EVOLUTION-MANAGER

Edit File: BufferOp.h

/**********************************************************************
 *
 * GEOS - Geometry Engine Open Source
 * http://geos.osgeo.org
 *
 * Copyright (C) 2009-2011 Sandro Santilli <strk@kbt.io>
 * Copyright (C) 2005-2007 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.
 *
 **********************************************************************
 *
 * Last port: operation/buffer/BufferOp.java r378 (JTS-1.12)
 *
 **********************************************************************/

#ifndef GEOS_OP_BUFFER_BUFFEROP_H
#define GEOS_OP_BUFFER_BUFFEROP_H

#include <geos/export.h>
#include <geos/operation/buffer/BufferParameters.h> // for enum values

#include <geos/util/TopologyException.h> // for composition

#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable: 4251) // warning C4251: needs to have dll-interface to be used by clients of class
#endif

// Forward declarations
namespace geos {
namespace geom {
class PrecisionModel;
class Geometry;
}
}

namespace geos {
namespace operation { // geos.operation
namespace buffer { // geos.operation.buffer

/**
 * \class BufferOp opBuffer.h geos/opBuffer.h
 *
 * \brief
 * Computes the buffer of a geometry, for both positive and negative
 * buffer distances.
 *
 * In GIS, the positive (or negative) buffer of a geometry is defined as
 * the Minkowski sum (or difference) of the geometry
 * with a circle with radius equal to the absolute value of the buffer
 * distance.
 * In the CAD/CAM world buffers are known as *offset curves*.
 * In morphological analysis the operation of positive and negative buffering
 * is referred to as *erosion* and *dilation*.
 *
 * The buffer operation always returns a polygonal result.
 * The negative or zero-distance buffer of lines and points is always
 * an empty Polygon.
 *
 * Since true buffer curves may contain circular arcs,
 * computed buffer polygons can only be approximations to the true geometry.
 * The user can control the accuracy of the curve approximation by specifying
 * the number of linear segments with which to approximate a curve.
 *
 * The end cap style of a linear buffer may be specified.
 * The following end cap styles are supported:
 * - CAP_ROUND - the usual round end caps
 * - CAP_BUTT - end caps are truncated flat at the line ends
 * - CAP_SQUARE - end caps are squared off at the buffer distance
 *   beyond the line ends
 *
 */
class GEOS_DLL BufferOp {

private:

/** \brief
     *  A number of digits of precision which leaves some computational "headroom"
     *  for floating point operations.
     *
     *  This value should be less than the decimal precision of double-precision values (16).
     */
    static const int MAX_PRECISION_DIGITS = 12;

/**
     * Compute a reasonable scale factor to limit the precision of
     * a given combination of Geometry and buffer distance.
     * The scale factor is based on a heuristic.
     *
     * @param g the Geometry being buffered
     *
     * @param distance the buffer distance
     *
     * @param maxPrecisionDigits the mzx # of digits that should be
     *        allowed by the precision determined by the
     *        computed scale factor
     *
     * @return a scale factor that allows a reasonable amount of
     *         precision for the buffer computation
     */
    static double precisionScaleFactor(const geom::Geometry* g,
                                       double distance, int maxPrecisionDigits);

const geom::Geometry* argGeom;

util::TopologyException saveException;

double distance;

//int quadrantSegments;
    //int endCapStyle;
    BufferParameters bufParams;

geom::Geometry* resultGeometry;

void computeGeometry();

void bufferOriginalPrecision();

void bufferReducedPrecision(int precisionDigits);

void bufferReducedPrecision();

void bufferFixedPrecision(const geom::PrecisionModel& fixedPM);

public:

enum {
        /// Specifies a round line buffer end cap style.
        /// @deprecated use BufferParameters
        CAP_ROUND = BufferParameters::CAP_ROUND,

/// Specifies a butt (or flat) line buffer end cap style.
        /// @deprecated use BufferParameters
        CAP_BUTT = BufferParameters::CAP_FLAT,

/// Specifies a square line buffer end cap style.
        /// @deprecated use BufferParameters
        CAP_SQUARE = BufferParameters::CAP_SQUARE
    };

/** \brief
     * Computes the buffer for a geometry for a given buffer distance
     * and accuracy of approximation.
     *
     * @param g the geometry to buffer
     * @param distance the buffer distance
     * @param quadrantSegments the number of segments used to
     *        approximate a quarter circle
     * @param endCapStyle line buffer end cap style (default: BufferParameters::CAP_ROUND)
     * @return the buffer of the input geometry
     *
     */
    static geom::Geometry* bufferOp(const geom::Geometry* g,
                                    double distance,
                                    int quadrantSegments =
                                        BufferParameters::DEFAULT_QUADRANT_SEGMENTS,
                                    int endCapStyle = BufferParameters::CAP_ROUND);

/** \brief
     * Initializes a buffer computation for the given geometry.
     *
     * @param g the geometry to buffer
     */
    BufferOp(const geom::Geometry* g)
        :
        argGeom(g),
        bufParams(),
        resultGeometry(nullptr)
    {
    }

/** \brief
     * Initializes a buffer computation for the given geometry
     * with the given set of parameters.
     *
     * @param g the geometry to buffer
     * @param params the buffer parameters to use. This class will
     *               copy it to private memory.
     */
    BufferOp(const geom::Geometry* g, const BufferParameters& params)
        :
        argGeom(g),
        bufParams(params),
        resultGeometry(nullptr)
    {
    }

/** \brief
     * Specifies the end cap style of the generated buffer.
     *
     * The styles supported are CAP_ROUND, CAP_BUTT, and CAP_SQUARE.
     * The default is CAP_ROUND.
     *
     * @param nEndCapStyle the end cap style to specify
     */
    inline void setEndCapStyle(int nEndCapStyle);

/** \brief
     * Sets the number of segments used to approximate a angle fillet
     *
     * @param nQuadrantSegments the number of segments in a fillet for a quadrant
     */
    inline void setQuadrantSegments(int nQuadrantSegments);

/** \brief
     * Sets whether the computed buffer should be single-sided.
     *
     * A single-sided buffer is constructed on only one side
     * of each input line.
     *
     * The side used is determined by the sign of the buffer distance:
     * - a positive distance indicates the left-hand side
     * - a negative distance indicates the right-hand side
     *
     * The single-sided buffer of point geometries is
     * the same as the regular buffer.
     *
     * The End Cap Style for single-sided buffers is
     * always ignored,
     * and forced to the equivalent of `CAP_FLAT`.
     *
     * @param isSingleSided `true` if a single-sided buffer
     *                      should be constructed
     */
    inline void setSingleSided(bool isSingleSided);

/** \brief
     * Returns the buffer computed for a geometry for a given buffer
     * distance.
     *
     * @param nDistance the buffer distance
     * @return the buffer of the input geometry
     */
    geom::Geometry* getResultGeometry(double nDistance);

};

// BufferOp inlines
void
BufferOp::setQuadrantSegments(int q)
{
    bufParams.setQuadrantSegments(q);
}

void
BufferOp::setEndCapStyle(int s)
{
    bufParams.setEndCapStyle((BufferParameters::EndCapStyle)s);
}

void
BufferOp::setSingleSided(bool isSingleSided)
{
    bufParams.setSingleSided(isSingleSided);
}

} // namespace geos::operation::buffer
} // namespace geos::operation
} // namespace geos

#ifdef _MSC_VER
#pragma warning(pop)
#endif

#endif // ndef GEOS_OP_BUFFER_BUFFEROP_H