QGIS API Documentation  3.9.0-Master (04f0879ed5)
Classes | Macros | Typedefs | Functions | Variables
qgis.h File Reference
#include <QMetaEnum>
#include <cfloat>
#include <memory>
#include <cmath>
#include "qgstolerance.h"
#include "qgis_core.h"
#include "qgis_sip.h"
Include dependency graph for qgis.h:

Go to the source code of this file.

Classes

class  Qgis
 The Qgis class provides global constants for use throughout the application. More...
 
class  QgsSignalBlocker< Object >
 RAII signal blocking class. More...
 

Macros

#define cast_to_fptr(f)   f
 
#define FALLTHROUGH
 
#define MAYBE_UNUSED
 
#define NODISCARD   Q_REQUIRED_RESULT
 
#define Q_NOWARN_DEPRECATED_POP
 
#define Q_NOWARN_DEPRECATED_PUSH
 
#define Q_NOWARN_UNREACHABLE_POP
 
#define Q_NOWARN_UNREACHABLE_PUSH
 
#define QGISEXTERN   extern "C"
 

Typedefs

typedef unsigned long long qgssize
 Qgssize is used instead of size_t, because size_t is stdlib type, unknown by SIP, and it would be hard to define size_t correctly in SIP. More...
 
typedef QMap< QString, QString > QgsStringMap
 

Functions

void CORE_EXPORT * qgsCalloc (size_t nmemb, size_t size)
 Allocates memory for an array of nmemb elements of size bytes each and returns a pointer to the allocated memory. More...
 
bool qgsDoubleNear (double a, double b, double epsilon=4 *std::numeric_limits< double >::epsilon())
 Compare two doubles (but allow some difference) More...
 
bool qgsDoubleNearSig (double a, double b, int significantDigits=10)
 Compare two doubles using specified number of significant digits. More...
 
QString qgsDoubleToString (double a, int precision=17)
 Returns a string representation of a double. More...
 
template<class T >
qgsEnumKeyToValue (const QString &key, const T &defaultValue)
 Returns the value corresponding to the given key of an enum. More...
 
template<class T >
const QMap< T, QString > qgsEnumMap ()
 Returns a map of all enum entries. More...
 
template<class T >
QString qgsEnumValueToKey (const T &value)
 Returns the value for the given key of an enum. More...
 
bool qgsFloatNear (float a, float b, float epsilon=4 *FLT_EPSILON)
 Compare two floats (but allow some difference) More...
 
void CORE_EXPORT qgsFree (void *ptr)
 Frees the memory space pointed to by ptr. More...
 
void CORE_EXPORT * qgsMalloc (size_t size)
 Allocates size bytes and returns a pointer to the allocated memory. More...
 
CORE_EXPORT double qgsPermissiveToDouble (QString string, bool &ok)
 Converts a string to a double in a permissive way, e.g., allowing for incorrect numbers of digits between thousand separators. More...
 
CORE_EXPORT int qgsPermissiveToInt (QString string, bool &ok)
 Converts a string to an integer in a permissive way, e.g., allowing for incorrect numbers of digits between thousand separators. More...
 
CORE_EXPORT qlonglong qgsPermissiveToLongLong (QString string, bool &ok)
 Converts a string to an qlonglong in a permissive way, e.g., allowing for incorrect numbers of digits between thousand separators. More...
 
double qgsRound (double number, int places)
 Returns a double number, rounded (as close as possible) to the specified number of places. More...
 
CORE_EXPORT bool qgsVariantEqual (const QVariant &lhs, const QVariant &rhs)
 Compares two QVariant values and returns whether they are equal, two NULL values are always treated as equal and 0 is not treated as equal with NULL. More...
 
CORE_EXPORT bool qgsVariantGreaterThan (const QVariant &lhs, const QVariant &rhs)
 Compares two QVariant values and returns whether the first is greater than the second. More...
 
CORE_EXPORT bool qgsVariantLessThan (const QVariant &lhs, const QVariant &rhs)
 Compares two QVariant values and returns whether the first is less than the second. More...
 
CORE_EXPORT QString qgsVsiPrefix (const QString &path)
 
CORE_EXPORT uint qHash (const QVariant &variant)
 Hash for QVariant. More...
 
template<class Object >
QgsSignalBlocker< Object > whileBlocking (Object *object)
 Temporarily blocks signals from a QObject while calling a single method from the object. More...
 

Variables

const double DEFAULT_LINE_WIDTH = 0.26
 
const double DEFAULT_POINT_SIZE = 2.0
 Magic number that determines the default point size for point symbols. More...
 
const double DEFAULT_SEGMENT_EPSILON = 1e-8
 Default snapping tolerance for segments. More...
 
CORE_EXPORT const QString GEO_EPSG_CRS_AUTHID
 Geographic coord sys from EPSG authority. More...
 
const long GEO_EPSG_CRS_ID = 4326
 Magic number for a geographic coord sys in EpsgCrsId ID format. More...
 
CORE_EXPORT const QString GEO_NONE
 Constant that holds the string representation for "No ellips/No CRS". More...
 
const long GEOCRS_ID = 3452
 Magic number for a geographic coord sys in QGIS srs.db tbl_srs.srs_id. More...
 
CORE_EXPORT const QString GEOPROJ4
 PROJ4 string that represents a geographic coord sys. More...
 
const long GEOSRID = 4326
 Magic number for a geographic coord sys in POSTGIS SRID. More...
 
CORE_EXPORT const QString GEOWKT
 Wkt string that represents a geographic coord sys. More...
 
CORE_EXPORT const QString PROJECT_SCALES
 
const int USER_CRS_START_ID = 100000
 Magick number that determines whether a projection crsid is a system (srs.db) or user (~/.qgis.qgis.db) defined projection. More...
 

Macro Definition Documentation

◆ cast_to_fptr

#define cast_to_fptr (   f)    f

Definition at line 158 of file qgis.h.

◆ FALLTHROUGH

#define FALLTHROUGH

Definition at line 666 of file qgis.h.

◆ MAYBE_UNUSED

#define MAYBE_UNUSED

Definition at line 701 of file qgis.h.

◆ NODISCARD

#define NODISCARD   Q_REQUIRED_RESULT

Definition at line 685 of file qgis.h.

◆ Q_NOWARN_DEPRECATED_POP

#define Q_NOWARN_DEPRECATED_POP

Definition at line 635 of file qgis.h.

◆ Q_NOWARN_DEPRECATED_PUSH

#define Q_NOWARN_DEPRECATED_PUSH

Definition at line 634 of file qgis.h.

◆ Q_NOWARN_UNREACHABLE_POP

#define Q_NOWARN_UNREACHABLE_POP

Definition at line 637 of file qgis.h.

◆ Q_NOWARN_UNREACHABLE_PUSH

#define Q_NOWARN_UNREACHABLE_PUSH

Definition at line 636 of file qgis.h.

◆ QGISEXTERN

#define QGISEXTERN   extern "C"

Definition at line 653 of file qgis.h.

Typedef Documentation

◆ qgssize

typedef unsigned long long qgssize

Qgssize is used instead of size_t, because size_t is stdlib type, unknown by SIP, and it would be hard to define size_t correctly in SIP.

Currently used "unsigned long long" was introduced in C++11 (2011) but it was supported already before C++11 on common platforms. "unsigned long long int" gives syntax error in SIP. KEEP IN SYNC WITH qgssize defined in SIP!

Definition at line 606 of file qgis.h.

◆ QgsStringMap

typedef QMap<QString, QString> QgsStringMap

Definition at line 597 of file qgis.h.

Function Documentation

◆ qgsCalloc()

void CORE_EXPORT* qgsCalloc ( size_t  nmemb,
size_t  size 
)

Allocates memory for an array of nmemb elements of size bytes each and returns a pointer to the allocated memory.

Works like C calloc() but prints debug message by QgsLogger if allocation fails.

Parameters
nmembnumber of elements
sizesize of element in bytes

Definition at line 134 of file qgis.cpp.

◆ qgsDoubleNear()

bool qgsDoubleNear ( double  a,
double  b,
double  epsilon = 4 * std::numeric_limits<double>::epsilon() 
)
inline

Compare two doubles (but allow some difference)

Parameters
afirst double
bsecond double
epsilonmaximum difference allowable between doubles

Definition at line 265 of file qgis.h.

