

    /** \brief
     * Counts a segment
     *
     * @param p1 an endpoint of the segment
     * @param p2 another endpoint of the segment
     */
    void countSegment(const geom::Coordinate& p1,
                      const geom::Coordinate& p2);

    /** \brief
     * Reports whether the point lies exactly on one of the supplied segments.
     *
     * This method may be called at any time as segments are processed.
     * If the result of this method is `true`, no further segments need
     * be supplied, since the result will never change again.
     *
     * @return `true` if the point lies exactly on a segment
     */
    bool
    isOnSegment()
    {
        return isPointOnSegment;
    }

    /** \brief
     * Gets the [Location](@ref geom::Location) of the point relative to
     * the ring, polygon or multipolygon from which the processed
     * segments were provided.
     *
     * This method only determines the correct location
     * if **all** relevant segments must have been processed.
     *
     * @return the Location of the point
     */
    geom::Location getLocation();

    /** \brief
     * Tests whether the point lies in or on the ring, polygon or
     * multipolygon from which the processed segments were provided.
     *
     * This method only determines the correct location if **all** relevant
     * segments must have been processed.
     *
     * @return `true` if the point lies in or on the supplied polygon
     */
    bool isPointInPolygon();

};

} // geos::algorithm
} // geos

#endif // GEOS_ALGORITHM_RAYCROSSINGCOUNTER_H