QGIS API Documentation 3.40.0-Bratislava (b56115d8743)
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This class represents a coordinate reference system (CRS). More...
#include <qgscoordinatereferencesystem.h>
Public Types | |
enum | CrsType { InternalCrsId , PostgisCrsId , EpsgCrsId } |
Enumeration of types of IDs accepted in createFromId() method. More... | |
Public Member Functions | |
QgsCoordinateReferenceSystem () | |
Constructs an invalid CRS object. | |
QgsCoordinateReferenceSystem (const QgsCoordinateReferenceSystem &srs) | |
QgsCoordinateReferenceSystem (const QString &definition) | |
Constructs a CRS object from a string definition using createFromString() | |
Q_DECL_DEPRECATED | QgsCoordinateReferenceSystem (long id, CrsType type=PostgisCrsId) |
Constructor. | |
~QgsCoordinateReferenceSystem () | |
QString | authid () const |
Returns the authority identifier for the CRS. | |
QList< Qgis::CrsAxisDirection > | axisOrdering () const |
Returns an ordered list of the axis directions reflecting the native axis order for the CRS. | |
QgsRectangle | bounds () const |
Returns the approximate bounds for the region the CRS is usable within. | |
QString | celestialBodyName () const |
Attempts to retrieve the name of the celestial body associated with the CRS (e.g. | |
double | coordinateEpoch () const |
Returns the coordinate epoch, as a decimal year. | |
Q_DECL_DEPRECATED bool | createFromId (long id, CrsType type=PostgisCrsId) |
Sets this CRS by lookup of the given ID in the CRS database. | |
bool | createFromOgcWmsCrs (const QString &crs) |
Sets this CRS to the given OGC WMS-format Coordinate Reference Systems. | |
bool | createFromProj (const QString &projString, bool identify=true) |
Sets this CRS by passing it a PROJ style formatted string. | |
Q_DECL_DEPRECATED bool | createFromProj4 (const QString &projString) |
Sets this CRS by passing it a PROJ style formatted string. | |
bool | createFromProjObject (PJ *object) |
Sets this CRS by passing it a PROJ PJ object, corresponding to a PROJ CRS object. | |
Q_DECL_DEPRECATED bool | createFromSrid (long srid) |
Sets this CRS by lookup of the given PostGIS SRID in the CRS database. | |
bool | createFromSrsId (long srsId) |
Sets this CRS by lookup of internal QGIS CRS ID in the CRS database. | |
bool | createFromString (const QString &definition) |
Set up this CRS from a string definition. | |
bool | createFromUserInput (const QString &definition) |
Set up this CRS from various text formats. | |
bool | createFromWkt (const QString &wkt) |
Sets this CRS using a WKT definition. | |
QgsDatumEnsemble | datumEnsemble () const |
Attempts to retrieve datum ensemble details from the CRS. | |
QString | description () const |
Returns the descriptive name of the CRS, e.g., "WGS 84" or "GDA 94 / Vicgrid94". | |
QString | ellipsoidAcronym () const |
Returns the ellipsoid acronym for the ellipsoid used by the CRS. | |
QgsProjectionFactors | factors (const QgsPoint &point) const |
Calculate various cartographic properties, such as scale factors, angular distortion and meridian convergence for the CRS at the given geodetic point (in geographic coordinates). | |
Q_DECL_DEPRECATED long | findMatchingProj () |
Walks the CRS databases (both system and user database) trying to match stored PROJ string to a database entry in order to fill in further pieces of information about CRS. | |
QString | geographicCrsAuthId () const |
Returns auth id of related geographic CRS. | |
bool | hasAxisInverted () const |
Returns whether the axis order is inverted for the CRS compared to the order east/north (longitude/latitude). | |
bool | hasVerticalAxis () const |
Returns true if the CRS has a vertical axis. | |
QgsCoordinateReferenceSystem | horizontalCrs () const |
Returns the horizontal CRS associated with this CRS object. | |
bool | isDeprecated () const |
Returns true if the CRS is considered deprecated. | |
bool | isDynamic () const |
Returns true if the CRS is a dynamic CRS. | |
bool | isGeographic () const |
Returns whether the CRS is a geographic CRS (using lat/lon coordinates) | |
bool | isValid () const |
Returns whether this CRS is correctly initialized and usable. | |
Qgis::DistanceUnit | mapUnits () const |
Returns the units for the projection used by the CRS. | |
Qgis::CrsDefinitionFormat | nativeFormat () const |
Returns the native format for the CRS definition. | |
QgsProjOperation | operation () const |
Returns information about the PROJ operation associated with the coordinate reference system, for example the projection method used by the CRS. | |
operator QVariant () const | |
Allows direct construction of QVariants from QgsCoordinateReferenceSystem. | |
bool | operator!= (const QgsCoordinateReferenceSystem &srs) const |
QgsCoordinateReferenceSystem & | operator= (const QgsCoordinateReferenceSystem &srs) |
bool | operator== (const QgsCoordinateReferenceSystem &srs) const |
long | postgisSrid () const |
Returns PostGIS SRID for the CRS. | |
QString | projectionAcronym () const |
Returns the projection acronym for the projection used by the CRS. | |
PJ * | projObject () const |
Returns the underlying PROJ PJ object corresponding to the CRS, or nullptr if the CRS is invalid. | |
bool | readXml (const QDomNode &node) |
Restores state from the given DOM node. | |
long | saveAsUserCrs (const QString &name, Qgis::CrsDefinitionFormat nativeFormat=Qgis::CrsDefinitionFormat::Wkt) |
Saves the CRS as a new custom ("USER") CRS. | |
void | setCoordinateEpoch (double epoch) |
Sets the coordinate epoch, as a decimal year. | |
void | setNativeFormat (Qgis::CrsDefinitionFormat format) |
Sets the native format for the CRS definition. | |
void | setValidationHint (const QString &html) |
Set user hint for validation. | |
long | srsid () const |
Returns the internal CRS ID, if available. | |
QgsCoordinateReferenceSystem | toGeographicCrs () const |
Returns the geographic CRS associated with this CRS object. | |
QString | toOgcUri () const |
Returns the crs as OGC URI (format: http://www.opengis.net/def/crs/OGC/1.3/CRS84) Returns an empty string on failure. | |
QString | toOgcUrn () const |
Returns the crs as OGC URN (format: urn:ogc:def:crs:OGC:1.3:CRS84) Returns an empty string on failure. | |
QString | toProj () const |
Returns a Proj string representation of this CRS. | |
Q_DECL_DEPRECATED QString | toProj4 () const |
Returns a Proj string representation of this CRS. | |
QString | toWkt (Qgis::CrsWktVariant variant=Qgis::CrsWktVariant::Wkt1Gdal, bool multiline=false, int indentationWidth=4) const |
Returns a WKT representation of this CRS. | |
Qgis::CrsType | type () const |
Returns the type of the CRS. | |
void | updateDefinition () |
Updates the definition and parameters of the coordinate reference system to their latest values. | |
QString | userFriendlyIdentifier (Qgis::CrsIdentifierType type=Qgis::CrsIdentifierType::MediumString) const |
Returns a user friendly identifier for the CRS. | |
void | validate () |
Perform some validation on this CRS. | |
QString | validationHint () const |
Gets user hint for validation. | |
QgsCoordinateReferenceSystem | verticalCrs () const |
Returns the vertical CRS associated with this CRS object. | |
bool | writeXml (QDomNode &node, QDomDocument &doc) const |
Stores state to the given Dom node in the given document. | |
Static Public Member Functions | |
static Q_DECL_DEPRECATED void | clearRecentCoordinateReferenceSystems () |
Cleans the list of recently used CRS. | |
static QgsCoordinateReferenceSystem | createCompoundCrs (const QgsCoordinateReferenceSystem &horizontalCrs, const QgsCoordinateReferenceSystem &verticalCrs, QString &error) |
Given a horizontal and vertical CRS, attempts to create a compound CRS from them. | |
static CUSTOM_CRS_VALIDATION | customCrsValidation () |
Gets custom function. | |
static Q_INVOKABLE QgsCoordinateReferenceSystem | fromEpsgId (long epsg) |
Creates a CRS from a given EPSG ID. | |
static QgsCoordinateReferenceSystem | fromOgcWmsCrs (const QString &ogcCrs) |
Creates a CRS from a given OGC WMS-format Coordinate Reference System string. | |
static QgsCoordinateReferenceSystem | fromProj (const QString &proj) |
Creates a CRS from a proj style formatted string. | |
static Q_DECL_DEPRECATED QgsCoordinateReferenceSystem | fromProj4 (const QString &proj4) |
Creates a CRS from a proj style formatted string. | |
static QgsCoordinateReferenceSystem | fromProjObject (PJ *object) |
Constructs a QgsCoordinateReferenceSystem from a PROJ PJ object. | |
static QgsCoordinateReferenceSystem | fromSrsId (long srsId) |
Creates a CRS from a specified QGIS SRS ID. | |
static QgsCoordinateReferenceSystem | fromWkt (const QString &wkt) |
Creates a CRS from a WKT spatial ref sys definition string. | |
static void | invalidateCache (bool disableCache=false) |
Clears the internal cache used to initialize QgsCoordinateReferenceSystem objects. | |
static Q_DECL_DEPRECATED void | pushRecentCoordinateReferenceSystem (const QgsCoordinateReferenceSystem &crs) |
Pushes a recently used CRS to the top of the recent CRS list. | |
static Q_DECL_DEPRECATED QList< QgsCoordinateReferenceSystem > | recentCoordinateReferenceSystems () |
Returns a list of recently used CRS. | |
static Q_DECL_DEPRECATED QStringList | recentProjections () |
Returns a list of recently used projections. | |
static Q_DECL_DEPRECATED void | removeRecentCoordinateReferenceSystem (const QgsCoordinateReferenceSystem &crs) |
Removes a CRS from the list of recently used CRS. | |
static void | setCustomCrsValidation (CUSTOM_CRS_VALIDATION f) |
Sets custom function to force valid CRS. | |
static Q_DECL_DEPRECATED void | setupESRIWktFix () |
Make sure that ESRI WKT import is done properly. | |
static int | syncDatabase () |
Update proj.4 parameters in our database from proj.4. | |
static QList< long > | validSrsIds () |
Returns a list of all valid SRS IDs present in the CRS database. | |
Properties | |
QString | authid |
QString | description |
bool | isGeographic |
Qgis::DistanceUnit | mapUnits |
Friends | |
bool CORE_EXPORT | operator< (const QgsCoordinateReferenceSystem &c1, const QgsCoordinateReferenceSystem &c2) |
bool CORE_EXPORT | operator<= (const QgsCoordinateReferenceSystem &c1, const QgsCoordinateReferenceSystem &c2) |
bool CORE_EXPORT | operator> (const QgsCoordinateReferenceSystem &c1, const QgsCoordinateReferenceSystem &c2) |
bool CORE_EXPORT | operator>= (const QgsCoordinateReferenceSystem &c1, const QgsCoordinateReferenceSystem &c2) |
class | QgsCoordinateReferenceSystemRegistry |
class | QgsProjContext |
class | TestQgsCoordinateReferenceSystem |
This class represents a coordinate reference system (CRS).
Coordinate reference system object defines a specific map projection, as well as transformations between different coordinate reference systems. There are various ways how a CRS can be defined: using well-known text (WKT), PROJ string or combination of authority and code (e.g. EPSG:4326). QGIS comes with its internal database of coordinate reference systems (stored in SQLite) that allows lookups of CRS and seamless conversions between the various definitions.
Most commonly one comes across two types of coordinate systems:
Internally QGIS uses proj library for all the math behind coordinate transformations, so in case of any troubles with projections it is best to examine the PROJ representation within the object, as that is the representation that will be ultimately used.
Methods that allow inspection of CRS instances include isValid(), authid(), description(), toWkt(), toProj(), mapUnits() and others. Creation of CRS instances is further described in Object Construction and Copying section below. Transformations between coordinate reference systems are done using QgsCoordinateTransform class.
For example, the following code will create and inspect "British national grid" CRS:
This will produce the following output:
This section gives an overview of various supported CRS definition formats:
Authority and Code: Also referred to as OGC WMS format within QGIS as they have been widely used in OGC standards. These are encoded as <auth>:<code>
, for example EPSG:4326
refers to WGS84 system. EPSG is the most commonly used authority that covers a wide range of coordinate systems around the world.
An extended variant of this format is OGC URN. Syntax of URN for CRS definition is urn:ogc:def:crs:<auth>:[<version>]:<code>
. This class can also parse URNs (versions are currently ignored). For example, WGS84 may be encoded as urn:ogc:def:crs:OGC:1.3:CRS84
.
QGIS adds support for "USER" authority that refers to IDs used internally in QGIS. This variant is best avoided or used with caution as the IDs are not permanent and they refer to different CRS on different machines or user profiles.
PROJ string: This is a string consisting of a series of key/value pairs in the following format: +param1=value1 +param2=value2 [...]
. This is the format natively used by the underlying proj library. For example, the definition of WGS84 looks like this:
Well-known text (WKT): Defined by Open Geospatial Consortium (OGC), this is another common format to define CRS. For WGS84 the OGC WKT definition is the following:
The database of CRS shipped with QGIS is stored in a SQLite database (see QgsApplication::srsDatabaseFilePath()) and it is based on the data files maintained by GDAL project (a variety of .csv and .wkt files).
Sometimes it happens that users need to use a CRS definition that is not well known or that has been only created with a specific purpose (and thus its definition is not available in our database of CRS). Whenever a new CRS definition is seen, it will be added to the local database (in user's home directory, see QgsApplication::qgisUserDatabaseFilePath()). QGIS also features a GUI for management of local custom CRS definitions.
There are therefore two databases: one for shipped CRS definitions and one for custom CRS definitions. Custom CRS have internal IDs (accessible with srsid()) greater or equal to USER_CRS_START_ID. The local CRS databases should never be accessed directly with SQLite functions, instead you should use QgsCoordinateReferenceSystem API for CRS lookups and for managements of custom CRS.
In some cases (most prominently when loading a map layer), QGIS will try to ensure that the given map layer CRS is valid using validate() call. If not, a custom validation function will be called - such function may for example show a GUI for manual CRS selection. The validation function is configured using setCustomCrsValidation(). If validation fails or no validation function is set, the default CRS is assigned (WGS84). QGIS application registers its validation function that will act according to user's settings (either show CRS selector dialog or use project/custom CRS).
The easiest way of creating CRS instances is to use QgsCoordinateReferenceSystem(const QString&) constructor that automatically recognizes definition format from the given string.
Creation of CRS object involves some queries in a local SQLite database, which may be potentially expensive. Consequently, CRS creation methods use an internal cache to avoid unnecessary database lookups. If the CRS database is modified, then it is necessary to call invalidateCache() to ensure that outdated records are not being returned from the cache.
Since QGIS 2.16 QgsCoordinateReferenceSystem objects are implicitly shared.
There are two different flavors of WKT: one is defined by OGC, the other is the standard used by ESRI. They look very similar, but they are not the same. QGIS is able to consume both flavors.
Definition at line 211 of file qgscoordinatereferencesystem.h.
Enumeration of types of IDs accepted in createFromId() method.
Enumerator | |
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InternalCrsId | Internal ID used by QGIS in the local SQLite database. |
PostgisCrsId | SRID used in PostGIS. DEPRECATED – DO NOT USE. |
EpsgCrsId | EPSG code. |
Definition at line 223 of file qgscoordinatereferencesystem.h.
QgsCoordinateReferenceSystem::QgsCoordinateReferenceSystem | ( | ) |
Constructs an invalid CRS object.
Definition at line 105 of file qgscoordinatereferencesystem.cpp.
QgsCoordinateReferenceSystem::~QgsCoordinateReferenceSystem | ( | ) |
Definition at line 268 of file qgscoordinatereferencesystem.cpp.
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explicit |
Constructs a CRS object from a string definition using createFromString()
It supports the following formats:
If no prefix is specified, WKT definition is assumed.
definition | A String containing a coordinate reference system definition. |
Definition at line 112 of file qgscoordinatereferencesystem.cpp.
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explicit |
Constructor.
A CRS object using a PostGIS SRID, an EPSG code or an internal QGIS CRS ID.
id | The ID valid for the chosen CRS ID type |
type | One of the types described in CrsType |
Definition at line 118 of file qgscoordinatereferencesystem.cpp.
QgsCoordinateReferenceSystem::QgsCoordinateReferenceSystem | ( | const QgsCoordinateReferenceSystem & | srs | ) |
Definition at line 126 of file qgscoordinatereferencesystem.cpp.
QString QgsCoordinateReferenceSystem::authid | ( | ) | const |
Returns the authority identifier for the CRS.
The identifier includes both the authority (e.g., EPSG) and the CRS number (e.g., 4326). This is the best method to use when showing a very short CRS identifier to a user, e.g., "EPSG:4326".
If CRS object is a custom CRS (not found in database), the method will return internal QGIS CRS ID with "QGIS" authority, for example "QGIS:100005"
Definition at line 1228 of file qgscoordinatereferencesystem.cpp.
QList< Qgis::CrsAxisDirection > QgsCoordinateReferenceSystem::axisOrdering | ( | ) | const |
Returns an ordered list of the axis directions reflecting the native axis order for the CRS.
Definition at line 834 of file qgscoordinatereferencesystem.cpp.
QgsRectangle QgsCoordinateReferenceSystem::bounds | ( | ) | const |
Returns the approximate bounds for the region the CRS is usable within.
The returned bounds represent the latitude and longitude extent for the projection in the WGS 84 CRS.
Definition at line 1579 of file qgscoordinatereferencesystem.cpp.
QString QgsCoordinateReferenceSystem::celestialBodyName | ( | ) | const |
Attempts to retrieve the name of the celestial body associated with the CRS (e.g.
"Earth").
QgsNotSupportedException | on QGIS builds based on PROJ 8.0 or earlier. |
Definition at line 1427 of file qgscoordinatereferencesystem.cpp.
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static |
Cleans the list of recently used CRS.
Definition at line 3288 of file qgscoordinatereferencesystem.cpp.
double QgsCoordinateReferenceSystem::coordinateEpoch | ( | ) | const |
Returns the coordinate epoch, as a decimal year.
In a dynamic CRS, coordinates of a point on the surface of the Earth may change with time. To be unambiguous the coordinates must always be qualified with the epoch at which they are valid. The coordinate epoch is not necessarily the epoch at which the observation was collected.
Pedantically the coordinate epoch of an observation belongs to the observation, and not to the CRS, however it is often more practical to bind it to the CRS. The coordinate epoch should be specified for dynamic CRS (see isDynamic()).
Definition at line 1454 of file qgscoordinatereferencesystem.cpp.
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Given a horizontal and vertical CRS, attempts to create a compound CRS from them.
Returns an invalid CRS if the inputs are not suitable for a compound CRS, or the compound CRS could not be created for the combination.
horizontalCrs | horizontal component for CRS |
verticalCrs | vertical component for CRS |
error | will be set to a descriptive error if the compound CRS could not be created |
Definition at line 244 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::createFromId | ( | long | id, |
CrsType | type = PostgisCrsId |
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) |
Sets this CRS by lookup of the given ID in the CRS database.
true
on success else false
Definition at line 272 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::createFromOgcWmsCrs | ( | const QString & | crs | ) |
Sets this CRS to the given OGC WMS-format Coordinate Reference Systems.
Accepts both "<auth>:<code>" format and OGC URN "urn:ogc:def:crs:<auth>:[<version>]:<code>". It also recognizes "QGIS", "USER", "CUSTOM" authorities, which all have the same meaning and refer to QGIS internal CRS IDs.
true
on success else false
Definition at line 411 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::createFromProj | ( | const QString & | projString, |
bool | identify = true |
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) |
Sets this CRS by passing it a PROJ style formatted string.
The string will be parsed and the projection and ellipsoid members set and the remainder of the Proj string will be stored in the parameters member. The reason for this is so that we can easily present the user with 'natural language' representation of the projection and ellipsoid by looking them up in the srs.db sqlite database.
We try to match the Proj string to internal QGIS CRS ID using the following logic:
projString | A Proj format string |
identify | if false , no attempts will be made to match the proj string against known CRS authorities. This is much faster, but should only ever be used when it is known in advance that the definition does not correspond to a known or user CRS. This argument is not available in Python. |
true
on success else false
Definition at line 1020 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::createFromProj4 | ( | const QString & | projString | ) |
Sets this CRS by passing it a PROJ style formatted string.
The string will be parsed and the projection and ellipsoid members set and the remainder of the Proj string will be stored in the parameters member. The reason for this is so that we can easily present the user with 'natural language' representation of the projection and ellipsoid by looking them up in the srs.db sqlite database.
We try to match the Proj string to internal QGIS CRS ID using the following logic:
projString | A Proj format string |
true
on success else false
Definition at line 1015 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::createFromProjObject | ( | PJ * | object | ) |
Sets this CRS by passing it a PROJ PJ object, corresponding to a PROJ CRS object.
Ownership of object is not transferred.
Definition at line 3201 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::createFromSrid | ( | long | srid | ) |
Sets this CRS by lookup of the given PostGIS SRID in the CRS database.
srid | The PostGIS SRID for the desired spatial reference system. |
true
on success else false
Definition at line 542 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::createFromSrsId | ( | long | srsId | ) |
Sets this CRS by lookup of internal QGIS CRS ID in the CRS database.
If the srsid is < USER_CRS_START_ID, system CRS database is used, otherwise user's local CRS database from home directory is used.
srsId | The internal QGIS CRS ID for the desired spatial reference system. |
true
on success else false
Definition at line 585 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::createFromString | ( | const QString & | definition | ) |
Set up this CRS from a string definition.
It supports the following formats:
If no prefix is specified, WKT definition is assumed.
definition | A String containing a coordinate reference system definition. |
true
on success else false
Definition at line 295 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::createFromUserInput | ( | const QString & | definition | ) |
Set up this CRS from various text formats.
Valid formats: WKT string, "EPSG:n", "EPSGA:n", "AUTO:proj_id,unit_id,lon0,lat0", "urn:ogc:def:crs:EPSG::n", PROJ string, filename (with WKT, XML or PROJ string), well known name (such as NAD27, NAD83, WGS84 or WGS72), ESRI::[WKT string] (directly or in a file), "IGNF:xxx"
For more details on supported formats see OGRSpatialReference::SetFromUserInput() ( https://gdal.org/doxygen/classOGRSpatialReference.html#aec3c6a49533fe457ddc763d699ff8796 )
definition | A String containing a coordinate reference system definition. |
true
on success else false
Definition at line 373 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::createFromWkt | ( | const QString & | wkt | ) |
Sets this CRS using a WKT definition.
If EPSG code of the WKT definition can be determined, it is extracted and createFromOgcWmsCrs() is used to initialize the object.
wkt | The WKT for the desired spatial reference system. |
true
on success else false
Definition at line 932 of file qgscoordinatereferencesystem.cpp.
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static |
Gets custom function.
Definition at line 2364 of file qgscoordinatereferencesystem.cpp.
QgsDatumEnsemble QgsCoordinateReferenceSystem::datumEnsemble | ( | ) | const |
Attempts to retrieve datum ensemble details from the CRS.
If the CRS does not use a datum ensemble then an invalid QgsDatumEnsemble will be returned.
QgsNotSupportedException | on QGIS builds based on PROJ 7 or earlier. |
Definition at line 1459 of file qgscoordinatereferencesystem.cpp.
QString QgsCoordinateReferenceSystem::description | ( | ) | const |
Returns the descriptive name of the CRS, e.g., "WGS 84" or "GDA 94 / Vicgrid94".
Definition at line 1233 of file qgscoordinatereferencesystem.cpp.
QString QgsCoordinateReferenceSystem::ellipsoidAcronym | ( | ) | const |
Returns the ellipsoid acronym for the ellipsoid used by the CRS.
Definition at line 1284 of file qgscoordinatereferencesystem.cpp.
QgsProjectionFactors QgsCoordinateReferenceSystem::factors | ( | const QgsPoint & | point | ) | const |
Calculate various cartographic properties, such as scale factors, angular distortion and meridian convergence for the CRS at the given geodetic point (in geographic coordinates).
Depending on the underlying projection values will be calculated either numerically (default) or analytically. The function also calculates the partial derivatives of the given coordinate.
Definition at line 1505 of file qgscoordinatereferencesystem.cpp.
long QgsCoordinateReferenceSystem::findMatchingProj | ( | ) |
Walks the CRS databases (both system and user database) trying to match stored PROJ string to a database entry in order to fill in further pieces of information about CRS.
Definition at line 1944 of file qgscoordinatereferencesystem.cpp.
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static |
Creates a CRS from a given EPSG ID.
epsg | epsg CRS ID |
Definition at line 204 of file qgscoordinatereferencesystem.cpp.
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static |
Creates a CRS from a given OGC WMS-format Coordinate Reference System string.
ogcCrs | OGR compliant CRS definition, e.g., "EPSG:4326" |
Definition at line 197 of file qgscoordinatereferencesystem.cpp.
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static |
Creates a CRS from a proj style formatted string.
proj | proj format string |
Definition at line 223 of file qgscoordinatereferencesystem.cpp.
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static |
Creates a CRS from a proj style formatted string.
Definition at line 218 of file qgscoordinatereferencesystem.cpp.
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static |
Constructs a QgsCoordinateReferenceSystem from a PROJ PJ object.
The object must correspond to a PROJ CRS object.
Ownership of object is not transferred.
Definition at line 3194 of file qgscoordinatereferencesystem.cpp.
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static |
Creates a CRS from a specified QGIS SRS ID.
srsId | internal QGIS SRS ID |
Definition at line 237 of file qgscoordinatereferencesystem.cpp.
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static |
Creates a CRS from a WKT spatial ref sys definition string.
wkt | WKT for the desired spatial reference system. |
Definition at line 230 of file qgscoordinatereferencesystem.cpp.
QString QgsCoordinateReferenceSystem::geographicCrsAuthId | ( | ) | const |
Returns auth id of related geographic CRS.
Definition at line 3172 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::hasAxisInverted | ( | ) | const |
Returns whether the axis order is inverted for the CRS compared to the order east/north (longitude/latitude).
E.g. with WMS 1.3 the axis order for EPSG:4326 is north/east (latitude/longitude), i.e. inverted.
true
if CRS axis is invertedDefinition at line 823 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::hasVerticalAxis | ( | ) | const |
Returns true
if the CRS has a vertical axis.
Definition at line 3163 of file qgscoordinatereferencesystem.cpp.
QgsCoordinateReferenceSystem QgsCoordinateReferenceSystem::horizontalCrs | ( | ) | const |
Returns the horizontal CRS associated with this CRS object.
In the case of a compound CRS, this method will return just the horizontal CRS component.
An invalid CRS will be returned if the object does not contain a horizontal component.
Definition at line 3097 of file qgscoordinatereferencesystem.cpp.
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Clears the internal cache used to initialize QgsCoordinateReferenceSystem objects.
This should be called whenever the srs database has been modified in order to ensure that outdated CRS objects are not created.
If disableCache is true
then the inbuilt cache will be completely disabled. This argument is for internal use only.
Definition at line 3293 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::isDeprecated | ( | ) | const |
Returns true
if the CRS is considered deprecated.
Definition at line 1404 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::isDynamic | ( | ) | const |
Returns true
if the CRS is a dynamic CRS.
A dynamic CRS relies on a dynamic datum, that is a datum that is not plate-fixed.
Definition at line 1418 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::isGeographic | ( | ) | const |
Returns whether the CRS is a geographic CRS (using lat/lon coordinates)
true
if CRS is geographic, or false
if it is a projected CRS Definition at line 1413 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::isValid | ( | ) | const |
Returns whether this CRS is correctly initialized and usable.
Definition at line 1010 of file qgscoordinatereferencesystem.cpp.
Qgis::DistanceUnit QgsCoordinateReferenceSystem::mapUnits | ( | ) | const |
Returns the units for the projection used by the CRS.
Definition at line 1571 of file qgscoordinatereferencesystem.cpp.
Qgis::CrsDefinitionFormat QgsCoordinateReferenceSystem::nativeFormat | ( | ) | const |
Returns the native format for the CRS definition.
Definition at line 2411 of file qgscoordinatereferencesystem.cpp.
QgsProjOperation QgsCoordinateReferenceSystem::operation | ( | ) | const |
Returns information about the PROJ operation associated with the coordinate reference system, for example the projection method used by the CRS.
Definition at line 1544 of file qgscoordinatereferencesystem.cpp.
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Allows direct construction of QVariants from QgsCoordinateReferenceSystem.
Definition at line 273 of file qgscoordinatereferencesystem.h.
bool QgsCoordinateReferenceSystem::operator!= | ( | const QgsCoordinateReferenceSystem & | srs | ) | const |
Definition at line 2047 of file qgscoordinatereferencesystem.cpp.
