Class: QgsVectorLayerFeatureCounter¶

class qgis.core.QgsVectorLayerFeatureCounter(layer: QgsVectorLayer, context: QgsExpressionContext = QgsExpressionContext(), storeSymbolFids: bool = False)¶

Bases: QgsTask

Create a new feature counter for layer.

Parameters

layer (QgsVectorLayer) – Target QgsVectorLayer to perform counting on.
context (QgsExpressionContext = QgsExpressionContext()) – Specific QgsExpressionContext to use during the rendering step.
storeSymbolFids (bool = False) – If True will store the feature ids (fids), otherwise will only count the number of features per symbol. Default False.

Counts the features in a QgsVectorLayer in task. You should most likely not use this directly and instead call QgsVectorLayer.countSymbolFeatures() and connect to the signal QgsVectorLayer.symbolFeatureCountMapChanged().

Methods

`childEvent`
`connectNotify`
`customEvent`
`disconnectNotify`
`featureCount`	Returns the feature count for a particular `legendKey`.
`featureIds`	Returns the feature Ids for a particular `legendKey`.
`finished`	If the task is managed by a `QgsTaskManager`, this will be called after the task has finished (whether through successful completion or via early termination).
`isCanceled`	Will return `True` if task should terminate ASAP.
`isSignalConnected`
`receivers`
`run`	Calculates the feature count and Ids per symbol
`sender`
`senderSignalIndex`
`setProgress`	Sets the task’s current progress.
`timerEvent`

Signals

symbolsCounted

Emitted when the symbols have been counted.

childEvent(self, QChildEvent)¶

connectNotify(self, QMetaMethod)¶

customEvent(self, QEvent)¶

disconnectNotify(self, QMetaMethod)¶

featureCount(self, legendKey: str) → int¶

Returns the feature count for a particular legendKey. If the key has not been found, -1 will be returned.

Parameters: legendKey (str) –
Return type: int

featureIds(self, symbolkey: str) → object¶

Returns the feature Ids for a particular legendKey. If the key has not been found an empty QSet will be returned.

New in version 3.10.

Parameters: symbolkey (str) –
Return type: object

finished(self, result: bool)¶: If the task is managed by a QgsTaskManager, this will be called after the task has finished (whether through successful completion or via early termination). The result argument reflects whether the task was successfully completed or not. This method is always called from the main thread, so it is safe to create widgets and perform other operations which require the main thread. However, the GUI will be blocked for the duration of this method so tasks should avoid performing any lengthy operations here.

isCanceled(self) → bool¶: Will return True if task should terminate ASAP. If the task reports the CanCancel flag, then derived classes’ run() methods should periodically check this and terminate in a safe manner.

isSignalConnected(self, QMetaMethod) → bool¶

receivers(self, PYQT_SIGNAL) → int¶

run(self) → bool¶

Calculates the feature count and Ids per symbol

Return type: bool

sender(self) → QObject¶

senderSignalIndex(self) → int¶

setProgress(self, progress: float)¶

Sets the task’s current progress. The derived class should call this method whenever the task wants to update its progress. Calling will automatically emit the progressChanged signal.

Parameters: progress – percent of progress, from 0.0 - 100.0

symbolsCounted¶: Emitted when the symbols have been counted. [signal]

timerEvent(self, QTimerEvent)¶