qgsdistancearea.h

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/***************************************************************************
  qgsdistancearea.h - Distance and area calculations on the ellipsoid
 ---------------------------------------------------------------------------
  Date                 : September 2005
  Copyright            : (C) 2005 by Martin Dobias
  email                : won.der at centrum.sk
 ***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#ifndef QGSDISTANCEAREA_H
#define QGSDISTANCEAREA_H

#include "qgis_core.h"
#include <QVector>
#include <QReadWriteLock>
#include "qgscoordinatetransform.h"
#include "qgsunittypes.h"
#include "qgsellipsoidutils.h"

class QgsGeometry;
class QgsAbstractGeometry;
class QgsCurve;

class CORE_EXPORT QgsDistanceArea
{
  public:

    QgsDistanceArea();

    bool willUseEllipsoid() const;

    void setSourceCrs( const QgsCoordinateReferenceSystem &crs, const QgsCoordinateTransformContext &context );

    QgsCoordinateReferenceSystem sourceCrs() const { return mCoordTransform.sourceCrs(); }

    bool setEllipsoid( const QString &ellipsoid );

    bool setEllipsoid( double semiMajor, double semiMinor );

    QString ellipsoid() const { return mEllipsoid; }

    double ellipsoidSemiMajor() const { return mSemiMajor; }

    double ellipsoidSemiMinor() const { return mSemiMinor; }

    double ellipsoidInverseFlattening() const { return mInvFlattening; }

    double measureArea( const QgsGeometry &geometry ) const;

    double measureLength( const QgsGeometry &geometry ) const;

    double measurePerimeter( const QgsGeometry &geometry ) const;

    double measureLine( const QVector<QgsPointXY> &points ) const;

    double measureLine( const QgsPointXY &p1, const QgsPointXY &p2 ) const;

    double measureLineProjected( const QgsPointXY &p1, double distance = 1, double azimuth = M_PI_2, QgsPointXY *projectedPoint SIP_OUT = nullptr ) const;

    QgsUnitTypes::DistanceUnit lengthUnits() const;

    QgsUnitTypes::AreaUnit areaUnits() const;

    double measurePolygon( const QVector<QgsPointXY> &points ) const;

    double bearing( const QgsPointXY &p1, const QgsPointXY &p2 ) const;

    static QString formatDistance( double distance, int decimals, QgsUnitTypes::DistanceUnit unit, bool keepBaseUnit = false );

    static QString formatArea( double area, int decimals, QgsUnitTypes::AreaUnit unit, bool keepBaseUnit = false );

    double convertLengthMeasurement( double length, QgsUnitTypes::DistanceUnit toUnits ) const;

    double convertAreaMeasurement( double area, QgsUnitTypes::AreaUnit toUnits ) const;

    QgsPointXY computeSpheroidProject( const QgsPointXY &p1, double distance = 1, double azimuth = M_PI_2 ) const;

  private:

    double computeDistanceBearing( const QgsPointXY &p1, const QgsPointXY &p2,
                                   double *course1 = nullptr, double *course2 = nullptr ) const;

    double computePolygonArea( const QVector<QgsPointXY> &points ) const;

    double computePolygonFlatArea( const QVector<QgsPointXY> &points ) const;

    void computeAreaInit();

    void setFromParams( const QgsEllipsoidUtils::EllipsoidParameters &params );

    enum MeasureType
    {
      Default,
      Area,
      Length
    };

    QgsCoordinateTransform mCoordTransform;

    QString mEllipsoid;

    double mSemiMajor, mSemiMinor, mInvFlattening;

    // utility functions for polygon area measurement

    double getQ( double x ) const;
    double getQbar( double x ) const;

    double measure( const QgsAbstractGeometry *geomV2, MeasureType type = Default ) const;
    double measureLine( const QgsCurve *curve ) const;
    double measurePolygon( const QgsCurve *curve ) const;

    // temporary area measurement stuff

    double m_QA, m_QB, m_QC;
    double m_QbarA, m_QbarB, m_QbarC, m_QbarD;
    double m_AE;  /* a^2(1-e^2) */
    double m_Qp;  /* Q at the north pole */
    double m_E;   /* area of the earth */
    double m_TwoPI;

};

#endif