QgsCoordinateReferenceSystem & QgsCoordinateReferenceSystem::operator= | ( | const QgsCoordinateReferenceSystem & | srs | ) |
Definition at line 133 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::operator== | ( | const QgsCoordinateReferenceSystem & | srs | ) | const |
Definition at line 2020 of file qgscoordinatereferencesystem.cpp.
long QgsCoordinateReferenceSystem::postgisSrid | ( | ) | const |
Returns PostGIS SRID for the CRS.
Definition at line 1223 of file qgscoordinatereferencesystem.cpp.
QString QgsCoordinateReferenceSystem::projectionAcronym | ( | ) | const |
Returns the projection acronym for the projection used by the CRS.
Definition at line 1272 of file qgscoordinatereferencesystem.cpp.
PJ * QgsCoordinateReferenceSystem::projObject | ( | ) | const |
Returns the underlying PROJ PJ object corresponding to the CRS, or nullptr
if the CRS is invalid.
This object is only valid for the lifetime of the QgsCoordinateReferenceSystem.
Definition at line 3189 of file qgscoordinatereferencesystem.cpp.
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Pushes a recently used CRS to the top of the recent CRS list.
Definition at line 3278 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::readXml | ( | const QDomNode & | node | ) |
Restores state from the given DOM node.
If it fails or if the node is empty, a default empty CRS will be returned.
node | The node from which state will be restored |
true
on success, false
on failure Definition at line 2102 of file qgscoordinatereferencesystem.cpp.
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Returns a list of recently used CRS.
Definition at line 3273 of file qgscoordinatereferencesystem.cpp.
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Returns a list of recently used projections.
Definition at line 3261 of file qgscoordinatereferencesystem.cpp.
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Removes a CRS from the list of recently used CRS.
Definition at line 3283 of file qgscoordinatereferencesystem.cpp.
long QgsCoordinateReferenceSystem::saveAsUserCrs | ( | const QString & | name, |
Qgis::CrsDefinitionFormat | nativeFormat = Qgis::CrsDefinitionFormat::Wkt |
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Saves the CRS as a new custom ("USER") CRS.
Returns the new CRS srsid(), or -1 if the CRS could not be saved.
The nativeFormat argument specifies the format to use when saving the CRS definition. FormatWkt is recommended as it is a lossless format.
Definition at line 2401 of file qgscoordinatereferencesystem.cpp.
void QgsCoordinateReferenceSystem::setCoordinateEpoch | ( | double | epoch | ) |
Sets the coordinate epoch, as a decimal year.
In a dynamic CRS (see isDynamic()), coordinates of a point on the surface of the Earth may change with time. To be unambiguous the coordinates must always be qualified with the epoch at which they are valid. The coordinate epoch is not necessarily the epoch at which the observation was collected.
Pedantically the coordinate epoch of an observation belongs to the observation, and not to the CRS, however it is often more practical to bind it to the CRS. The coordinate epoch should be specified for dynamic CRS (see isDynamic()).
epoch | Coordinate epoch as decimal year (e.g. 2021.3) |
Definition at line 1442 of file qgscoordinatereferencesystem.cpp.
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Sets custom function to force valid CRS.
Definition at line 2359 of file qgscoordinatereferencesystem.cpp.
void QgsCoordinateReferenceSystem::setNativeFormat | ( | Qgis::CrsDefinitionFormat | format | ) |
Sets the native format for the CRS definition.
Definition at line 2406 of file qgscoordinatereferencesystem.cpp.
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Make sure that ESRI WKT import is done properly.
This is required for proper shapefile CRS import when using gdal>= 1.9.
Definition at line 390 of file qgscoordinatereferencesystem.cpp.
void QgsCoordinateReferenceSystem::setValidationHint | ( | const QString & | html | ) |
Set user hint for validation.
Definition at line 2391 of file qgscoordinatereferencesystem.cpp.
long QgsCoordinateReferenceSystem::srsid | ( | ) | const |
Returns the internal CRS ID, if available.
Definition at line 1218 of file qgscoordinatereferencesystem.cpp.
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Update proj.4 parameters in our database from proj.4.
Definition at line 2645 of file qgscoordinatereferencesystem.cpp.
QgsCoordinateReferenceSystem QgsCoordinateReferenceSystem::toGeographicCrs | ( | ) | const |
Returns the geographic CRS associated with this CRS object.
May return an invalid CRS if the geographic CRS could not be determined.
Definition at line 3068 of file qgscoordinatereferencesystem.cpp.
QString QgsCoordinateReferenceSystem::toOgcUri | ( | ) | const |
Returns the crs as OGC URI (format: http://www.opengis.net/def/crs/OGC/1.3/CRS84) Returns an empty string on failure.
Definition at line 1607 of file qgscoordinatereferencesystem.cpp.
QString QgsCoordinateReferenceSystem::toOgcUrn | ( | ) | const |
Returns the crs as OGC URN (format: urn:ogc:def:crs:OGC:1.3:CRS84) Returns an empty string on failure.
Definition at line 1630 of file qgscoordinatereferencesystem.cpp.
QString QgsCoordinateReferenceSystem::toProj | ( | ) | const |
Returns a Proj string representation of this CRS.
If proj and ellps keys are found in the parameters, they will be stripped out and the projection and ellipsoid acronyms will be overridden with these.
Definition at line 1326 of file qgscoordinatereferencesystem.cpp.
QString QgsCoordinateReferenceSystem::toProj4 | ( | ) | const |
Returns a Proj string representation of this CRS.
If proj and ellps keys are found in the parameters, they will be stripped out and the projection and ellipsoid acronyms will be overridden with these.
Definition at line 1321 of file qgscoordinatereferencesystem.cpp.
QString QgsCoordinateReferenceSystem::toWkt | ( | Qgis::CrsWktVariant | variant = Qgis::CrsWktVariant::Wkt1Gdal , |
bool | multiline = false , |
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int | indentationWidth = 4 |
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) | const |
Returns a WKT representation of this CRS.
The variant argument specifies the formatting variant to use when creating the WKT string. This is only used on builds based on Proj >= 6, with earlier versions always using WKT1_GDAL.
If multiline is true
then a formatted multiline string will be returned, using the specified indentationWidth. This is only used on builds based on Proj >= 6.
Definition at line 2052 of file qgscoordinatereferencesystem.cpp.
Qgis::CrsType QgsCoordinateReferenceSystem::type | ( | ) | const |
Returns the type of the CRS.
Definition at line 1342 of file qgscoordinatereferencesystem.cpp.
void QgsCoordinateReferenceSystem::updateDefinition | ( | ) |
Updates the definition and parameters of the coordinate reference system to their latest values.
This only has an effect if the CRS is a user defined custom CRS, and the definition of that custom CRS has changed. In this case the parameters of the object (such as the proj and WKT string definitions, and other related properties) will be updated to reflect the current definition of the custom CRS.
Any objects which store CRS objects should connect to the QgsApplication::coordinateReferenceSystemRegistry()'s QgsCoordinateReferenceSystemRegistry::userCrsChanged() signal and call this method on their stored CRS objects whenever the signal is emitted in order to update these CRSes to their new definitions.
Definition at line 1654 of file qgscoordinatereferencesystem.cpp.
QString QgsCoordinateReferenceSystem::userFriendlyIdentifier | ( | Qgis::CrsIdentifierType | type = Qgis::CrsIdentifierType::MediumString | ) | const |
Returns a user friendly identifier for the CRS.
Depending on the format of the CRS, this may reflect the CRSes registered name, or for CRSes not saved in the database it may reflect the underlying WKT or Proj string definition of the CRS.
In most cases this is the best method to use when showing a friendly identifier for the CRS to a user.
Definition at line 1245 of file qgscoordinatereferencesystem.cpp.
void QgsCoordinateReferenceSystem::validate | ( | ) |
Perform some validation on this CRS.
If the CRS doesn't validate the default behavior settings for layers with unknown CRS will be consulted and acted on accordingly. By hell or high water this method will do its best to make sure that this CRS is valid - even if that involves resorting to a hard coded default of geocs:wgs84.
Definition at line 532 of file qgscoordinatereferencesystem.cpp.
QString QgsCoordinateReferenceSystem::validationHint | ( | ) | const |
Gets user hint for validation.
Definition at line 2396 of file qgscoordinatereferencesystem.cpp.
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Returns a list of all valid SRS IDs present in the CRS database.
Any of the returned values can be safely passed to fromSrsId() to create a new, valid QgsCoordinateReferenceSystem object.
Definition at line 141 of file qgscoordinatereferencesystem.cpp.
QgsCoordinateReferenceSystem QgsCoordinateReferenceSystem::verticalCrs | ( | ) | const |
Returns the vertical CRS associated with this CRS object.
In the case of a compound CRS, this method will return just the vertical CRS component.
An invalid CRS will be returned if the object does not contain a vertical component.
Definition at line 3130 of file qgscoordinatereferencesystem.cpp.
bool QgsCoordinateReferenceSystem::writeXml | ( | QDomNode & | node, |
QDomDocument & | doc | ||
) | const |
Stores state to the given Dom node in the given document.
node | The node in which state will be restored |
doc | The document in which state will be stored |
true
on success, false
on failure Definition at line 2222 of file qgscoordinatereferencesystem.cpp.
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Definition at line 3400 of file qgscoordinatereferencesystem.cpp.
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Definition at line 3453 of file qgscoordinatereferencesystem.cpp.
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Definition at line 3351 of file qgscoordinatereferencesystem.cpp.
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Definition at line 3449 of file qgscoordinatereferencesystem.cpp.
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Definition at line 1247 of file qgscoordinatereferencesystem.h.
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Definition at line 1221 of file qgscoordinatereferencesystem.h.
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Definition at line 1246 of file qgscoordinatereferencesystem.h.
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Definition at line 217 of file qgscoordinatereferencesystem.h.
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Definition at line 218 of file qgscoordinatereferencesystem.h.
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Definition at line 216 of file qgscoordinatereferencesystem.h.
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Definition at line 215 of file qgscoordinatereferencesystem.h.