Class for doing transforms between two map coordinate systems. More...

#include <qgscoordinatetransform.h>

Collaboration diagram for QgsCoordinateTransform:

Public Types
enum	TransformDirection { ForwardTransform, ReverseTransform }
	Enum used to indicate the direction (forward or inverse) of the transform. More...

Public Slots
void	initialise ()
	initialise is used to actually create the Transformer instance
bool	readXML (QDomNode &theNode)
bool	writeXML (QDomNode &theNode, QDomDocument &theDoc)

Signals
void	invalidTransformInput () const
	Signal when an invalid pj_transform() has occured.

Public Member Functions
	QgsCoordinateTransform ()
	QgsCoordinateTransform (const QgsCoordinateReferenceSystem &theSource, const QgsCoordinateReferenceSystem &theDest)
	Constructs a QgsCoordinateTransform using QgsCoordinateReferenceSystem objects.
	QgsCoordinateTransform (long theSourceSrsId, long theDestSrsId)
	Constructs a QgsCoordinateTransform using CRS ID of source and destination CRS.
	QgsCoordinateTransform (QString theSourceWkt, QString theDestWkt)
	QgsCoordinateTransform (long theSourceSrid, QString theDestWkt, QgsCoordinateReferenceSystem::CrsType theSourceCRSType=QgsCoordinateReferenceSystem::PostgisCrsId)
	~QgsCoordinateTransform ()
	destructor
QgsCoordinateTransform *	clone () const
void	setSourceCrs (const QgsCoordinateReferenceSystem &theCRS)
void	setDestCRS (const QgsCoordinateReferenceSystem &theCRS)
const QgsCoordinateReferenceSystem &	sourceCrs () const
const QgsCoordinateReferenceSystem &	destCRS () const
QgsPoint	transform (const QgsPoint p, TransformDirection direction=ForwardTransform) const
QgsPoint	transform (const double x, const double y, TransformDirection direction=ForwardTransform) const
QgsRectangle	transformBoundingBox (const QgsRectangle theRect, TransformDirection direction=ForwardTransform) const
void	transformInPlace (double &x, double &y, double &z, TransformDirection direction=ForwardTransform) const
void	transformInPlace (QVector< double > &x, QVector< double > &y, QVector< double > &z, TransformDirection direction=ForwardTransform) const
void	transformPolygon (QPolygonF &poly, TransformDirection direction=ForwardTransform) const
QgsRectangle	transform (const QgsRectangle theRect, TransformDirection direction=ForwardTransform) const
void	transformCoords (const int &numPoint, double x, double y, double *z, TransformDirection direction=ForwardTransform) const
bool	isInitialised () const
bool	isShortCircuited ()
void	setDestCRSID (long theCRSID)
int	sourceDatumTransform () const
void	setSourceDatumTransform (int dt)
int	destinationDatumTransform () const
void	setDestinationDatumTransform (int dt)

Static Public Member Functions
static QList< QList< int > >	datumTransformations (const QgsCoordinateReferenceSystem &srcCRS, const QgsCoordinateReferenceSystem &destCRS)
	Returns list of datum transformations for the given src and dest CRS.
static QString	datumTransformString (int datumTransform)
static bool	datumTransformCrsInfo (int datumTransform, int &epsgNr, QString &srcProjection, QString &dstProjection, QString &remarks, QString &scope, bool &preferred, bool &deprecated)
	Gets name of source and dest geographical CRS (to show in a tooltip)

Private Member Functions
void	setFinder ()
void	addNullGridShifts (QString &srcProjString, QString &destProjString)
	In certain situations, null grid shifts have to be added to src / dst proj string.

Static Private Member Functions
static QString	stripDatumTransform (const QString &proj4)
	Removes +nadgrids and +towgs84 from proj4 string.
static void	searchDatumTransform (const QString &sql, QList< int > &transforms)

Private Attributes
bool	mShortCircuit
bool	mInitialisedFlag
QgsCoordinateReferenceSystem	mSourceCRS
QgsCoordinateReferenceSystem	mDestCRS
projPJ	mSourceProjection
projPJ	mDestinationProjection
int	mSourceDatumTransform
int	mDestinationDatumTransform

Detailed Description

Class for doing transforms between two map coordinate systems.

This class can convert map coordinates to a different coordinate reference system. It is normally associated with a map layer and is used to transform between the layer's coordinate system and the coordinate system of the map canvas, although it can be used in a more general sense to transform coordinates.

All references to source and destination coordinate systems refer to layer and map canvas respectively. All operations are from the perspective of the layer. For example, a forward transformation transforms coordinates from the layers coordinate system to the map canvas.