◆ qgsDoubleNearSig()

bool qgsDoubleNearSig ( double  a,
double  b,
int  significantDigits = 10 
)
inline

Compare two doubles using specified number of significant digits.

Definition at line 290 of file qgis.h.

◆ qgsDoubleToString()

QString qgsDoubleToString ( double  a,
int  precision = 17 
)
inline

Returns a string representation of a double.

Parameters
adouble value
precisionnumber of decimal places to retain

Definition at line 225 of file qgis.h.

◆ qgsEnumKeyToValue()

template<class T >
T qgsEnumKeyToValue ( const QString &  key,
const T &  defaultValue 
)

Returns the value corresponding to the given key of an enum.

If the key is invalid, it will return the defaultValue.

Since
QGIS 3.6

Definition at line 448 of file qgis.h.

◆ qgsEnumMap()

template<class T >
const QMap<T, QString> qgsEnumMap ( )

Returns a map of all enum entries.

The map has the enum values (int) as keys and the enum keys (QString) as values. The enum must have been declared using Q_ENUM or Q_FLAG.

Definition at line 419 of file qgis.h.

◆ qgsEnumValueToKey()

template<class T >
QString qgsEnumValueToKey ( const T &  value)

Returns the value for the given key of an enum.

Since
QGIS 3.6

Definition at line 436 of file qgis.h.

◆ qgsFloatNear()

bool qgsFloatNear ( float  a,
float  b,
float  epsilon = 4 * FLT_EPSILON 
)
inline

Compare two floats (but allow some difference)

Parameters
afirst float
bsecond float
epsilonmaximum difference allowable between floats

Definition at line 280 of file qgis.h.

◆ qgsFree()

void CORE_EXPORT qgsFree ( void *  ptr)

Frees the memory space pointed to by ptr.

Works like C free().

Parameters
ptrpointer to memory space

Definition at line 149 of file qgis.cpp.

◆ qgsMalloc()

void CORE_EXPORT* qgsMalloc ( size_t  size)

Allocates size bytes and returns a pointer to the allocated memory.

Works like C malloc() but prints debug message by QgsLogger if allocation fails.

Parameters
sizesize in bytes

Definition at line 119 of file qgis.cpp.

◆ qgsPermissiveToDouble()

CORE_EXPORT double qgsPermissiveToDouble ( QString  string,
bool &  ok 
)

Converts a string to a double in a permissive way, e.g., allowing for incorrect numbers of digits between thousand separators.

Parameters
stringstring to convert
okwill be set to true if conversion was successful
Returns
string converted to double if possible
See also
permissiveToInt
Since
QGIS 2.9

Definition at line 98 of file qgis.cpp.

◆ qgsPermissiveToInt()

CORE_EXPORT int qgsPermissiveToInt ( QString  string,
bool &  ok 
)

Converts a string to an integer in a permissive way, e.g., allowing for incorrect numbers of digits between thousand separators.

Parameters
stringstring to convert
okwill be set to true if conversion was successful
Returns
string converted to int if possible
See also
permissiveToDouble
Since
QGIS 2.9

Definition at line 105 of file qgis.cpp.

◆ qgsPermissiveToLongLong()

CORE_EXPORT qlonglong qgsPermissiveToLongLong ( QString  string,
bool &  ok 
)

Converts a string to an qlonglong in a permissive way, e.g., allowing for incorrect numbers of digits between thousand separators.

Parameters
stringstring to convert
okwill be set to true if conversion was successful
Returns
string converted to int if possible
See also
permissiveToInt
Since
QGIS 3.4

Definition at line 112 of file qgis.cpp.

◆ qgsRound()

double qgsRound ( double  number,
int  places 
)
inline

Returns a double number, rounded (as close as possible) to the specified number of places.

Since
QGIS 3.0

Definition at line 313 of file qgis.h.

◆ qgsVariantEqual()

CORE_EXPORT bool qgsVariantEqual ( const QVariant &  lhs,
const QVariant &  rhs 
)

Compares two QVariant values and returns whether they are equal, two NULL values are always treated as equal and 0 is not treated as equal with NULL.

Parameters
lhsfirst value
rhssecond value
Returns
true if values are equal

Definition at line 298 of file qgis.cpp.

◆ qgsVariantGreaterThan()

CORE_EXPORT bool qgsVariantGreaterThan ( const QVariant &  lhs,
const QVariant &  rhs 
)

Compares two QVariant values and returns whether the first is greater than the second.

Useful for sorting lists of variants, correctly handling sorting of the various QVariant data types (such as strings, numeric values, dates and times)

See also
qgsVariantLessThan()

Definition at line 222 of file qgis.cpp.

◆ qgsVariantLessThan()

CORE_EXPORT bool qgsVariantLessThan ( const QVariant &  lhs,
const QVariant &  rhs 
)

Compares two QVariant values and returns whether the first is less than the second.

Useful for sorting lists of variants, correctly handling sorting of the various QVariant data types (such as strings, numeric values, dates and times)

Invalid < NULL < Values

See also
qgsVariantGreaterThan()

Definition at line 154 of file qgis.cpp.

◆ qgsVsiPrefix()

CORE_EXPORT QString qgsVsiPrefix ( const QString &  path)

Definition at line 227 of file qgis.cpp.

◆ qHash()

CORE_EXPORT uint qHash ( const QVariant &  variant)

Hash for QVariant.

Definition at line 252 of file qgis.cpp.

◆ whileBlocking()

template<class Object >
QgsSignalBlocker<Object> whileBlocking ( Object *  object)
inline

Temporarily blocks signals from a QObject while calling a single method from the object.

Usage: whileBlocking( checkBox )->setChecked( true ); whileBlocking( spinBox )->setValue( 50 );

No signals will be emitted when calling these methods.

See also
QgsSignalBlocker
Note
not available in Python bindings
Since
QGIS 2.16

Definition at line 212 of file qgis.h.

Variable Documentation

◆ DEFAULT_LINE_WIDTH

const double DEFAULT_LINE_WIDTH = 0.26

Definition at line 580 of file qgis.h.

◆ DEFAULT_POINT_SIZE

const double DEFAULT_POINT_SIZE = 2.0

Magic number that determines the default point size for point symbols.

Definition at line 579 of file qgis.h.

◆ DEFAULT_SEGMENT_EPSILON

const double DEFAULT_SEGMENT_EPSILON = 1e-8

Default snapping tolerance for segments.

Definition at line 583 of file qgis.h.

◆ GEO_EPSG_CRS_AUTHID

CORE_EXPORT const QString GEO_EPSG_CRS_AUTHID

Geographic coord sys from EPSG authority.

Definition at line 70 of file qgis.cpp.

◆ GEO_EPSG_CRS_ID

const long GEO_EPSG_CRS_ID = 4326

Magic number for a geographic coord sys in EpsgCrsId ID format.

Definition at line 562 of file qgis.h.

◆ GEO_NONE

CORE_EXPORT const QString GEO_NONE

Constant that holds the string representation for "No ellips/No CRS".

Definition at line 72 of file qgis.cpp.

◆ GEOCRS_ID

const long GEOCRS_ID = 3452

Magic number for a geographic coord sys in QGIS srs.db tbl_srs.srs_id.

Definition at line 560 of file qgis.h.

◆ GEOPROJ4

CORE_EXPORT const QString GEOPROJ4

PROJ4 string that represents a geographic coord sys.

Definition at line 51 of file qgis.cpp.

◆ GEOSRID

const long GEOSRID = 4326

Magic number for a geographic coord sys in POSTGIS SRID.

Definition at line 558 of file qgis.h.

◆ GEOWKT

CORE_EXPORT const QString GEOWKT

Wkt string that represents a geographic coord sys.

Since
QGIS GEOWkt

Definition at line 53 of file qgis.cpp.

◆ PROJECT_SCALES

CORE_EXPORT const QString PROJECT_SCALES

Definition at line 66 of file qgis.cpp.

◆ USER_CRS_START_ID

const int USER_CRS_START_ID = 100000

Magick number that determines whether a projection crsid is a system (srs.db) or user (~/.qgis.qgis.db) defined projection.

Definition at line 569 of file qgis.h.