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qgsdistancearea.h
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1 /***************************************************************************
2  qgsdistancearea.h - Distance and area calculations on the ellipsoid
3  ---------------------------------------------------------------------------
4  Date : September 2005
5  Copyright : (C) 2005 by Martin Dobias
6  email : won.der at centrum.sk
7  ***************************************************************************
8  * *
9  * This program is free software; you can redistribute it and/or modify *
10  * it under the terms of the GNU General Public License as published by *
11  * the Free Software Foundation; either version 2 of the License, or *
12  * (at your option) any later version. *
13  * *
14  ***************************************************************************/
15 
16 #ifndef QGSDISTANCEAREA_H
17 #define QGSDISTANCEAREA_H
18 
19 #include <QList>
20 #include "qgscoordinatetransform.h"
21 
22 class QgsGeometry;
23 
34 class CORE_EXPORT QgsDistanceArea
35 {
36  public:
39 
41  ~QgsDistanceArea();
42 
44  QgsDistanceArea( const QgsDistanceArea &origDA );
45 
47  QgsDistanceArea & operator=( const QgsDistanceArea & origDA );
48 
50  void setEllipsoidalMode( bool flag );
51 
53  bool ellipsoidalEnabled() const { return mEllipsoidalMode; }
54 
56  void setSourceCrs( long srsid );
57 
62  void setSourceCrs( const QgsCoordinateReferenceSystem& srcCRS );
63 
65  void setSourceAuthId( QString authid );
66 
68  long sourceCrs() const { return mSourceRefSys; }
70  bool geographic() const { return mCoordTransform->sourceCrs().geographicFlag(); }
71 
73  bool setEllipsoid( const QString& ellipsoid );
74 
76  // Inverse flattening is calculated with invf = a/(a-b)
77  bool setEllipsoid( double semiMajor, double semiMinor );
78 
80  const QString& ellipsoid() const { return mEllipsoid; }
81 
83  double ellipsoidSemiMajor() const { return mSemiMajor; }
85  double ellipsoidSemiMinor() const { return mSemiMinor; }
87  double ellipsoidInverseFlattening() const { return mInvFlattening; }
88 
90  double measure( QgsGeometry* geometry );
91 
93  double measurePerimeter( QgsGeometry* geometry );
94 
96  double measureLine( const QList<QgsPoint>& points );
97 
99  double measureLine( const QgsPoint& p1, const QgsPoint& p2 );
100 
102  double measurePolygon( const QList<QgsPoint>& points );
103 
105  double bearing( const QgsPoint& p1, const QgsPoint& p2 );
106 
107  static QString textUnit( double value, int decimals, QGis::UnitType u, bool isArea, bool keepBaseUnit = false );
108 
110  void convertMeasurement( double &measure, QGis::UnitType &measureUnits, QGis::UnitType displayUnits, bool isArea );
111 
112  protected:
114  const unsigned char* measureLine( const unsigned char* feature, double* area, bool hasZptr = false );
116  const unsigned char* measurePolygon( const unsigned char* feature, double* area, double* perimeter, bool hasZptr = false );
117 
128  double computeDistanceBearing( const QgsPoint& p1, const QgsPoint& p2,
129  double* course1 = NULL, double* course2 = NULL );
130 
131 
137  double computePolygonArea( const QList<QgsPoint>& points );
138 
139  double computePolygonFlatArea( const QList<QgsPoint>& points );
140 
145  void computeAreaInit();
146 
147  private:
149  void _copy( const QgsDistanceArea & origDA );
150 
153 
156 
159 
161  QString mEllipsoid;
162 
164  double mSemiMajor, mSemiMinor, mInvFlattening;
165 
166  // utility functions for polygon area measurement
167 
168  double getQ( double x );
169  double getQbar( double x );
170 
171  // temporary area measurement stuff
172 
173  double m_QA, m_QB, m_QC;
174  double m_QbarA, m_QbarB, m_QbarC, m_QbarD;
175  double m_AE; /* a^2(1-e^2) */
176  double m_Qp; /* Q at the north pole */
177  double m_E; /* area of the earth */
178  double m_TwoPI;
179 
180 };
181 
182 #endif