General purpose distance and area calculator. More...

#include <qgsdistancearea.h>

Public Member Functions
	QgsDistanceArea ()
	Constructor.
	~QgsDistanceArea ()
	Destructor.
	QgsDistanceArea (const QgsDistanceArea &origDA)
	Copy constructor.
QgsDistanceArea &	operator= (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	setSourceCrs (const QgsCoordinateReferenceSystem &srcCRS)
	Sets source spatial reference system (by QGIS CRS)
void	setSourceAuthId (QString authid)
	sets source spatial reference system by authid
long	sourceCrs () const
	returns source spatial reference system
bool	geographic () const
	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 () const
	returns ellipsoid's acronym
double	ellipsoidSemiMajor () const
	returns ellipsoid's semi major axis
double	ellipsoidSemiMinor () const
	returns ellipsoid's semi minor axis
double	ellipsoidInverseFlattening () const
	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	computeDistanceFlat (const QgsPoint &p1, const QgsPoint &p2)
	uses flat / planimetric / Euclidean distance
double	computeDistance (const QList< QgsPoint > &points)
	calculate distance with given coordinates (does not do a transform anymore)
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)

Detailed Description

General purpose distance and area calculator.

calculations are done on ellipsoid
it's possible to pass points/features in any CRS, coordinates are transformed
two options how to use it
- use measure() takes QgsGeometry as a parameter and calculates distance or area
- use directly measureLine(), measurePolygon() which take list of QgsPoints (both cases transform the coordinates from source CRS to the ellipse coords)
returned values are in meters resp. square meters

Constructor & Destructor Documentation

QgsDistanceArea::QgsDistanceArea ( )

Constructor.

QgsDistanceArea::~QgsDistanceArea ( )

Destructor.

QgsDistanceArea::QgsDistanceArea ( const QgsDistanceArea & origDA )

Copy constructor.

Member Function Documentation

double QgsDistanceArea::bearing	(	const QgsPoint &	p1,
		const QgsPoint &	p2
	)

compute bearing - in radians

void QgsDistanceArea::computeAreaInit ( )

protected

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

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

protected

calculate distance with given coordinates (does not do a transform anymore)

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

double QgsDistanceArea::computeDistanceFlat	(	const QgsPoint &	p1,
		const QgsPoint &	p2
	)

protected

uses flat / planimetric / Euclidean distance

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

protected

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

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

protected

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

Helper for conversion between physical units.

const QString& QgsDistanceArea::ellipsoid ( ) const

inline

returns ellipsoid's acronym

bool QgsDistanceArea::ellipsoidalEnabled ( ) const

inline

returns projections enabled flag

double QgsDistanceArea::ellipsoidInverseFlattening ( ) const

inline

returns ellipsoid's inverse flattening

double QgsDistanceArea::ellipsoidSemiMajor ( ) const

inline

returns ellipsoid's semi major axis

double QgsDistanceArea::ellipsoidSemiMinor ( ) const

inline

returns ellipsoid's semi minor axis

bool QgsDistanceArea::geographic ( ) const

inline

What sort of coordinate system is being used?

double QgsDistanceArea::measure ( QgsGeometry * geometry )

general measurement (line distance or polygon area)

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

measures line

double QgsDistanceArea::measureLine	(	const QgsPoint &	p1,
		const QgsPoint &	p2
	)

measures line with one segment

const unsigned char * QgsDistanceArea::measureLine	(	const unsigned char *	feature,
		double *	area,
		bool	hasZptr = `false`
	)

protected

measures line distance, line points are extracted from WKB

double QgsDistanceArea::measurePerimeter ( QgsGeometry * geometry )

measures perimeter of polygon

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

measures polygon area

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

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

Assignment operator.

bool QgsDistanceArea::setEllipsoid ( const QString & ellipsoid )

sets ellipsoid by its acronym

bool QgsDistanceArea::setEllipsoid	(	double	semiMajor,
		double	semiMinor
	)

Sets ellipsoid by supplied radii.

void QgsDistanceArea::setEllipsoidalMode ( bool flag )

sets whether coordinates must be projected to ellipsoid before measuring

void QgsDistanceArea::setSourceAuthId ( QString authid )

sets source spatial reference system by authid

void QgsDistanceArea::setSourceCrs ( long srsid )

sets source spatial reference system (by QGIS CRS)

void QgsDistanceArea::setSourceCrs ( const QgsCoordinateReferenceSystem & srcCRS )

Sets source spatial reference system (by QGIS CRS)

Note: : missing in Python bindings in QGIS < 2.2

long QgsDistanceArea::sourceCrs ( ) const

inline

returns source spatial reference system

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

static

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

/tmp/buildd/qgis-2.6.0+wheezy1/src/core/qgsdistancearea.h
/tmp/buildd/qgis-2.6.0+wheezy1/src/core/qgsdistancearea.cpp

Public Member Functions

Static Public Member Functions

Protected Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation