General purpose distance and area calculator. More...

#include <qgsdistancearea.h>

Public Member Functions
	QgsDistanceArea ()
	Constructor.
	QgsDistanceArea (const QgsDistanceArea &origDA)
	Copy constructor.
	~QgsDistanceArea ()
	Destructor.
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.
const QString &	ellipsoid () const
	returns ellipsoid's acronym
bool	ellipsoidalEnabled () const
	returns projections enabled flag
double	ellipsoidInverseFlattening () const
	returns ellipsoid's inverse flattening
double	ellipsoidSemiMajor () const
	returns ellipsoid's semi major axis
double	ellipsoidSemiMinor () const
	returns ellipsoid's semi minor axis
bool	geographic () const
	What sort of coordinate system is being used?
double	measure (QgsGeometry *geometry)
	general measurement (line distance or polygon area)
double	measureLine (const QList< QgsPoint > &points)
	measures line
double	measureLine (const QgsPoint &p1, const QgsPoint &p2)
	measures line with one segment
double	measurePerimeter (QgsGeometry *geometry)
	measures perimeter of polygon
double	measurePolygon (const QList< QgsPoint > &points)
	measures polygon area
QgsDistanceArea &	operator= (const QgsDistanceArea &origDA)
	Assignment operator.
bool	setEllipsoid (const QString &ellipsoid)
	sets ellipsoid by its acronym
bool	setEllipsoid (double semiMajor, double semiMinor)
	Sets ellipsoid by supplied radii.
void	setEllipsoidalMode (bool flag)
	sets whether coordinates must be projected to ellipsoid before measuring
void	setSourceAuthId (QString authid)
	sets source spatial reference system by authid
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)
long	sourceCrs () const
	returns source spatial reference system

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

Protected Member Functions
void	computeAreaInit ()
	precalculates some values (must be called always when changing ellipsoid)
double	computeDistance (const QList< QgsPoint > &points)
	calculate distance with given coordinates (does not do a transform anymore)
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	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)
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

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

Definition at line 34 of file qgsdistancearea.h.

Constructor & Destructor Documentation

QgsDistanceArea::QgsDistanceArea ( )

Constructor.

Definition at line 41 of file qgsdistancearea.cpp.

QgsDistanceArea::~QgsDistanceArea ( )

Destructor.

Definition at line 57 of file qgsdistancearea.cpp.

QgsDistanceArea::QgsDistanceArea ( const QgsDistanceArea & origDA )

Copy constructor.

Definition at line 52 of file qgsdistancearea.cpp.

Member Function Documentation

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

compute bearing - in radians

Definition at line 619 of file qgsdistancearea.cpp.

void QgsDistanceArea::computeAreaInit ( )

protected

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

Definition at line 792 of file qgsdistancearea.cpp.

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

protected

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

Definition at line 726 of file qgsdistancearea.cpp.

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 644 of file qgsdistancearea.cpp.

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

protected

uses flat / planimetric / Euclidean distance

Definition at line 721 of file qgsdistancearea.cpp.

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 827 of file qgsdistancearea.cpp.

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

protected

Definition at line 884 of file qgsdistancearea.cpp.

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

Helper for conversion between physical units.

Definition at line 1034 of file qgsdistancearea.cpp.

const QString& QgsDistanceArea::ellipsoid ( ) const

inline

returns ellipsoid's acronym

Definition at line 80 of file qgsdistancearea.h.

bool QgsDistanceArea::ellipsoidalEnabled ( ) const

inline

returns projections enabled flag

Definition at line 53 of file qgsdistancearea.h.

double QgsDistanceArea::ellipsoidInverseFlattening ( ) const

inline

returns ellipsoid's inverse flattening

Definition at line 87 of file qgsdistancearea.h.

double QgsDistanceArea::ellipsoidSemiMajor ( ) const

inline

returns ellipsoid's semi major axis

Definition at line 83 of file qgsdistancearea.h.

double QgsDistanceArea::ellipsoidSemiMinor ( ) const

inline

returns ellipsoid's semi minor axis

Definition at line 85 of file qgsdistancearea.h.

bool QgsDistanceArea::geographic ( ) const

inline

What sort of coordinate system is being used?

Definition at line 70 of file qgsdistancearea.h.

double QgsDistanceArea::measure ( QgsGeometry * geometry )

general measurement (line distance or polygon area)

Definition at line 257 of file qgsdistancearea.cpp.

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

measures line

Definition at line 419 of file qgsdistancearea.cpp.

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

measures line with one segment

Definition at line 461 of file qgsdistancearea.cpp.

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 392 of file qgsdistancearea.cpp.

double QgsDistanceArea::measurePerimeter ( QgsGeometry * geometry )

measures perimeter of polygon

Definition at line 332 of file qgsdistancearea.cpp.

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

measures polygon area

Definition at line 592 of file qgsdistancearea.cpp.

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 497 of file qgsdistancearea.cpp.

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

Assignment operator.

Definition at line 63 of file qgsdistancearea.cpp.

bool QgsDistanceArea::setEllipsoid ( const QString & ellipsoid )

sets ellipsoid by its acronym

Definition at line 112 of file qgsdistancearea.cpp.

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

Sets ellipsoid by supplied radii.

Definition at line 245 of file qgsdistancearea.cpp.

void QgsDistanceArea::setEllipsoidalMode ( bool flag )

sets whether coordinates must be projected to ellipsoid before measuring

Definition at line 88 of file qgsdistancearea.cpp.

void QgsDistanceArea::setSourceAuthId ( QString authid )

sets source spatial reference system by authid

Definition at line 105 of file qgsdistancearea.cpp.

void QgsDistanceArea::setSourceCrs ( long srsid )

sets source spatial reference system (by QGIS CRS)

Definition at line 93 of file qgsdistancearea.cpp.

void QgsDistanceArea::setSourceCrs ( const QgsCoordinateReferenceSystem & srcCRS )

Sets source spatial reference system (by QGIS CRS)

Note: : missing in Python bindings in QGIS < 2.2

Definition at line 100 of file qgsdistancearea.cpp.

long QgsDistanceArea::sourceCrs ( ) const

inline

returns source spatial reference system

Definition at line 68 of file qgsdistancearea.h.

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

static

Definition at line 905 of file qgsdistancearea.cpp.

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

/tmp/buildd/qgis-2.8.2+12wheezy/src/core/qgsdistancearea.h
/tmp/buildd/qgis-2.8.2+12wheezy/src/core/qgsdistancearea.cpp

Public Member Functions

Static Public Member Functions

Protected Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation