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/***************************************************************************
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QgsCoordinateTransform.h - Coordinate Transforms
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copyright : (C) 2004 Tim Sutton
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email : tim at linfiniti.com
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***************************************************************************/
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/***************************************************************************
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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***************************************************************************/
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#ifndef QGSCOORDINATETRANSFORM_H
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#define QGSCOORDINATETRANSFORM_H
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#include "qgsrectangle.h"
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#include "qgscsexception.h"
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#include "qgscoordinatereferencesystem.h"
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* Class for doing transforms between two map coordinate systems.
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* This class can convert map coordinates to a different coordinate reference system.
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* It is normally associated with a map layer and is used to transform between the
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* layer's coordinate system and the coordinate system of the map canvas, although
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* it can be used in a more general sense to transform coordinates.
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* All references to source and destination coordinate systems refer to
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* layer and map canvas respectively. All operations are from the perspective
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* of the layer. For example, a forward transformation transforms coordinates from the
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* layers coordinate system to the map canvas.
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class CORE_EXPORT QgsCoordinateTransform: public QObject
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/*! Default constructor. Make sure you use initialised() manually if you use this one! */
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QgsCoordinateTransform() ;
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/** Constructs a QgsCoordinateTransform using QgsCoordinateReferenceSystem objects.
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* @param theSource CRS, typically of the layer's coordinate system
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* @param theDest CRS, typically of the map canvas coordinate system
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QgsCoordinateTransform( const QgsCoordinateReferenceSystem& theSource,
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const QgsCoordinateReferenceSystem& theDest );
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/** Constructs a QgsCoordinateTransform using CRS ID of source and destination CRS */
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QgsCoordinateTransform( long theSourceSrsId, long theDestSrsId );
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* Constructs a QgsCoordinateTransform using the Well Known Text representation
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* of the layer and map canvas coordinate systems
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* @param theSourceWkt Wkt, typically of the layer's coordinate system
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* @param theDestWkt Wkt, typically of the map canvas coordinate system
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QgsCoordinateTransform( QString theSourceWkt, QString theDestWkt );
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* Constructs a QgsCoordinateTransform using a Spatial Reference Id
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* of the layer and map canvas coordinate system as Wkt
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* @param theSourceSrid Spatial Ref Id of the layer's coordinate system
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* @param theSourceWkt Wkt of the map canvas coordinate system
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* @param theSourceCRSType On of the enum members defined in QgsCoordinateReferenceSystem::CrsType
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QgsCoordinateTransform( long theSourceSrid,
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QgsCoordinateReferenceSystem::CrsType theSourceCRSType = QgsCoordinateReferenceSystem::PostgisCrsId );
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~QgsCoordinateTransform();
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//! Enum used to indicate the direction (forward or inverse) of the transform
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enum TransformDirection
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ForwardTransform, /*!< Transform from source to destination CRS. */
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ReverseTransform /*!< Transform from destination to source CRS. */
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* Set the source (layer) QgsCoordinateReferenceSystem
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* @param theCRS QgsCoordinateReferenceSystem representation of the layer's coordinate system
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void setSourceCrs( const QgsCoordinateReferenceSystem& theCRS );
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* Mutator for dest QgsCoordinateReferenceSystem
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* @param theCRS of the destination coordinate system
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void setDestCRS( const QgsCoordinateReferenceSystem& theCRS );
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* Get the QgsCoordinateReferenceSystem representation of the layer's coordinate system
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* @return QgsCoordinateReferenceSystem of the layer's coordinate system
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QgsCoordinateReferenceSystem& sourceCrs() { return mSourceCRS; }
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* Get the QgsCoordinateReferenceSystem representation of the map canvas coordinate system
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* @return QgsCoordinateReferenceSystem of the map canvas coordinate system
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QgsCoordinateReferenceSystem& destCRS() { return mDestCRS; }
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/*! Transform the point from Source Coordinate System to Destination Coordinate System
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* If the direction is ForwardTransform then coordinates are transformed from layer CS --> map canvas CS,
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* otherwise points are transformed from map canvas CS to layerCS.
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* @param p Point to transform
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* @param direction TransformDirection (defaults to ForwardTransform)
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* @return QgsPoint in Destination Coordinate System
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QgsPoint transform( const QgsPoint p, TransformDirection direction = ForwardTransform ) const;
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/*! Transform the point specified by x,y from Source Coordinate System to Destination Coordinate System
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* If the direction is ForwardTransform then coordinates are transformed from layer CS --> map canvas CS,
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* otherwise points are transformed from map canvas CS to layerCS.
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* @param x x cordinate of point to transform
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* @param y y coordinate of point to transform
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* @param direction TransformDirection (defaults to ForwardTransform)
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* @return QgsPoint in Destination Coordinate System
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QgsPoint transform( const double x, const double y, TransformDirection direction = ForwardTransform ) const;
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/*! Transform a QgsRectangle to the dest Coordinate system
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* If the direction is ForwardTransform then coordinates are transformed from layer CS --> map canvas CS,
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* otherwise points are transformed from map canvas CS to layerCS.
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* It assumes that rect is a bounding box, and creates a bounding box
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* in the proejcted CS, so that all points in source rectangle is within
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* returned rectangle.
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* @param QgsRectangle rect to transform
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* @param direction TransformDirection (defaults to ForwardTransform)
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* @return QgsRectangle in Destination Coordinate System
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QgsRectangle transformBoundingBox( const QgsRectangle theRect, TransformDirection direction = ForwardTransform ) const;
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// Same as for the other transform() functions, but alters the x
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// and y variables in place. The second one works with good old-fashioned
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void transformInPlace( double& x, double& y, double &z, TransformDirection direction = ForwardTransform ) const;
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void transformInPlace( std::vector<double>& x, std::vector<double>& y, std::vector<double>& z,
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TransformDirection direction = ForwardTransform ) const;
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/*! Transform a QgsRectangle to the dest Coordinate system
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* If the direction is ForwardTransform then coordinates are transformed from layer CS --> map canvas CS,
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* otherwise points are transformed from map canvas CS to layerCS.
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* @param QgsRectangle rect to transform
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* @param direction TransformDirection (defaults to ForwardTransform)
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* @return QgsRectangle in Destination Coordinate System
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QgsRectangle transform( const QgsRectangle theRect, TransformDirection direction = ForwardTransform ) const;
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/*! Transform an array of coordinates to a different Coordinate System
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* If the direction is ForwardTransform then coordinates are transformed from layer CS --> map canvas CS,
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* otherwise points are transformed from map canvas CS to layerCS.
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* @param x x cordinate of point to transform
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* @param y y coordinate of point to transform
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* @param direction TransformDirection (defaults to ForwardTransform)
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* @return QgsRectangle in Destination Coordinate System
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void transformCoords( const int &numPoint, double *x, double *y, double *z, TransformDirection direction = ForwardTransform ) const;
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* Flag to indicate whether the coordinate systems have been initialised
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* @return true if initialised, otherwise false
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bool isInitialised() const {return mInitialisedFlag;};
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/*! See if the transform short circuits because src and dest are equivalent
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* @return bool True if it short circuits
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bool isShortCircuited() {return mShortCircuit;};
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/*! Change the destination coordinate system by passing it a qgis srsid
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* A QGIS srsid is a unique key value to an entry on the tbl_srs in the
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* srs.db sqlite database.
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* @note This slot will usually be called if the
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* project properties change and a different coordinate system is
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* @note This coord transform will be reinitialised when this slot is called
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* to check if short circuiting is needed or not etc.
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* @param theCRSID - A long representing the srsid of the srs to be used */
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void setDestCRSID( long theCRSID );
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//!initialise is used to actually create the Transformer instance
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/*! Restores state from the given Dom node.
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* @param theNode The node from which state will be restored
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* @return bool True on success, False on failure
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bool readXML( QDomNode & theNode );
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/*! Stores state to the given Dom node in the given document
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* @param theNode The node in which state will be restored
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* @param theDom The document in which state will be stored
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* @return bool True on success, False on failure
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bool writeXML( QDomNode & theNode, QDomDocument & theDoc );
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/** Signal when an invalid pj_transform() has occured */
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void invalidTransformInput() const;
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* Flag to indicate that the source and destination coordinate systems are
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* equal and not transformation needs to be done
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* flag to show whether the transform is properly initialised or not
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bool mInitialisedFlag;
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* QgsCoordinateReferenceSystem of the source (layer) coordinate system
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QgsCoordinateReferenceSystem mSourceCRS;
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* QgsCoordinateReferenceSystem of the destination (map canvas) coordinate system
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QgsCoordinateReferenceSystem mDestCRS;
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* Proj4 data structure of the source projection (layer coordinate system)
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projPJ mSourceProjection;
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* Proj4 data structure of the destination projection (map canvas coordinate system)
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projPJ mDestinationProjection;
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* Finder for PROJ grid files.
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//! Output stream operator
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inline std::ostream& operator << ( std::ostream& os, const QgsCoordinateTransform &r )
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QString mySummary( "\n%%%%%%%%%%%%%%%%%%%%%%%%\nCoordinate Transform def begins:" );
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mySummary += "\n\tInitialised? : ";
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if ( r.isInitialised() )
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//do nothing this is a dummy
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if (r.isInitialised())
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mySummary += "\n\tShort Circuit? : " ;
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if (r.isShortCircuited())
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mySummary += "\n\tSource Spatial Ref Sys : ";
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mySummary << r.sourceCrs();
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mySummary += "Undefined" ;
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mySummary += "\n\tDest Spatial Ref Sys : " ;
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mySummary << r.destCRS();
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mySummary += "Undefined" ;
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mySummary += ( "\nCoordinate Transform def ends \n%%%%%%%%%%%%%%%%%%%%%%%%\n" );
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return os << mySummary.toLocal8Bit().data() << std::endl;
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#endif // QGSCOORDINATETRANSFORM_H
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src/core/qgscoordinatetransform.h