Definition at line 52 of file qgscoordinatetransform.h.

Member Enumeration Documentation

enum QgsCoordinateTransform::TransformDirection

Enum used to indicate the direction (forward or inverse) of the transform.

Enumerator:

ForwardTransform	Transform from source to destination CRS.
ReverseTransform	Transform from destination to source CRS.

Definition at line 94 of file qgscoordinatetransform.h.

Constructor & Destructor Documentation

QgsCoordinateTransform::QgsCoordinateTransform ( )

Default constructor. Make sure you use initialised() manually if you use this one!

Definition at line 40 of file qgscoordinatetransform.cpp.

References setFinder().

Referenced by clone().

QgsCoordinateTransform::QgsCoordinateTransform	(	const QgsCoordinateReferenceSystem &	theSource,
		const QgsCoordinateReferenceSystem &	theDest
	)

Constructs a QgsCoordinateTransform using QgsCoordinateReferenceSystem objects.

Parameters

theSource	CRS, typically of the layer's coordinate system
theDest	CRS, typically of the map canvas coordinate system

Definition at line 51 of file qgscoordinatetransform.cpp.

References initialise(), mDestCRS, mSourceCRS, and setFinder().

QgsCoordinateTransform::QgsCoordinateTransform	(	long	theSourceSrsId,
		long	theDestSrsId
	)

Constructs a QgsCoordinateTransform using CRS ID of source and destination CRS.

Definition at line 65 of file qgscoordinatetransform.cpp.

References initialise().

QgsCoordinateTransform::QgsCoordinateTransform	(	QString	theSourceWkt,
		QString	theDestWkt
	)

Constructs a QgsCoordinateTransform using the Well Known Text representation of the layer and map canvas coordinate systems

Parameters

theSourceWkt	Wkt, typically of the layer's coordinate system
theDestWkt	Wkt, typically of the map canvas coordinate system

Definition at line 78 of file qgscoordinatetransform.cpp.

References QgsCoordinateReferenceSystem::createFromWkt(), initialise(), mDestCRS, mSourceCRS, and setFinder().

QgsCoordinateTransform::QgsCoordinateTransform	(	long	theSourceSrid,
		QString	theDestWkt,
		QgsCoordinateReferenceSystem::CrsType	theSourceCRSType = `QgsCoordinateReferenceSystem::PostgisCrsId`
	)

Constructs a QgsCoordinateTransform using a Spatial Reference Id of the layer and map canvas coordinate system as Wkt

Parameters

theSourceSrid	Spatial Ref Id of the layer's coordinate system
theDestWkt	Wkt of the map canvas coordinate system
theSourceCRSType	On of the enum members defined in QgsCoordinateReferenceSystem::CrsType

Definition at line 96 of file qgscoordinatetransform.cpp.

References QgsCoordinateReferenceSystem::createFromId(), QgsCoordinateReferenceSystem::createFromWkt(), initialise(), mDestCRS, mSourceCRS, and setFinder().

QgsCoordinateTransform::~QgsCoordinateTransform ( )

destructor

Definition at line 117 of file qgscoordinatetransform.cpp.

References mDestinationProjection, and mSourceProjection.

Member Function Documentation

void QgsCoordinateTransform::addNullGridShifts	(	QString &	srcProjString,
		QString &	destProjString
	)

private

In certain situations, null grid shifts have to be added to src / dst proj string.

Definition at line 987 of file qgscoordinatetransform.cpp.

References QgsCoordinateReferenceSystem::authid(), mDestCRS, mDestinationDatumTransform, mSourceCRS, and mSourceDatumTransform.

Referenced by initialise().

QgsCoordinateTransform * QgsCoordinateTransform::clone ( ) const

Definition at line 130 of file qgscoordinatetransform.cpp.

References destCRS(), destinationDatumTransform(), initialise(), QgsCoordinateTransform(), setDestinationDatumTransform(), setSourceDatumTransform(), sourceCrs(), sourceDatumTransform(), and tr.

Referenced by QgsPalLabeling::addDiagramLayer(), and QgsPalLabeling::prepareLayer().

QList< QList< int > > QgsCoordinateTransform::datumTransformations	(	const QgsCoordinateReferenceSystem &	srcCRS,
		const QgsCoordinateReferenceSystem &	destCRS
	)

static

Returns list of datum transformations for the given src and dest CRS.

Note: not available in python bindings

Definition at line 771 of file qgscoordinatetransform.cpp.

References QgsCoordinateReferenceSystem::geographicCRSAuthId(), and searchDatumTransform().

