QgsCoordinateTransform Class Reference
[QGIS core library]

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

#include <qgscoordinatetransform.h>

Collaboration diagram for QgsCoordinateTransform:

List of all members.

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

void setSourceCrs (const QgsCoordinateReferenceSystem &theCRS)

void setDestCRS (const QgsCoordinateReferenceSystem &theCRS)

QgsCoordinateReferenceSystem & sourceCrs ()

QgsCoordinateReferenceSystem & destCRS ()

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 (std::vector< double > &x, std::vector< double > &y, std::vector< double > &z, 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)

Private Member Functions

void setFinder ()

Private Attributes

bool mShortCircuit

bool mInitialisedFlag

QgsCoordinateReferenceSystem mSourceCRS

QgsCoordinateReferenceSystem mDestCRS

projPJ mSourceProjection

projPJ mDestinationProjection

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 92 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 36 of file qgscoordinatetransform.cpp.

References setFinder().

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 41 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 51 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 58 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 71 of file qgscoordinatetransform.cpp.

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

QgsCoordinateTransform::~QgsCoordinateTransform ( )

destructor

Definition at line 86 of file qgscoordinatetransform.cpp.

References mDestinationProjection, and mSourceProjection.

Member Function Documentation

void QgsCoordinateTransform::setSourceCrs ( const QgsCoordinateReferenceSystem & theCRS )

Set the source (layer) QgsCoordinateReferenceSystem

Parameters:

theCRS

QgsCoordinateReferenceSystem representation of the layer's coordinate system

Definition at line 99 of file qgscoordinatetransform.cpp.

References initialise(), and mSourceCRS.

Referenced by QgsDistanceArea::setSourceCrs(), and QgsDistanceArea::setSourceEpsgCrsId().

void QgsCoordinateTransform::setDestCRS ( const QgsCoordinateReferenceSystem & theCRS )

Mutator for dest QgsCoordinateReferenceSystem

Parameters:

theCRS

of the destination coordinate system

Definition at line 104 of file qgscoordinatetransform.cpp.

References initialise(), and mDestCRS.

Referenced by QgsDistanceArea::setEllipsoid().

QgsCoordinateReferenceSystem& QgsCoordinateTransform::sourceCrs ( ) [inline]

Get the QgsCoordinateReferenceSystem representation of the layer's coordinate system

Returns:: QgsCoordinateReferenceSystem of the layer's coordinate system

Definition at line 114 of file qgscoordinatetransform.h.

Referenced by operator<<(), and QgsLabel::renderLabel().

QgsCoordinateReferenceSystem& QgsCoordinateTransform::destCRS ( ) [inline]

Get the QgsCoordinateReferenceSystem representation of the map canvas coordinate system

Returns:: QgsCoordinateReferenceSystem of the map canvas coordinate system

Definition at line 120 of file qgscoordinatetransform.h.

Referenced by operator<<(), and QgsLabel::renderLabel().

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 213 of file qgscoordinatetransform.cpp.

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

Referenced by QgsDistanceArea::bearing(), QgsDistanceArea::measureLine(), QgsDistanceArea::measurePolygon(), QgsLabel::renderLabel(), and transform().

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 235 of file qgscoordinatetransform.cpp.

References QgsDebugMsg, and transform().

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 336 of file qgscoordinatetransform.cpp.

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

Referenced by QgsPALObjectPositionManager::findObjectPositions().

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

Definition at line 288 of file qgscoordinatetransform.cpp.

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

Referenced by QgsFeatureRendererV2::_getLineString(), QgsFeatureRendererV2::_getPoint(), QgsFeatureRendererV2::_getPolygon(), QgsVectorLayer::transformPoint(), QgsVectorLayer::transformPoints(), and QgsGeometry::transformVertex().

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

Definition at line 309 of file qgscoordinatetransform.cpp.

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

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 249 of file qgscoordinatetransform.cpp.

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

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 410 of file qgscoordinatetransform.cpp.

References QgsLogger::critical(), ForwardTransform, invalidTransformInput(), QgsCoordinateReferenceSystem::isValid(), mDestCRS, mDestinationProjection, mSourceCRS, mSourceProjection, QgsDebugMsg, ReverseTransform, and QgsCoordinateReferenceSystem::toProj4().

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

bool QgsCoordinateTransform::isInitialised ( ) const [inline]

Flag to indicate whether the coordinate systems have been initialised

Returns:: true if initialised, otherwise false

Definition at line 186 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 191 of file qgscoordinatetransform.h.

Referenced by operator<<().

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 111 of file qgscoordinatetransform.cpp.

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

void QgsCoordinateTransform::initialise ( ) [slot]

initialise is used to actually create the Transformer instance

Definition at line 120 of file qgscoordinatetransform.cpp.

References QgsCoordinateReferenceSystem::createFromProj4(), QgsCoordinateReferenceSystem::isValid(), mDestCRS, mDestinationProjection, mInitialisedFlag, mShortCircuit, mSourceCRS, mSourceProjection, QgsDebugMsg, QgsDebugMsgLevel, and QgsCoordinateReferenceSystem::toProj4().

Referenced by QgsCoordinateTransform(), readXML(), setDestCRS(), setDestCRSID(), and setSourceCrs().

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 514 of file qgscoordinatetransform.cpp.

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

bool QgsCoordinateTransform::writeXML	(	QDomNode &	theNode,
		QDomDocument &	theDoc
	)			`[slot]`

Stores state to the given Dom node in the given document

Parameters:

	theNode	The node in which state will be restored
	theDoc	The document in which state will be stored

Returns:: bool True on success, False on failure

Definition at line 530 of file qgscoordinatetransform.cpp.

References mDestCRS, mSourceCRS, and QgsCoordinateReferenceSystem::writeXML().

void QgsCoordinateTransform::invalidTransformInput ( ) const [signal]

Signal when an invalid pj_transform() has occured.

Referenced by transformCoords().

void QgsCoordinateTransform::setFinder ( ) [private]

Finder for PROJ grid files.

Definition at line 558 of file qgscoordinatetransform.cpp.

References finder().

Referenced by QgsCoordinateTransform().

Member Data Documentation

bool QgsCoordinateTransform::mShortCircuit [private]

Flag to indicate that the source and destination coordinate systems are equal and not transformation needs to be done

Definition at line 231 of file qgscoordinatetransform.h.

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

bool QgsCoordinateTransform::mInitialisedFlag [private]

flag to show whether the transform is properly initialised or not

Definition at line 236 of file qgscoordinatetransform.h.

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

QgsCoordinateReferenceSystem QgsCoordinateTransform::mSourceCRS [private]

QgsCoordinateReferenceSystem of the source (layer) coordinate system

Definition at line 241 of file qgscoordinatetransform.h.

Referenced by initialise(), QgsCoordinateTransform(), readXML(), setSourceCrs(), transformCoords(), and writeXML().

QgsCoordinateReferenceSystem QgsCoordinateTransform::mDestCRS [private]

QgsCoordinateReferenceSystem of the destination (map canvas) coordinate system

Definition at line 246 of file qgscoordinatetransform.h.

Referenced by initialise(), QgsCoordinateTransform(), readXML(), setDestCRS(), setDestCRSID(), transformCoords(), and writeXML().

projPJ QgsCoordinateTransform::mSourceProjection [private]

Proj4 data structure of the source projection (layer coordinate system)

Definition at line 251 of file qgscoordinatetransform.h.

Referenced by initialise(), transformCoords(), and ~QgsCoordinateTransform().

projPJ QgsCoordinateTransform::mDestinationProjection [private]

Proj4 data structure of the destination projection (map canvas coordinate system)

Definition at line 256 of file qgscoordinatetransform.h.

Referenced by initialise(), transformCoords(), and ~QgsCoordinateTransform().

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

src/core/qgscoordinatetransform.h
src/core/qgscoordinatetransform.cpp


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
void	setSourceCrs (const QgsCoordinateReferenceSystem &theCRS)
void	setDestCRS (const QgsCoordinateReferenceSystem &theCRS)
QgsCoordinateReferenceSystem &	sourceCrs ()
QgsCoordinateReferenceSystem &	destCRS ()
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 (std::vector< double > &x, std::vector< double > &y, std::vector< double > &z, 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)
Private Member Functions
void	setFinder ()
Private Attributes
bool	mShortCircuit
bool	mInitialisedFlag
QgsCoordinateReferenceSystem	mSourceCRS
QgsCoordinateReferenceSystem	mDestCRS
projPJ	mSourceProjection
projPJ	mDestinationProjection

QgsCoordinateTransform Class Reference [QGIS core library]

Public Types

Public Slots

Signals

Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation

QgsCoordinateTransform Class Reference
[QGIS core library]