General purpose distance and area calculator. More...

#include <qgsdistancearea.h>

Collaboration diagram for QgsDistanceArea:

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	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
QgsCoordinateTransform *	mCoordTransform
	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.

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.

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

Copy helper.

Copy helper. Avoid Sqlite3 accesses.

Definition at line 75 of file qgsdistancearea.cpp.

References computeAreaInit(), QgsCoordinateTransform::destCRS(), mCoordTransform, mEllipsoid, mEllipsoidalMode, mInvFlattening, mSemiMajor, mSemiMinor, mSourceRefSys, and QgsCoordinateTransform::sourceCrs().

Referenced by operator=(), and QgsDistanceArea().

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

compute bearing - in radians

Definition at line 618 of file qgsdistancearea.cpp.

References computeDistanceBearing(), GEO_NONE, mCoordTransform, mEllipsoid, mEllipsoidalMode, QgsCoordinateTransform::transform(), QgsPoint::x(), and QgsPoint::y().

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 )

general measurement (line distance or polygon area)

Definition at line 255 of file qgsdistancearea.cpp.

References QgsGeometry::asWkb(), measureLine(), measurePolygon(), QgsDebugMsg, QGis::WKBLineString, QGis::WKBLineString25D, QGis::WKBMultiLineString, QGis::WKBMultiLineString25D, QGis::WKBMultiPolygon, QGis::WKBMultiPolygon25D, QGis::WKBPolygon, and QGis::WKBPolygon25D.

Referenced by fcnGeomArea(), fcnGeomLength(), QgsMapToolIdentify::featureDerivedAttributes(), QgsGeometryAnalyzer::perimeterMeasure(), and QgsGeometryAnalyzer::simpleMeasure().

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

measures line

Definition at line 416 of file qgsdistancearea.cpp.

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

Referenced by QgsComposerScaleBar::mapWidth(), measure(), measureLine(), and measurePolygon().

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

measures line with one segment

Definition at line 458 of file qgsdistancearea.cpp.

References computeDistanceBearing(), QgsCoordinateTransform::destCRS(), GEO_NONE, QgsMessageLog::logMessage(), mCoordTransform, mEllipsoid, mEllipsoidalMode, QgsDebugMsgLevel, QgsCoordinateTransform::sourceCrs(), QgsCoordinateReferenceSystem::toProj4(), QgsPoint::toString(), tr, QgsCoordinateTransform::transform(), QgsPoint::x(), and QgsPoint::y().

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 )

measures perimeter of polygon

Definition at line 327 of file qgsdistancearea.cpp.

References QgsGeometry::asWkb(), measurePolygon(), QgsDebugMsg, QGis::WKBLineString, QGis::WKBLineString25D, QGis::WKBMultiLineString, QGis::WKBMultiLineString25D, QGis::WKBMultiPolygon, QGis::WKBMultiPolygon25D, QGis::WKBPolygon, and QGis::WKBPolygon25D.

Referenced by fcnGeomPerimeter(), and QgsMapToolIdentify::featureDerivedAttributes().

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

measures polygon area

Definition at line 591 of file qgsdistancearea.cpp.

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

Referenced by measure(), and measurePerimeter().

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 )

sets whether coordinates must be projected to ellipsoid before measuring

Definition at line 89 of file qgsdistancearea.cpp.

References mEllipsoidalMode.

Referenced by QgsMapToolIdentify::featureDerivedAttributes(), QgsExpression::initGeomCalculator(), QgsComposerScaleBar::mapWidth(), QgsAttributeDialog::QgsAttributeDialog(), QgsExpression::setGeomCalculator(), and QgsMapRenderer::setProjectionsEnabled().

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 )

sets source spatial reference system (by QGIS CRS)

Definition at line 94 of file qgsdistancearea.cpp.

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

Referenced by QgsMapToolIdentify::featureDerivedAttributes(), QgsComposerScaleBar::mapWidth(), QgsAttributeDialog::QgsAttributeDialog(), QgsDistanceArea(), QgsMapRenderer::setDestinationCrs(), and QgsExpression::setGeomCalculator().

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

Definition at line 856 of file qgsdistancearea.cpp.

References QGis::Degrees, QGis::Feet, QGis::Meters, QgsDebugMsg, tr, and QGis::UnknownUnit.

Referenced by QgsMapToolIdentify::featureDerivedAttributes().

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:

/tmp/buildd/qgis-2.0.1/src/core/qgsdistancearea.h
/tmp/buildd/qgis-2.0.1/src/core/qgsdistancearea.cpp

Public Member Functions

Static Public Member Functions

Protected Member Functions

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation