Class: QgsApplication

Extends QApplication to provide access to QGIS specific resources such as theme paths, database paths etc.

This is a subclass of QApplication and should be instantiated in place of QApplication. Most methods are static in keeping with the design of QApplication.

This class hides platform-specific path information and provides a portable way of referencing specific files and directories. Ideally, hard-coded paths should appear only here and not in other modules so that platform-conditional code is minimized and paths are easier to change due to centralization.

Class Hierarchy

Base classes

QApplication
QGuiApplication
QCoreApplication
QObject

Methods

collectTranslatableObjects	Emits the signal to collect all the strings of .qgs to be included in ts file
maxConcurrentConnectionsPerPool	The maximum number of concurrent connections per connections pool.
translation	Returns the current application translation locale code

Virtual Methods

In PyQGIS, only methods marked as virtual can be safely overridden in a Python subclass of QgsApplication. See the FAQ for more details.

event	Watch for QFileOpenEvent.
notify	Catch exceptions when sending event to receiver.

Static Methods

absolutePathToRelativePath	Converts absolute path to path relative to target
actionScopeRegistry	Returns the action scope registry.
activeThemePath	Returns the path to the currently active theme directory.
annotationItemRegistry	Returns the application's annotation item registry, used for annotation item types.
appIconPath	Gets application icon
applicationFullName	Returns the QGIS application full name.
applyGdalSkippedDrivers	Apply the skipped drivers list to gdal
authConfigurationStorageRegistry	Returns the application's authentication configuration storage registry
authManager	Returns the application's authentication manager instance
authorsFilePath	Returns the path to the authors file.
bookmarkManager	Returns the application's bookmark manager, used for storing installation-wide bookmarks.
buildOutputPath	Returns path to the build output directory.
buildSourcePath	Returns path to the source directory.
calloutRegistry	Returns the application's callout registry, used for managing callout types.
classificationMethodRegistry	Returns the application's classification methods registry, used in graduated renderer
colorSchemeRegistry	Returns the application's color scheme registry, used for managing color schemes.
connectionRegistry	Returns the application's connection registry, used for managing saved data provider connections.
contributorsFilePath	Returns the path to the contributors file.
coordinateReferenceSystemRegistry	Returns the application's coordinate reference system (CRS) registry, which handles known CRS definitions (including user-defined CRSes).
createDatabase	initialize qgis.db
createThemeFolder	Create the users theme folder
customVariables	Custom expression variables for this application.
dataItemProviderRegistry	Returns the application's data item provider registry, which keeps a list of data item providers that may add items to the browser tree.
databaseQueryLog	Returns the database query log.
defaultStyleModel	Returns a shared QgsStyleModel containing the default style library (see QgsStyle.defaultStyle()).
defaultStylePath	Returns the path to default style (works as a starting point).
defaultThemePath	Returns the path to the default theme directory.
defaultThemesFolder	Returns the path to default themes folder from install (works as a starting point).
deferredSkippedGdalDrivers	Returns the list of gdal drivers that have been disabled in the current session, and thus, for safety, should not be disabled right now, but at the next application restart.
developersMapFilePath	Returns the path to the developers map file.
donorsFilePath	Returns the path to the donors file.
endian	Returns whether this machine uses big or little endian
exitQgis	deletes provider registry and map layer registry
externalStorageRegistry	Returns registry of available external storage implementations.
fieldFormatterRegistry	Gets the registry of available field formatters.
fontManager	Returns the application font manager, which manages available fonts and font installation for the QGIS instance.
getThemeCursor	Helper to get a theme cursor.
getThemeIcon	Helper to get a theme icon.
getThemePixmap	Helper to get a theme icon as a pixmap.
gpsBabelFormatRegistry	Returns the application's GPSBabel format registry, used for managing GPSBabel formats.
gpsConnectionRegistry	Returns the application's GPS connection registry, used for managing GPS connections.
i18nPath	Returns the path to the translation directory.
iconPath	Returns path to the desired icon file.
iconsPath	Returns the path to the icons image directory.
imageCache	Returns the application's image cache, used for caching resampled versions of raster images.
initQgis	loads providers
instance	Returns the singleton instance of the QgsApplication.
isRunningFromBuildDir	Indicates whether running from build directory (not installed)
labelingEngineRuleRegistry	Gets the registry of available labeling engine rules.
layerMetadataProviderRegistry	Returns registry of available layer metadata provider implementations.
layoutItemRegistry	Returns the application's layout item registry, used for layout item types.
layoutTemplatePaths	Returns the paths to layout template directories.
libexecPath	Returns the path with utility executables (help viewer, crssync, ...)
libraryPath	Returns the path containing qgis_core, qgis_gui, qgispython (and other) libraries
licenceFilePath	Returns the path to the licence file.
locale	Returns the QGIS locale.
localizedDataPathRegistry	Returns the registry of data repositories These are used as paths for basemaps, logos, etc.
maxThreads	Gets maximum concurrent thread count
messageLog	Returns the application's message log.
metadataPath	Returns the path to the metadata directory.
networkContentFetcherRegistry	Returns the application's network content registry used for fetching temporary files during QGIS session
nullRepresentation	Returns the string used to represent the value NULL throughout QGIS.
numericFormatRegistry	Gets the registry of available numeric formats.
osName	Returns a string name of the operating system QGIS is running on.
pageSizeRegistry	Returns the application's page size registry, used for managing layout page sizes.
paintEffectRegistry	Returns the application's paint effect registry, used for managing paint effects.
pkgDataPath	Returns the common root path of all application data directories.
platform	Returns the QGIS platform name, e.g., "desktop", "server", "qgis_process" or "external" (for external CLI scripts).
pluginLayerRegistry	Returns the application's plugin layer registry, used for managing plugin layer types.
pluginPath	Returns the path to the application plugin directory.
pointCloudRendererRegistry	Returns the application's point cloud renderer registry, used for managing point cloud layer 2D renderers.
prefixPath	Returns the path to the application prefix directory.
processingRegistry	Returns the application's processing registry, used for managing processing providers, algorithms, and various parameters and outputs.
profileSourceRegistry	Returns registry of available profile source implementations.
profiler	Returns the application runtime profiler.
projectStorageRegistry	Returns registry of available project storage implementations.
qgisAuthDatabaseFilePath	Returns the path to the user authentication database file: qgis-auth.db.
qgisAuthDatabaseUri	Returns the URI to the user authentication database.
qgisMasterDatabaseFilePath	Returns the path to the master qgis.db file.
qgisSettingsDirPath	Returns the path to the settings directory in user's home dir
qgisUserDatabaseFilePath	Returns the path to the user qgis.db file.
qmlImportPath	Returns the path where QML components are installed for QGIS Quick library.
recentStyleHandler	Returns the handler for recently used style items.
registerGdalDriversFromSettings	Register gdal drivers, excluding the ones mentioned in "gdal/skipList" setting.
registerOgrDrivers	Register OGR drivers ensuring this only happens once.
relativePathToAbsolutePath	Converts path relative to target to an absolute path
renderer3DRegistry	Returns registry of available 3D renderers.
rendererRegistry	Returns the application's renderer registry, used for managing vector layer renderers.
reportStyleSheet	Returns a css style sheet for reports, the styleSheetType argument determines what type of stylesheet is supported by the widget.
resolvePkgPath	Calculate the application pkg path
restoreGdalDriver	Sets the GDAL_SKIP environment variable to exclude the specified driver and then calls GDALDriverManager.AutoSkipDrivers() to unregister it.
scaleBarRendererRegistry	Gets the registry of available scalebar renderers.
scaleIconSize	Scales an icon size to compensate for display pixel density, making the icon size hi-dpi friendly, whilst still resulting in pixel-perfect sizes for low-dpi displays.
sensorRegistry	Returns the application's sensor registry, used for sensor types.
serverResourcesPath	Returns the path to the server resources directory.
setAuthDatabaseDirPath	Alters authentication data base directory path - used by 3rd party apps
setCustomVariable	Set a single custom expression variable.
setCustomVariables	Custom expression variables for this application.
setDefaultSvgPaths	Alters default svg paths - used by 3rd party apps.
setFileOpenEventReceiver	Sets the FileOpen event receiver
setLocale	Sets the QGIS locale - used mainly by 3rd party apps and tests.
setMaxThreads	Set maximum concurrent thread count
setNullRepresentation	Sets the string used to represent the value NULL throughout QGIS.
setPkgDataPath	Alters pkg data path - used by 3rd party apps
setPluginPath	Alters plugin path - used by 3rd party apps
setPrefixPath	Alters prefix path - used by 3rd party apps
setSkippedGdalDrivers	Sets the list of gdal drivers that should be disabled (skippedGdalDrivers), but excludes for now the ones defines in deferredSkippedGdalDrivers.
setSvgPaths	Sets the paths to svg directories and invalidates the svg path list cache.
setThemeName	Set the active theme to the specified theme.
setTranslation	Set translation locale code
setUITheme	Set the current UI theme used to style the interface.
settingsRegistryCore	Returns the application's settings registry, used for managing application settings.
shortNameRegularExpression	Returns the short name regular expression for line edit validator
showSettings	Convenience function to get a summary of the paths used in this application instance useful for debugging mainly.
skipGdalDriver	Sets the GDAL_SKIP environment variable to include the specified driver and then calls GDALDriverManager.AutoSkipDrivers() to unregister it.
skippedGdalDrivers	Returns the list of gdal drivers that should be skipped (based on GDAL_SKIP environment variable)
sourceCache	Returns the application's source cache, used for caching embedded and remote source strings as local files
splashPath	Returns the path to the splash screen image directory.
sponsorsFilePath	Returns the path to the sponsors file.
srsDatabaseFilePath	Returns the path to the srs.db file.
svgCache	Returns the application's SVG cache, used for caching SVG images and handling parameter replacement within SVG files.
svgPaths	Returns the paths to svg directories.
symbol3DRegistry	Returns registry of available 3D symbols.
symbolLayerRegistry	Returns the application's symbol layer registry, used for managing symbol layers.
systemEnvVars	Returns the system environment variables passed to application.
systemMemorySizeMb	Returns the size of the system memory (RAM) in megabytes.
taskManager	Returns the application's task manager, used for managing application wide background task handling.
themeName	Set the active theme to the specified theme.
tiledSceneRendererRegistry	Returns the application's tiled scene renderer registry, used for managing tiled scene layer 2D renderers.
translatorsFilePath	Returns the path to the sponsors file.
uiThemes	All themes found in ~/.qgis3/themes folder.
userFullName	Returns the user's operating system login account full display name.
userLoginName	Returns the user's operating system login account name.
userStylePath	Returns the path to user's style.
userThemesFolder	Returns the path to user's themes folder
validityCheckRegistry	Returns the application's validity check registry, used for managing validity checks.

Signals

customVariablesChanged	Emitted whenever a custom global variable changes.
localeChanged	Emitted when project locale has been changed.
nullRepresentationChanged	Emitted when the string representing the NULL value is changed.
requestForTranslatableObjects	Emitted when project strings which require translation are being collected for inclusion in a .ts file.

Attributes

CapturePoint
CrossHair
Identify
NDR
QGIS_APPLICATION_NAME
QGIS_ORGANIZATION_DOMAIN
QGIS_ORGANIZATION_NAME
Qt
Sampler
Select
WebBrowser
XDR
ZoomIn
ZoomOut

class qgis.core.QgsApplication

Bases: QApplication

__init__(argv: List, GUIenabled: bool, profileFolder: str | None = '', platformName: str | None = '')

Constructor for QgsApplication.

Parameters:

• argv (List) – command line arguments

• GUIenabled (bool) – set to True if a GUI application is required, or False for a console only application

• profileFolder (Optional[str] = '') – optional string representing the profile to load at startup

• platformName (Optional[str] = '') – the QGIS platform name, e.g., “desktop”, “server”, “qgis_process” or “external” (for external CLI scripts)

CapturePoint = 4

CrossHair = 3

class Cursor

Bases: int

Identify = 2

NDR = 1

QGIS_APPLICATION_NAME = 'QGIS3'

QGIS_ORGANIZATION_DOMAIN = 'qgis.org'

QGIS_ORGANIZATION_NAME = 'QGIS'

Qt = 0

Sampler = 6

Select = 5

class StyleSheetType

Bases: int

WebBrowser = 1

XDR = 0

ZoomIn = 0

ZoomOut = 1

static absolutePathToRelativePath(apath: str | None, targetPath: str | None) → str

Converts absolute path to path relative to target

Parameters:

• apath (Optional[str])

• targetPath (Optional[str])

Return type:

str

static actionScopeRegistry() → QgsActionScopeRegistry | None

Returns the action scope registry.

Return type:

Optional[QgsActionScopeRegistry]

static activeThemePath() → str

Returns the path to the currently active theme directory.

Return type:

str

static annotationItemRegistry() → QgsAnnotationItemRegistry | None

Returns the application’s annotation item registry, used for annotation item types.

Added in version 3.16.

Return type:

Optional[QgsAnnotationItemRegistry]

static appIconPath() → str

Gets application icon

Return type:

str

static applicationFullName() → str

Returns the QGIS application full name.

It can be defined by the environment variable QGIS_APPLICATION_FULL_NAME or the /qgis/application_full_name in the QGIS config file.

By default it is equal to platform()

See also

platform()

Added in version 3.30.

Return type:

str

static applyGdalSkippedDrivers()

Apply the skipped drivers list to gdal

See also

skipGdalDriver()

See also

restoreGdalDriver()

See also

skippedGdalDrivers()

static authConfigurationStorageRegistry() → QgsAuthConfigurationStorageRegistry | None

Returns the application’s authentication configuration storage registry

Added in version 3.40.

Return type:

Optional[QgsAuthConfigurationStorageRegistry]

static authManager() → QgsAuthManager | None

Returns the application’s authentication manager instance

Note

this can be None if called before initQgis

See also

initQgis()

Return type:

Optional[QgsAuthManager]

static authorsFilePath() → str

Returns the path to the authors file.

Return type:

str

static bookmarkManager() → QgsBookmarkManager | None

Returns the application’s bookmark manager, used for storing installation-wide bookmarks.

Added in version 3.10.

Return type:

Optional[QgsBookmarkManager]

static buildOutputPath() → str

Returns path to the build output directory. Valid only when running from build directory

Return type:

str

static buildSourcePath() → str

Returns path to the source directory. Valid only when running from build directory

Return type:

str

static calloutRegistry() → QgsCalloutRegistry | None

Returns the application’s callout registry, used for managing callout types.

Added in version 3.10.

Return type:

Optional[QgsCalloutRegistry]

static classificationMethodRegistry() → QgsClassificationMethodRegistry | None

Returns the application’s classification methods registry, used in graduated renderer

Added in version 3.10.

Return type:

Optional[QgsClassificationMethodRegistry]

collectTranslatableObjects(self, translationContext: QgsTranslationContext | None)

Emits the signal to collect all the strings of .qgs to be included in ts file

Added in version 3.4.

Parameters:

translationContext (Optional[QgsTranslationContext])

static colorSchemeRegistry() → QgsColorSchemeRegistry | None

Returns the application’s color scheme registry, used for managing color schemes.

Return type:

Optional[QgsColorSchemeRegistry]

static connectionRegistry() → QgsConnectionRegistry | None

Returns the application’s connection registry, used for managing saved data provider connections.

Added in version 3.14.

Return type:

Optional[QgsConnectionRegistry]

static contributorsFilePath() → str

Returns the path to the contributors file. Contributors are people who have submitted patches but don’t have commit access.

Return type:

str

static coordinateReferenceSystemRegistry() → QgsCoordinateReferenceSystemRegistry | None

Returns the application’s coordinate reference system (CRS) registry, which handles known CRS definitions (including user-defined CRSes).

Added in version 3.18.

Return type:

Optional[QgsCoordinateReferenceSystemRegistry]

static createDatabase(errorMessage: str | None | None = '') → bool

initialize qgis.db

Parameters:

errorMessage (Optional[Optional[str]] = '')

Return type:

bool

static createThemeFolder() → bool

Create the users theme folder

Return type:

bool

static customVariables() → Dict[str, Any]

Custom expression variables for this application. This does not include generated variables (like system name, user name etc.)

See also

QgsExpressionContextUtils.globalScope()

Return type:

Dict[str, Any]

signal customVariablesChanged

Emitted whenever a custom global variable changes.

static dataItemProviderRegistry() → QgsDataItemProviderRegistry | None

Returns the application’s data item provider registry, which keeps a list of data item providers that may add items to the browser tree.

Return type:

Optional[QgsDataItemProviderRegistry]

static databaseQueryLog() → QgsDatabaseQueryLog | None

Returns the database query log.

Added in version 3.24.

Return type:

Optional[QgsDatabaseQueryLog]

static defaultStyleModel() → QgsStyleModel | None

Returns a shared QgsStyleModel containing the default style library (see QgsStyle.defaultStyle()).

Using this shared model instead of creating a new QgsStyleModel improves performance.

Added in version 3.10.

Return type:

Optional[QgsStyleModel]

static defaultStylePath() → str

Returns the path to default style (works as a starting point).

Return type:

str

static defaultThemePath() → str

Returns the path to the default theme directory.

Return type:

str

static defaultThemesFolder() → str

Returns the path to default themes folder from install (works as a starting point).

Return type:

str

static deferredSkippedGdalDrivers() → List[str]

Returns the list of gdal drivers that have been disabled in the current session, and thus, for safety, should not be disabled right now, but at the next application restart.

Added in version 3.10.

Return type:

List[str]

static developersMapFilePath() → str

Returns the path to the developers map file. The developers map was created by using leaflet framework, it shows the contributors.json file.

Return type:

str

static donorsFilePath() → str

Returns the path to the donors file.

Return type:

str

static endian() → QgsApplication.endian_t

Returns whether this machine uses big or little endian

Return type:

QgsApplication.endian_t

class endian_t

Bases: int

virtual event(self, event: QEvent | None) → bool

Watch for QFileOpenEvent.

Parameters:

event (Optional[QEvent])

Return type:

bool

static exitQgis()

deletes provider registry and map layer registry

static externalStorageRegistry() → QgsExternalStorageRegistry | None

Returns registry of available external storage implementations.

Added in version 3.20.

Return type:

Optional[QgsExternalStorageRegistry]

static fieldFormatterRegistry() → QgsFieldFormatterRegistry | None

Gets the registry of available field formatters.

Return type:

Optional[QgsFieldFormatterRegistry]

static fontManager() → QgsFontManager | None

Returns the application font manager, which manages available fonts and font installation for the QGIS instance.

Added in version 3.28.

Return type:

Optional[QgsFontManager]

static getThemeCursor(cursor: QgsApplication.Cursor) → QCursor

Helper to get a theme cursor. It will fall back to the default theme if the active theme does not have the required icon. Cursors are automatically scaled to look like a 16px cursor on 96dpi screens.

Parameters:

cursor (QgsApplication.Cursor)

Return type:

QCursor

static getThemeIcon(name: str | None, fillColor: QColor | Qt.GlobalColor = QColor(), strokeColor: QColor | Qt.GlobalColor = QColor()) → QIcon

Helper to get a theme icon. It will fall back to the default theme if the active theme does not have the required icon.

Since QGIS 3.20, the optional fillColor and strokeColor arguments can be used to control the color of parameter based SVG icons.

Parameters:

• name (Optional[str])

• fillColor (Union[QColor, Qt.GlobalColor] = QColor())

• strokeColor (Union[QColor, Qt.GlobalColor] = QColor())

Return type:

QIcon

static getThemePixmap(name: str | None, foreColor: QColor | Qt.GlobalColor = QColor(), backColor: QColor | Qt.GlobalColor = QColor(), size: int = 16) → QPixmap

Helper to get a theme icon as a pixmap. It will fall back to the default theme if the active theme does not have the required icon.

If foreColor or backColor are specified, then these colors will be used for parametrized colors in SVG files wherever available. If colors are specified then the size argument also must be set.

Parameters:

• name (Optional[str])

• foreColor (Union[QColor, Qt.GlobalColor] = QColor())

• backColor (Union[QColor, Qt.GlobalColor] = QColor())

• size (int = 16)

Return type:

QPixmap

static gpsBabelFormatRegistry() → QgsBabelFormatRegistry | None

Returns the application’s GPSBabel format registry, used for managing GPSBabel formats.

Added in version 3.22.

Return type:

Optional[QgsBabelFormatRegistry]

static gpsConnectionRegistry() → QgsGpsConnectionRegistry | None

Returns the application’s GPS connection registry, used for managing GPS connections.

Return type:

Optional[QgsGpsConnectionRegistry]

static i18nPath() → str

Returns the path to the translation directory.

Return type:

str

static iconPath(iconFile: str | None) → str

Returns path to the desired icon file. First it tries to use the active theme path, then default theme path

Parameters:

iconFile (Optional[str])

Return type:

str

static iconsPath() → str

Returns the path to the icons image directory.

Return type:

str

static imageCache() → QgsImageCache | None

Returns the application’s image cache, used for caching resampled versions of raster images.

See also

svgCache()

Added in version 3.6.

Return type:

Optional[QgsImageCache]

static initQgis()

loads providers

static instance() → QgsApplication | None

Returns the singleton instance of the QgsApplication.

Return type:

Optional[QgsApplication]

static isRunningFromBuildDir() → bool

Indicates whether running from build directory (not installed)

Return type:

bool

static labelingEngineRuleRegistry() → QgsLabelingEngineRuleRegistry | None

Gets the registry of available labeling engine rules.

Added in version 3.40.

Return type:

Optional[QgsLabelingEngineRuleRegistry]

static layerMetadataProviderRegistry() → QgsLayerMetadataProviderRegistry | None

Returns registry of available layer metadata provider implementations.

Added in version 3.28.

Return type:

Optional[QgsLayerMetadataProviderRegistry]

static layoutItemRegistry() → QgsLayoutItemRegistry | None

Returns the application’s layout item registry, used for layout item types.

Return type:

Optional[QgsLayoutItemRegistry]

static layoutTemplatePaths() → List[str]

Returns the paths to layout template directories.

Return type:

List[str]

static libexecPath() → str

Returns the path with utility executables (help viewer, crssync, …)

Return type:

str

static libraryPath() → str

Returns the path containing qgis_core, qgis_gui, qgispython (and other) libraries

Return type:

str

static licenceFilePath() → str

Returns the path to the licence file.

Return type:

str

static locale() → str

Returns the QGIS locale.

Return type:

str

signal localeChanged

Emitted when project locale has been changed.

Added in version 3.22.2.

static localizedDataPathRegistry() → QgsLocalizedDataPathRegistry | None

Returns the registry of data repositories These are used as paths for basemaps, logos, etc. which can be referenced differently across work stations.

See also

QgsLocalizedDataPathRegistry

Added in version 3.14.

Return type:

Optional[QgsLocalizedDataPathRegistry]

maxConcurrentConnectionsPerPool(self) → int

The maximum number of concurrent connections per connections pool.

Note

QGIS may in some situations allocate more than this amount of connections to avoid deadlocks.

Added in version 3.4.

Return type:

int

static maxThreads() → int

Gets maximum concurrent thread count

Return type:

int

static messageLog() → QgsMessageLog | None

Returns the application’s message log.

Return type:

Optional[QgsMessageLog]

static metadataPath() → str

Returns the path to the metadata directory.

Return type:

str

static networkContentFetcherRegistry() → QgsNetworkContentFetcherRegistry | None

Returns the application’s network content registry used for fetching temporary files during QGIS session

Added in version 3.2.

Return type:

Optional[QgsNetworkContentFetcherRegistry]

virtual notify(self, receiver: QObject | None, event: QEvent | None) → bool

Catch exceptions when sending event to receiver.

Parameters:

• receiver (Optional[QObject])

• event (Optional[QEvent])

Return type:

bool

static nullRepresentation() → str

Returns the string used to represent the value NULL throughout QGIS.

Note

In general, when passing values around, prefer to use an invalid QVariant. The nullRepresentation() value should only be used in the final presentation step when showing values in a widget or sending it to a web browser.

See also

setNullRepresentation()

See also

nullRepresentationChanged()

Return type:

str

signal nullRepresentationChanged

Emitted when the string representing the NULL value is changed.

See also

setNullRepresentation()

See also

nullRepresentation()

static numericFormatRegistry() → QgsNumericFormatRegistry | None

Gets the registry of available numeric formats.

Added in version 3.12.

Return type:

Optional[QgsNumericFormatRegistry]

static osName() → str

Returns a string name of the operating system QGIS is running on.

See also

platform()

Return type:

str

static pageSizeRegistry() → QgsPageSizeRegistry | None

Returns the application’s page size registry, used for managing layout page sizes.

Return type:

Optional[QgsPageSizeRegistry]

static paintEffectRegistry() → QgsPaintEffectRegistry | None

Returns the application’s paint effect registry, used for managing paint effects.

Return type:

Optional[QgsPaintEffectRegistry]

static pkgDataPath() → str

Returns the common root path of all application data directories.

Return type:

str

static platform() → str

Returns the QGIS platform name, e.g., “desktop”, “server”, “qgis_process” or “external” (for external CLI scripts).

See also

osName()

Return type:

str

static pluginLayerRegistry() → QgsPluginLayerRegistry | None

Returns the application’s plugin layer registry, used for managing plugin layer types.

Return type:

Optional[QgsPluginLayerRegistry]

static pluginPath() → str

Returns the path to the application plugin directory.

Return type:

str

static pointCloudRendererRegistry() → QgsPointCloudRendererRegistry | None

Returns the application’s point cloud renderer registry, used for managing point cloud layer 2D renderers.

Added in version 3.18.

Return type:

Optional[QgsPointCloudRendererRegistry]

static prefixPath() → str

Returns the path to the application prefix directory.

Return type:

str

static processingRegistry() → QgsProcessingRegistry | None

Returns the application’s processing registry, used for managing processing providers, algorithms, and various parameters and outputs.

Return type:

Optional[QgsProcessingRegistry]

static profileSourceRegistry() → QgsProfileSourceRegistry | None

Returns registry of available profile source implementations.

Added in version 3.38.

Return type:

Optional[QgsProfileSourceRegistry]

static profiler() → QgsRuntimeProfiler | None

Returns the application runtime profiler.

Return type:

Optional[QgsRuntimeProfiler]

static projectStorageRegistry() → QgsProjectStorageRegistry | None

Returns registry of available project storage implementations.

Added in version 3.2.

Return type:

Optional[QgsProjectStorageRegistry]

static qgisAuthDatabaseFilePath() → str

Returns the path to the user authentication database file: qgis-auth.db.

Deprecated since version 3.30: Use qgisAuthDatabaseUri() instead.

Return type:

str

static qgisAuthDatabaseUri() → str

Returns the URI to the user authentication database. The URI is be in the format: verbatim<DRIVER>://<USER>:<PASSWORD>@<HOST>:<PORT>/<DATABASE>[?OPTIONS]endverbatim where DATABASE is just the path to the file for SQLite databases. If DRIVER is omitted, PSQLITE is assumed. Optional SCHEMA can be specified as a query parameter.

Added in version 3.40.

Return type:

str

static qgisMasterDatabaseFilePath() → str

Returns the path to the master qgis.db file.

Return type:

str

static qgisSettingsDirPath() → str

Returns the path to the settings directory in user’s home dir

Return type:

str

static qgisUserDatabaseFilePath() → str

Returns the path to the user qgis.db file.

Return type:

str

static qmlImportPath() → str

Returns the path where QML components are installed for QGIS Quick library. Returns empty string when QGIS is built without Quick support

Added in version 3.2.

Return type:

str

static recentStyleHandler() → QgsRecentStyleHandler | None

Returns the handler for recently used style items.

Added in version 3.22.

Return type:

Optional[QgsRecentStyleHandler]

static registerGdalDriversFromSettings()

Register gdal drivers, excluding the ones mentioned in “gdal/skipList” setting.

Added in version 3.10.

static registerOgrDrivers()

Register OGR drivers ensuring this only happens once. This is a workaround for an issue with older gdal versions that caused duplicate driver name entries to appear in the list of registered drivers when QgsApplication.registerOgrDrivers was called multiple times.

static relativePathToAbsolutePath(rpath: str | None, targetPath: str | None) → str

Converts path relative to target to an absolute path

Parameters:

• rpath (Optional[str])

• targetPath (Optional[str])

Return type:

str

static renderer3DRegistry() → Qgs3DRendererRegistry | None

Returns registry of available 3D renderers.

Return type:

Optional[Qgs3DRendererRegistry]

static rendererRegistry() → QgsRendererRegistry | None

Returns the application’s renderer registry, used for managing vector layer renderers.

Return type:

Optional[QgsRendererRegistry]

static reportStyleSheet(styleSheetType: QgsApplication.StyleSheetType = QgsApplication.StyleSheetType.Qt) → str

Returns a css style sheet for reports, the styleSheetType argument determines what type of stylesheet is supported by the widget.

Typically you will use this method by calling:

report_style = QgsApplication.reportStyleSheet()
text_browser_report.document().setDefaultStyleSheet(report_style)

if you are using a QgsWebView you will need to manually inject the CSS into a head -> script tag instead.

Return type:

str

Returns:

the stylesheet CSS rules.

Note

if styleSheetType equals StyleSheetType.Qt you can use the special Qt extensions too, for example the gradient fills for backgrounds.

Parameters:

styleSheetType (QgsApplication.StyleSheetType = QgsApplication.StyleSheetType.Qt)

signal requestForTranslatableObjects(translationContext: QgsTranslationContext)

Emitted when project strings which require translation are being collected for inclusion in a .ts file. In order to register translatable strings, connect to this signal and register the strings within the specified translationContext.

Added in version 3.4.

Parameters:

translationContext (QgsTranslationContext)

static resolvePkgPath() → str

Calculate the application pkg path

Return type:

str

Returns:

the resolved pkg path

static restoreGdalDriver(driver: str | None)

Sets the GDAL_SKIP environment variable to exclude the specified driver and then calls GDALDriverManager.AutoSkipDrivers() to unregister it. The driver name should be the short format of the Gdal driver name e.g. GTIFF.

Parameters:

driver (Optional[str])

static scaleBarRendererRegistry() → QgsScaleBarRendererRegistry | None

Gets the registry of available scalebar renderers.

Added in version 3.14.

Return type:

Optional[QgsScaleBarRendererRegistry]

static scaleIconSize(standardSize: int, applyDevicePixelRatio: bool = False) → int

Scales an icon size to compensate for display pixel density, making the icon size hi-dpi friendly, whilst still resulting in pixel-perfect sizes for low-dpi displays.

standardSize should be set to a standard icon size, e.g. 16, 24, 48, etc.

Added in version 3.16.

Parameters:

• standardSize (int)

• applyDevicePixelRatio (bool = False)

Return type:

int

static sensorRegistry() → QgsSensorRegistry | None

Returns the application’s sensor registry, used for sensor types.

Added in version 3.32.

Return type:

Optional[QgsSensorRegistry]

static serverResourcesPath() → str

Returns the path to the server resources directory.

Return type:

str

static setAuthDatabaseDirPath(authDbDirPath: str | None)

Alters authentication data base directory path - used by 3rd party apps

Parameters:

authDbDirPath (Optional[str])

static setCustomVariable(name: str | None, value: Any)

Set a single custom expression variable.

Parameters:

• name (Optional[str])

• value (Any)

static setCustomVariables(customVariables: Dict[str, Any])

Custom expression variables for this application. Do not include generated variables (like system name, user name etc.)

See also

QgsExpressionContextUtils.globalScope()

Parameters:

customVariables (Dict[str, Any])

static setDefaultSvgPaths(pathList: Iterable[str | None])

Alters default svg paths - used by 3rd party apps.

Parameters:

pathList (Iterable[Optional[str]])

static setFileOpenEventReceiver(receiver: QObject | None)

Sets the FileOpen event receiver

Parameters:

receiver (Optional[QObject])

static setLocale(locale: QLocale)

Sets the QGIS locale - used mainly by 3rd party apps and tests. In QGIS this is internally triggered by the application in startup.

Added in version 3.22.2.

Parameters:

locale (QLocale)

static setMaxThreads(maxThreads: int)

Set maximum concurrent thread count

Note

must be between 2 and #cores, -1 means use all available cores

Parameters:

maxThreads (int)

static setNullRepresentation(nullRepresentation: str | None)

Sets the string used to represent the value NULL throughout QGIS.

Note

In general, when passing values around, prefer to use an invalid QVariant. The nullRepresentation() value should only be used in the final presentation step when showing values in a widget or sending it to a web browser.

See also

nullRepresentation()

See also

nullRepresentationChanged()

Parameters:

nullRepresentation (Optional[str])

static setPkgDataPath(pkgDataPath: str | None)

Alters pkg data path - used by 3rd party apps

Parameters:

pkgDataPath (Optional[str])

static setPluginPath(pluginPath: str | None)

Alters plugin path - used by 3rd party apps

Parameters:

pluginPath (Optional[str])

static setPrefixPath(prefixPath: str | None, useDefaultPaths: bool = False)

Alters prefix path - used by 3rd party apps

Parameters:

• prefixPath (Optional[str])

• useDefaultPaths (bool = False)

static setSkippedGdalDrivers(skippedGdalDrivers: Iterable[str | None], deferredSkippedGdalDrivers: Iterable[str | None])

Sets the list of gdal drivers that should be disabled (skippedGdalDrivers), but excludes for now the ones defines in deferredSkippedGdalDrivers. This writes the “gdal/skipList” setting.

Added in version 3.10.

Parameters:

• skippedGdalDrivers (Iterable[Optional[str]])

• deferredSkippedGdalDrivers (Iterable[Optional[str]])

static setSvgPaths(svgPaths: Iterable[str | None])

Sets the paths to svg directories and invalidates the svg path list cache.

Added in version 3.18.

Parameters:

svgPaths (Iterable[Optional[str]])

static setThemeName(themeName: str | None)

Set the active theme to the specified theme. The theme name should be a single word e.g. ‘default’,’classic’. The theme search path usually will be pkgDataPath + “/themes/” + themName + “/” but plugin writers etc can use themeName() as a basis for searching for resources in their own datastores e.g. a Qt4 resource bundle.

Note

A basic test will be carried out to ensure the theme search path based on the supplied theme name exists. If it does not the theme name will be reverted to ‘default’.

Parameters:

themeName (Optional[str])

static setTranslation(translation: str | None)

Set translation locale code

Added in version 3.4.

Parameters:

translation (Optional[str])

static setUITheme(themeName: str | None)

Set the current UI theme used to style the interface. Use uiThemes() to find valid themes to use. Variables found in variables.qss will be added to the stylesheet on load.

Parameters:

themeName (Optional[str]) – The name of the theme.

Note

using an invalid theme name will reset to default

static settingsRegistryCore() → QgsSettingsRegistryCore | None

Returns the application’s settings registry, used for managing application settings.

Added in version 3.20.

Deprecated since version 3.30: Use QgsSettings.treeRoot() instead.

Return type:

Optional[QgsSettingsRegistryCore]

static shortNameRegularExpression() → QRegularExpression

Returns the short name regular expression for line edit validator

Note

This functionality was previously available as shortNameRegExp for QGIS <= 3.20

Added in version 3.22.

Return type:

QRegularExpression

static showSettings() → str

Convenience function to get a summary of the paths used in this application instance useful for debugging mainly.

Return type:

str

static skipGdalDriver(driver: str | None)

Sets the GDAL_SKIP environment variable to include the specified driver and then calls GDALDriverManager.AutoSkipDrivers() to unregister it. The driver name should be the short format of the Gdal driver name e.g. GTIFF.

Parameters:

driver (Optional[str])

static skippedGdalDrivers() → List[str]

Returns the list of gdal drivers that should be skipped (based on GDAL_SKIP environment variable)

Return type:

List[str]

static sourceCache() → QgsSourceCache | None

Returns the application’s source cache, used for caching embedded and remote source strings as local files

Added in version 3.16.

Return type:

Optional[QgsSourceCache]

static splashPath() → str

Returns the path to the splash screen image directory.

Return type:

str

static sponsorsFilePath() → str

Returns the path to the sponsors file.

Return type:

str

static srsDatabaseFilePath() → str

Returns the path to the srs.db file.

Return type:

str

static svgCache() → QgsSvgCache | None

Returns the application’s SVG cache, used for caching SVG images and handling parameter replacement within SVG files.

See also

imageCache()

Return type:

Optional[QgsSvgCache]

static svgPaths() → List[str]

Returns the paths to svg directories.

Return type:

List[str]

static symbol3DRegistry() → Qgs3DSymbolRegistry | None

Returns registry of available 3D symbols.

Added in version 3.16.

Return type:

Optional[Qgs3DSymbolRegistry]

static symbolLayerRegistry() → QgsSymbolLayerRegistry | None

Returns the application’s symbol layer registry, used for managing symbol layers.

Return type:

Optional[QgsSymbolLayerRegistry]

static systemEnvVars() → Dict[str, str]

Returns the system environment variables passed to application.

Return type:

Dict[str, str]

static systemMemorySizeMb() → int

Returns the size of the system memory (RAM) in megabytes.

This is only supported on some platforms, and will return -1 if not supported.

Added in version 3.26.

Return type:

int

static taskManager() → QgsTaskManager | None

Returns the application’s task manager, used for managing application wide background task handling.

Return type:

Optional[QgsTaskManager]

static themeName() → str

Set the active theme to the specified theme. The theme name should be a single word e.g. ‘default’,’classic’. The theme search path usually will be pkgDataPath + “/themes/” + themName + “/” but plugin writers etc can use this method as a basis for searching for resources in their own datastores e.g. a Qt4 resource bundle.

Return type:

str

static tiledSceneRendererRegistry() → QgsTiledSceneRendererRegistry | None

Returns the application’s tiled scene renderer registry, used for managing tiled scene layer 2D renderers.

Added in version 3.34.

Return type:

Optional[QgsTiledSceneRendererRegistry]

translation(self) → str

Returns the current application translation locale code

See also

setTranslation()

Added in version 3.22.

Return type:

str

static translatorsFilePath() → str

Returns the path to the sponsors file.

Return type:

str

static uiThemes() → Dict[str, str]

All themes found in ~/.qgis3/themes folder. The path is to the root folder for the theme

Return type:

Dict[str, str]

Returns:

A hash of theme name and theme path. Valid theme folders contain style.qss

Note

Valid theme folders must contain a style.qss file.

static userFullName() → str

Returns the user’s operating system login account full display name.

See also

userLoginName()

Return type:

str

static userLoginName() → str

Returns the user’s operating system login account name.

See also

userFullName()

Return type:

str

static userStylePath() → str

Returns the path to user’s style.

Return type:

str

static userThemesFolder() → str

Returns the path to user’s themes folder

Return type:

str

static validityCheckRegistry() → QgsValidityCheckRegistry | None

Returns the application’s validity check registry, used for managing validity checks.

Added in version 3.6.

Return type:

Optional[QgsValidityCheckRegistry]