Referenced by QgsMapCanvas::getDatumTransformInfo().

bool QgsCoordinateTransform::datumTransformCrsInfo	(	int	datumTransform,
		int &	epsgNr,
		QString &	srcProjection,
		QString &	dstProjection,
		QString &	remarks,
		QString &	scope,
		bool &	preferred,
		bool &	deprecated
	)

static

Gets name of source and dest geographical CRS (to show in a tooltip)

Returns: epsgNr epsg code of the transformation (or 0 if not in epsg db)

Definition at line 940 of file qgscoordinatetransform.cpp.

References QgsCoordinateReferenceSystem::createFromOgcWmsCrs(), QgsCoordinateReferenceSystem::description(), and QgsApplication::srsDbFilePath().

Referenced by QgsDatumTransformDialog::load().

QString QgsCoordinateTransform::datumTransformString ( int datumTransform )

static

Definition at line 886 of file qgscoordinatetransform.cpp.

References QgsApplication::srsDbFilePath().

Referenced by initialise(), and QgsDatumTransformDialog::load().

const QgsCoordinateReferenceSystem& QgsCoordinateTransform::destCRS ( ) const

inline

Get the QgsCoordinateReferenceSystem representation of the map canvas coordinate system

Returns: QgsCoordinateReferenceSystem of the map canvas coordinate system

Definition at line 122 of file qgscoordinatetransform.h.

Referenced by QgsDistanceArea::_copy(), clone(), QgsVectorFileWriter::createSymbolLayerTable(), QgsRasterLayer::draw(), QgsVectorFileWriter::exportFeaturesSymbolLevels(), QgsDistanceArea::measureLine(), operator<<(), QgsMapRenderer::outputExtentToLayerExtent(), and QgsVectorFileWriter::writeAsVectorFormat().

int QgsCoordinateTransform::destinationDatumTransform ( ) const

inline

Definition at line 227 of file qgscoordinatetransform.h.

Referenced by clone(), and QgsRasterLayer::draw().

void QgsCoordinateTransform::initialise ( )

slot

initialise is used to actually create the Transformer instance

Definition at line 159 of file qgscoordinatetransform.cpp.

References addNullGridShifts(), QgsCoordinateReferenceSystem::authid(), QgsCRSCache::crsByAuthId(), datumTransformString(), QgsCRSCache::instance(), QgsCoordinateReferenceSystem::isValid(), mDestCRS, mDestinationDatumTransform, mDestinationProjection, mInitialisedFlag, mShortCircuit, mSourceCRS, mSourceDatumTransform, mSourceProjection, QgsDebugMsg, QgsDebugMsgLevel, stripDatumTransform(), and QgsCoordinateReferenceSystem::toProj4().

Referenced by clone(), QgsCoordinateTransform(), readXML(), setDestCRS(), setDestCRSID(), setSourceCrs(), and QgsCoordinateTransformCache::transform().

void QgsCoordinateTransform::invalidTransformInput ( ) const

signal

Signal when an invalid pj_transform() has occured.

Referenced by transformCoords().

bool QgsCoordinateTransform::isInitialised ( ) const

inline

Flag to indicate whether the coordinate systems have been initialised

Returns: true if initialised, otherwise false

Definition at line 198 of file qgscoordinatetransform.h.

Referenced by operator<<().

bool QgsCoordinateTransform::isShortCircuited ( )

inline

See if the transform short circuits because src and dest are equivalent

Returns: bool True if it short circuits

Definition at line 203 of file qgscoordinatetransform.h.

Referenced by operator<<().

bool QgsCoordinateTransform::readXML ( QDomNode & theNode )

slot

Restores state from the given Dom node.

Parameters

theNode The node from which state will be restored

Returns: bool True on success, False on failure

Definition at line 704 of file qgscoordinatetransform.cpp.

References initialise(), mDestCRS, mDestinationDatumTransform, mSourceCRS, mSourceDatumTransform, QgsDebugMsg, and QgsCoordinateReferenceSystem::readXML().

void QgsCoordinateTransform::searchDatumTransform	(	const QString &	sql,
		QList< int > &	transforms
	)

staticprivate

Definition at line 859 of file qgscoordinatetransform.cpp.

References QgsApplication::srsDbFilePath().

Referenced by datumTransformations().

void QgsCoordinateTransform::setDestCRS ( const QgsCoordinateReferenceSystem & theCRS )

Mutator for dest QgsCoordinateReferenceSystem

Parameters

theCRS of the destination coordinate system

Definition at line 144 of file qgscoordinatetransform.cpp.

References initialise(), and mDestCRS.

Referenced by QgsAtlasComposition::computeExtent(), and QgsDistanceArea::setEllipsoid().

void QgsCoordinateTransform::setDestCRSID ( long theCRSID )

Change the destination coordinate system by passing it a qgis srsid A QGIS srsid is a unique key value to an entry on the tbl_srs in the srs.db sqlite database.

Note: This slot will usually be called if the project properties change and a different coordinate system is selected.; This coord transform will be reinitialised when this slot is called to check if short circuiting is needed or not etc.

Parameters

theCRSID - A long representing the srsid of the srs to be used

todo Add some logic here to determine if the srsid is a system or user one

Definition at line 150 of file qgscoordinatetransform.cpp.

References QgsCoordinateReferenceSystem::createFromSrsId(), initialise(), and mDestCRS.

void QgsCoordinateTransform::setDestinationDatumTransform ( int dt )

inline

Definition at line 228 of file qgscoordinatetransform.h.

Referenced by clone(), and QgsCoordinateTransformCache::transform().

void QgsCoordinateTransform::setFinder ( )

private

Finder for PROJ grid files.

Definition at line 755 of file qgscoordinatetransform.cpp.

References finder().

Referenced by QgsCoordinateTransform().

void QgsCoordinateTransform::setSourceCrs ( const QgsCoordinateReferenceSystem & theCRS )

Set the source (layer) QgsCoordinateReferenceSystem

Parameters

theCRS QgsCoordinateReferenceSystem representation of the layer's coordinate system

Definition at line 139 of file qgscoordinatetransform.cpp.

References initialise(), and mSourceCRS.

Referenced by QgsAtlasComposition::computeExtent(), QgsDistanceArea::setSourceAuthId(), and QgsDistanceArea::setSourceCrs().

void QgsCoordinateTransform::setSourceDatumTransform ( int dt )

inline

Definition at line 226 of file qgscoordinatetransform.h.

Referenced by clone(), and QgsCoordinateTransformCache::transform().

const QgsCoordinateReferenceSystem& QgsCoordinateTransform::sourceCrs ( ) const

inline

Get the QgsCoordinateReferenceSystem representation of the layer's coordinate system

Returns: QgsCoordinateReferenceSystem of the layer's coordinate system

Definition at line 116 of file qgscoordinatetransform.h.

Referenced by QgsDistanceArea::_copy(), clone(), QgsDistanceArea::convertMeasurement(), QgsVectorLayer::draw(), QgsDistanceArea::measureLine(), operator<<(), and QgsMapRenderer::outputExtentToLayerExtent().

int QgsCoordinateTransform::sourceDatumTransform ( ) const

inline

Definition at line 225 of file qgscoordinatetransform.h.

Referenced by clone(), and QgsRasterLayer::draw().

QString QgsCoordinateTransform::stripDatumTransform ( const QString & proj4 )

staticprivate

Removes +nadgrids and +towgs84 from proj4 string.

Definition at line 839 of file qgscoordinatetransform.cpp.

Referenced by initialise().

QgsPoint QgsCoordinateTransform::transform	(	const QgsPoint	p,
		TransformDirection	direction = `ForwardTransform`
	)		const

Transform the point from Source Coordinate System to Destination Coordinate System If the direction is ForwardTransform then coordinates are transformed from layer CS –> map canvas CS, otherwise points are transformed from map canvas CS to layerCS.

Parameters

p	Point to transform
direction	TransformDirection (defaults to ForwardTransform)

Returns: QgsPoint in Destination Coordinate System

Definition at line 276 of file qgscoordinatetransform.cpp.

References mInitialisedFlag, mShortCircuit, QgsDebugMsg, transformCoords(), QgsPoint::x(), and QgsPoint::y().

Referenced by QgsDistanceArea::bearing(), QgsRasterProjector::calcCP(), QgsRasterProjector::checkCols(), QgsRasterProjector::checkRows(), QgsVectorLayer::draw(), QgsMapRenderer::layerToMapCoordinates(), QgsMapRenderer::mapToLayerCoordinates(), QgsDistanceArea::measureLine(), QgsDistanceArea::measurePolygon(), QgsLabel::renderLabel(), QgsRasterLayerSaveAsDialog::setResolution(), QgsMapRenderer::splitLayersExtent(), transform(), and transformBoundingBox().

QgsPoint QgsCoordinateTransform::transform	(	const double	x,
		const double	y = `0`,
		TransformDirection	direction = `ForwardTransform`
	)		const

Transform the point specified by x,y from Source Coordinate System to Destination Coordinate System If the direction is ForwardTransform then coordinates are transformed from layer CS –> map canvas CS, otherwise points are transformed from map canvas CS to layerCS.

Parameters

x	x cordinate of point to transform
y	y coordinate of point to transform
direction	TransformDirection (defaults to ForwardTransform)

Returns: QgsPoint in Destination Coordinate System

Definition at line 299 of file qgscoordinatetransform.cpp.

References QgsDebugMsg, and transform().

QgsRectangle QgsCoordinateTransform::transform	(	const QgsRectangle	theRect,
		TransformDirection	direction = `ForwardTransform`
	)		const

Transform a QgsRectangle to the dest Coordinate system If the direction is ForwardTransform then coordinates are transformed from layer CS –> map canvas CS, otherwise points are transformed from map canvas CS to layerCS.

Parameters

theRect	rect to transform
direction	TransformDirection (defaults to ForwardTransform)

Returns: QgsRectangle in Destination Coordinate System

Definition at line 313 of file qgscoordinatetransform.cpp.

References mInitialisedFlag, mShortCircuit, QgsDebugMsg, transformCoords(), QgsRectangle::xMaximum(), QgsRectangle::xMinimum(), QgsRectangle::yMaximum(), and QgsRectangle::yMinimum().

QgsRectangle QgsCoordinateTransform::transformBoundingBox	(	const QgsRectangle	theRect,
		TransformDirection	direction = `ForwardTransform`
	)		const

Transform a QgsRectangle to the dest Coordinate system If the direction is ForwardTransform then coordinates are transformed from layer CS –> map canvas CS, otherwise points are transformed from map canvas CS to layerCS. It assumes that rect is a bounding box, and creates a bounding box in the proejcted CS, so that all points in source rectangle is within returned rectangle.

Parameters

theRect	rect to transform
direction	TransformDirection (defaults to ForwardTransform)

Returns: QgsRectangle in Destination Coordinate System

Definition at line 512 of file qgscoordinatetransform.cpp.

References QgsRectangle::combineExtentWith(), QgsRectangle::height(), QgsRectangle::isEmpty(), mInitialisedFlag, mShortCircuit, QgsDebugMsg, QgsRectangle::setMinimal(), QgsRectangle::toString(), transform(), transformCoords(), QgsRectangle::width(), QgsRectangle::xMinimum(), and QgsRectangle::yMinimum().

Referenced by QgsRasterLayer::draw(), QgsMapRenderer::layerExtentToOutputExtent(), QgsMapRenderer::outputExtentToLayerExtent(), QgsMapRenderer::setDestinationCrs(), QgsRasterLayerSaveAsDialog::setOutputExtent(), and QgsMapRenderer::splitLayersExtent().

void QgsCoordinateTransform::transformCoords	(	const int &	numPoint,
		double *	x,
		double *	y,
		double *	z,
		TransformDirection	direction = `ForwardTransform`
	)		const

Transform an array of coordinates to a different Coordinate System If the direction is ForwardTransform then coordinates are transformed from layer CS –> map canvas CS, otherwise points are transformed from map canvas CS to layerCS.

Parameters

numPoint	number of coordinates in arrays
x	array of x coordinates to transform
y	array of y coordinates to transform
z	array of z coordinates to transform
direction	TransformDirection (defaults to ForwardTransform)

Returns: QgsRectangle in Destination Coordinate System

Definition at line 598 of file qgscoordinatetransform.cpp.

References ForwardTransform, invalidTransformInput(), QgsCoordinateReferenceSystem::isValid(), QgsMessageLog::logMessage(), mDestCRS, mDestinationProjection, mSourceCRS, mSourceProjection, QgsDebugMsg, ReverseTransform, QgsCoordinateReferenceSystem::toProj4(), and tr.

Referenced by transform(), transformBoundingBox(), transformInPlace(), and transformPolygon().

void QgsCoordinateTransform::transformInPlace	(	double &	x,
		double &	y,
		double &	z,
		TransformDirection	direction = `ForwardTransform`
	)		const

Definition at line 349 of file qgscoordinatetransform.cpp.

References mInitialisedFlag, mShortCircuit, QgsDebugMsg, and transformCoords().

Referenced by QgsFeatureRendererV2::_getPoint(), QgsRasterProjector::preciseSrcRowCol(), QgsPalLabeling::registerDiagramFeature(), QgsPalLayerSettings::registerFeature(), and QgsGeometry::transformVertex().

void QgsCoordinateTransform::transformInPlace	(	QVector< double > &	x,
		QVector< double > &	y,
		QVector< double > &	z,
		TransformDirection	direction = `ForwardTransform`
	)		const