QGIS API Documentation  2.0.1-Dufour
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Properties Friends Macros Groups Pages
Public Member Functions | Static Public Member Functions | Protected Member Functions | Private Member Functions | Private Attributes | List of all members
QgsDistanceArea Class Reference

General purpose distance and area calculator. More...

#include <qgsdistancearea.h>

Collaboration diagram for QgsDistanceArea:
Collaboration graph
[legend]

Public Member Functions

 QgsDistanceArea ()
 Constructor.
 ~QgsDistanceArea ()
 Destructor.
 QgsDistanceArea (const QgsDistanceArea &origDA)
 Copy constructor.
QgsDistanceAreaoperator= (const QgsDistanceArea &origDA)
 Assignment operator.
void setEllipsoidalMode (bool flag)
 sets whether coordinates must be projected to ellipsoid before measuring
bool ellipsoidalEnabled () const
 returns projections enabled flag
void setSourceCrs (long srsid)
 sets source spatial reference system (by QGIS CRS)
void setSourceAuthId (QString authid)
 sets source spatial reference system by authid
long sourceCrs ()
 returns source spatial reference system
bool geographic ()
 What sort of coordinate system is being used?
bool setEllipsoid (const QString &ellipsoid)
 sets ellipsoid by its acronym
bool setEllipsoid (double semiMajor, double semiMinor)
 Sets ellipsoid by supplied radii.
const QString & ellipsoid ()
 returns ellipsoid's acronym
double ellipsoidSemiMajor ()
 returns ellipsoid's semi major axis
double ellipsoidSemiMinor ()
 returns ellipsoid's semi minor axis
double ellipsoidInverseFlattening ()
 returns ellipsoid's inverse flattening
double measure (QgsGeometry *geometry)
 general measurement (line distance or polygon area)
double measurePerimeter (QgsGeometry *geometry)
 measures perimeter of polygon
double measureLine (const QList< QgsPoint > &points)
 measures line
double measureLine (const QgsPoint &p1, const QgsPoint &p2)
 measures line with one segment
double measurePolygon (const QList< QgsPoint > &points)
 measures polygon area
double bearing (const QgsPoint &p1, const QgsPoint &p2)
 compute bearing - in radians
void convertMeasurement (double &measure, QGis::UnitType &measureUnits, QGis::UnitType displayUnits, bool isArea)
 Helper for conversion between physical units.

Static Public Member Functions

static QString textUnit (double value, int decimals, QGis::UnitType u, bool isArea, bool keepBaseUnit=false)

Protected Member Functions

const unsigned char * measureLine (const unsigned char *feature, double *area, bool hasZptr=false)
 measures line distance, line points are extracted from WKB
const unsigned char * measurePolygon (const unsigned char *feature, double *area, double *perimeter, bool hasZptr=false)
 measures polygon area and perimeter, vertices are extracted from WKB
double computeDistanceBearing (const QgsPoint &p1, const QgsPoint &p2, double *course1=NULL, double *course2=NULL)
 calculates distance from two points on ellipsoid based on inverse Vincenty's formulae
double computePolygonArea (const QList< QgsPoint > &points)
 calculates area of polygon on ellipsoid algorithm has been taken from GRASS: gis/area_poly1.c
double computePolygonFlatArea (const QList< QgsPoint > &points)
void computeAreaInit ()
 precalculates some values (must be called always when changing ellipsoid)

Private Member Functions

void _copy (const QgsDistanceArea &origDA)
 Copy helper.
double getQ (double x)
double getQbar (double x)

Private Attributes

QgsCoordinateTransformmCoordTransform
 used for transforming coordinates from source CRS to ellipsoid's coordinates
bool mEllipsoidalMode
 indicates whether we will transform coordinates
long mSourceRefSys
 id of the source spatial reference system
QString mEllipsoid
 ellipsoid acronym (from table tbl_ellipsoids)
double mSemiMajor
 ellipsoid parameters
double mSemiMinor
double mInvFlattening
double m_QA
double m_QB
double m_QC
double m_QbarA
double m_QbarB
double m_QbarC
double m_QbarD
double m_AE
double m_Qp
double m_E
double m_TwoPI

Detailed Description

General purpose distance and area calculator.

Definition at line 34 of file qgsdistancearea.h.

Constructor & Destructor Documentation

QgsDistanceArea::QgsDistanceArea ( )

Constructor.

Definition at line 41 of file qgsdistancearea.cpp.

References GEO_NONE, GEOCRS_ID, mCoordTransform, mEllipsoidalMode, setEllipsoid(), and setSourceCrs().

QgsDistanceArea::~QgsDistanceArea ( )

Destructor.

Definition at line 57 of file qgsdistancearea.cpp.

References mCoordTransform.

QgsDistanceArea::QgsDistanceArea ( const QgsDistanceArea origDA)

Copy constructor.

Definition at line 52 of file qgsdistancearea.cpp.

References _copy().

Member Function Documentation

void QgsDistanceArea::_copy ( const QgsDistanceArea origDA)
private
double QgsDistanceArea::bearing ( const QgsPoint p1,
const QgsPoint p2 
)
void QgsDistanceArea::computeAreaInit ( )
protected

precalculates some values (must be called always when changing ellipsoid)

Definition at line 749 of file qgsdistancearea.cpp.

References getQ(), m_AE, m_E, M_PI, m_QA, m_QB, m_QbarA, m_QbarB, m_QbarC, m_QbarD, m_QC, m_Qp, m_TwoPI, mSemiMajor, and mSemiMinor.

Referenced by _copy(), and setEllipsoid().

double QgsDistanceArea::computeDistanceBearing ( const QgsPoint p1,
const QgsPoint p2,
double *  course1 = NULL,
double *  course2 = NULL 
)
protected

calculates distance from two points on ellipsoid based on inverse Vincenty's formulae

Points p1 and p2 are expected to be in degrees and in currently used ellipsoid

Note
if course1 is not NULL, bearing (in radians) from first point is calculated (the same for course2)
Returns
distance in meters

Definition at line 643 of file qgsdistancearea.cpp.

References DEG2RAD, M_PI, mInvFlattening, mSemiMajor, mSemiMinor, QgsPoint::x(), and QgsPoint::y().

Referenced by bearing(), and measureLine().

double QgsDistanceArea::computePolygonArea ( const QList< QgsPoint > &  points)
protected

calculates area of polygon on ellipsoid algorithm has been taken from GRASS: gis/area_poly1.c

Definition at line 778 of file qgsdistancearea.cpp.

References computePolygonFlatArea(), DEG2RAD, GEO_NONE, getQ(), getQbar(), m_AE, m_E, M_PI, m_Qp, m_TwoPI, mEllipsoid, mEllipsoidalMode, and QgsDebugMsgLevel.

Referenced by measurePolygon().

double QgsDistanceArea::computePolygonFlatArea ( const QList< QgsPoint > &  points)
protected

Definition at line 835 of file qgsdistancearea.cpp.

References size.

Referenced by computePolygonArea().

void QgsDistanceArea::convertMeasurement ( double &  measure,
QGis::UnitType measureUnits,
QGis::UnitType  displayUnits,
bool  isArea 
)

Helper for conversion between physical units.

Definition at line 975 of file qgsdistancearea.cpp.

References QGis::Degrees, QGis::Feet, GEO_NONE, mEllipsoid, mEllipsoidalMode, QGis::Meters, and QgsDebugMsg.

Referenced by QgsMapToolIdentify::convertMeasurement().

const QString& QgsDistanceArea::ellipsoid ( )
inline

returns ellipsoid's acronym

Definition at line 74 of file qgsdistancearea.h.

Referenced by setEllipsoid(), and QgsExpression::setGeomCalculator().

bool QgsDistanceArea::ellipsoidalEnabled ( ) const
inline

returns projections enabled flag

Definition at line 53 of file qgsdistancearea.h.

Referenced by QgsExpression::setGeomCalculator().

double QgsDistanceArea::ellipsoidInverseFlattening ( )
inline

returns ellipsoid's inverse flattening

Definition at line 81 of file qgsdistancearea.h.

double QgsDistanceArea::ellipsoidSemiMajor ( )
inline

returns ellipsoid's semi major axis

Definition at line 77 of file qgsdistancearea.h.

double QgsDistanceArea::ellipsoidSemiMinor ( )
inline

returns ellipsoid's semi minor axis

Definition at line 79 of file qgsdistancearea.h.

bool QgsDistanceArea::geographic ( )
inline

What sort of coordinate system is being used?

Definition at line 64 of file qgsdistancearea.h.

double QgsDistanceArea::getQ ( double  x)
private

Definition at line 727 of file qgsdistancearea.cpp.

References m_QA, m_QB, and m_QC.

Referenced by computeAreaInit(), and computePolygonArea().

double QgsDistanceArea::getQbar ( double  x)
private

Definition at line 738 of file qgsdistancearea.cpp.

References m_QbarA, m_QbarB, m_QbarC, and m_QbarD.

Referenced by computePolygonArea().

double QgsDistanceArea::measure ( QgsGeometry geometry)
double QgsDistanceArea::measureLine ( const QList< QgsPoint > &  points)
double QgsDistanceArea::measureLine ( const QgsPoint p1,
const QgsPoint p2 
)
const unsigned char * QgsDistanceArea::measureLine ( const unsigned char *  feature,
double *  area,
bool  hasZptr = false 
)
protected

measures line distance, line points are extracted from WKB

Definition at line 386 of file qgsdistancearea.cpp.

References measureLine(), and QgsDebugMsg.

double QgsDistanceArea::measurePerimeter ( QgsGeometry geometry)
double QgsDistanceArea::measurePolygon ( const QList< QgsPoint > &  points)
const unsigned char * QgsDistanceArea::measurePolygon ( const unsigned char *  feature,
double *  area,
double *  perimeter,
bool  hasZptr = false 
)
protected

measures polygon area and perimeter, vertices are extracted from WKB

Definition at line 494 of file qgsdistancearea.cpp.

References computePolygonArea(), GEO_NONE, QgsMessageLog::logMessage(), mCoordTransform, measureLine(), mEllipsoid, mEllipsoidalMode, QgsDebugMsg, tr, and QgsCoordinateTransform::transform().

QgsDistanceArea & QgsDistanceArea::operator= ( const QgsDistanceArea origDA)

Assignment operator.

Definition at line 63 of file qgsdistancearea.cpp.

References _copy().

bool QgsDistanceArea::setEllipsoid ( const QString &  ellipsoid)
bool QgsDistanceArea::setEllipsoid ( double  semiMajor,
double  semiMinor 
)

Sets ellipsoid by supplied radii.

Definition at line 241 of file qgsdistancearea.cpp.

References computeAreaInit(), mEllipsoid, mInvFlattening, mSemiMajor, and mSemiMinor.

void QgsDistanceArea::setEllipsoidalMode ( bool  flag)
void QgsDistanceArea::setSourceAuthId ( QString  authid)

sets source spatial reference system by authid

Definition at line 101 of file qgsdistancearea.cpp.

References QgsCoordinateReferenceSystem::createFromOgcWmsCrs(), mCoordTransform, and QgsCoordinateTransform::setSourceCrs().

void QgsDistanceArea::setSourceCrs ( long  srsid)
long QgsDistanceArea::sourceCrs ( )
inline

returns source spatial reference system

Definition at line 62 of file qgsdistancearea.h.

Referenced by QgsExpression::setGeomCalculator().

QString QgsDistanceArea::textUnit ( double  value,
int  decimals,
QGis::UnitType  u,
bool  isArea,
bool  keepBaseUnit = false 
)
static

Member Data Documentation

double QgsDistanceArea::m_AE
private

Definition at line 169 of file qgsdistancearea.h.

Referenced by computeAreaInit(), and computePolygonArea().

double QgsDistanceArea::m_E
private

Definition at line 171 of file qgsdistancearea.h.

Referenced by computeAreaInit(), and computePolygonArea().

double QgsDistanceArea::m_QA
private

Definition at line 167 of file qgsdistancearea.h.

Referenced by computeAreaInit(), and getQ().

double QgsDistanceArea::m_QB
private

Definition at line 167 of file qgsdistancearea.h.

Referenced by computeAreaInit(), and getQ().

double QgsDistanceArea::m_QbarA
private

Definition at line 168 of file qgsdistancearea.h.

Referenced by computeAreaInit(), and getQbar().

double QgsDistanceArea::m_QbarB
private

Definition at line 168 of file qgsdistancearea.h.

Referenced by computeAreaInit(), and getQbar().

double QgsDistanceArea::m_QbarC
private

Definition at line 168 of file qgsdistancearea.h.

Referenced by computeAreaInit(), and getQbar().

double QgsDistanceArea::m_QbarD
private

Definition at line 168 of file qgsdistancearea.h.

Referenced by computeAreaInit(), and getQbar().

double QgsDistanceArea::m_QC
private

Definition at line 167 of file qgsdistancearea.h.

Referenced by computeAreaInit(), and getQ().

double QgsDistanceArea::m_Qp
private

Definition at line 170 of file qgsdistancearea.h.

Referenced by computeAreaInit(), and computePolygonArea().

double QgsDistanceArea::m_TwoPI
private

Definition at line 172 of file qgsdistancearea.h.

Referenced by computeAreaInit(), and computePolygonArea().

QgsCoordinateTransform* QgsDistanceArea::mCoordTransform
private

used for transforming coordinates from source CRS to ellipsoid's coordinates

Definition at line 146 of file qgsdistancearea.h.

Referenced by _copy(), bearing(), measureLine(), measurePolygon(), QgsDistanceArea(), setEllipsoid(), setSourceAuthId(), setSourceCrs(), and ~QgsDistanceArea().

QString QgsDistanceArea::mEllipsoid
private

ellipsoid acronym (from table tbl_ellipsoids)

Definition at line 155 of file qgsdistancearea.h.

Referenced by _copy(), bearing(), computePolygonArea(), convertMeasurement(), measureLine(), measurePolygon(), and setEllipsoid().

bool QgsDistanceArea::mEllipsoidalMode
private

indicates whether we will transform coordinates

Definition at line 149 of file qgsdistancearea.h.

Referenced by _copy(), bearing(), computePolygonArea(), convertMeasurement(), measureLine(), measurePolygon(), QgsDistanceArea(), and setEllipsoidalMode().

double QgsDistanceArea::mInvFlattening
private

Definition at line 158 of file qgsdistancearea.h.

Referenced by _copy(), computeDistanceBearing(), and setEllipsoid().

double QgsDistanceArea::mSemiMajor
private

ellipsoid parameters

Definition at line 158 of file qgsdistancearea.h.

Referenced by _copy(), computeAreaInit(), computeDistanceBearing(), and setEllipsoid().

double QgsDistanceArea::mSemiMinor
private

Definition at line 158 of file qgsdistancearea.h.

Referenced by _copy(), computeAreaInit(), computeDistanceBearing(), and setEllipsoid().

long QgsDistanceArea::mSourceRefSys
private

id of the source spatial reference system

Definition at line 152 of file qgsdistancearea.h.

Referenced by _copy().


The documentation for this class was generated from the following files: