Counts the features in a QgsVectorLayer in task. More...

#include <qgsvectorlayerfeaturecounter.h>

Inheritance diagram for QgsVectorLayerFeatureCounter:

[legend]

Signals
void	symbolsCounted ()
	Emitted when the symbols have been counted.

Signals inherited from QgsTask
void	begun ()
	Will be emitted by task to indicate its commencement.

void	progressChanged (double progress)
	Will be emitted by task when its progress changes.

void	statusChanged (int status)
	Will be emitted by task when its status changes.

void	taskCompleted ()
	Will be emitted by task to indicate its successful completion.

void	taskTerminated ()
	Will be emitted by task if it has terminated for any reason other then completion (e.g., when a task has been canceled or encountered an internal error).

Public Member Functions
	QgsVectorLayerFeatureCounter (QgsVectorLayer *layer, const QgsExpressionContext &context=QgsExpressionContext(), bool storeSymbolFids=false)
	Create a new feature counter for layer.

	~QgsVectorLayerFeatureCounter () override

void	cancel () override
	Notifies the task that it should terminate.

long long	featureCount (const QString &legendKey) const
	Returns the feature count for a particular legendKey.

QgsFeatureIds	featureIds (const QString &symbolkey) const
	Returns the feature Ids for a particular legendKey.

bool	run () override
	Calculates the feature count and Ids per symbol.

QHash< QString, long long >	symbolFeatureCountMap () const
	Returns the count for each symbol.

QHash< QString, QgsFeatureIds >	symbolFeatureIdMap () const
	Returns the QgsFeatureIds for each symbol.

Public Member Functions inherited from QgsTask
	QgsTask (const QString &description=QString(), QgsTask::Flags flags=AllFlags)
	Constructor for QgsTask.

	~QgsTask () override

void	addSubTask (QgsTask *subTask, const QgsTaskList &dependencies=QgsTaskList(), SubTaskDependency subTaskDependency=SubTaskIndependent)
	Adds a subtask to this task.

bool	canCancel () const
	Returns `true` if the task can be canceled.

QList< QgsMapLayer * >	dependentLayers () const
	Returns the list of layers on which the task depends.

QString	description () const
	Returns the task's description.

qint64	elapsedTime () const
	Returns the elapsed time since the task commenced, in milliseconds.

Flags	flags () const
	Returns the flags associated with the task.

void	hold ()
	Places the task on hold.

bool	isActive () const
	Returns `true` if the task is active, ie it is not complete and has not been canceled.

double	progress () const
	Returns the task's progress (between 0.0 and 100.0)

void	setDependentLayers (const QList< QgsMapLayer * > &dependentLayers)
	Sets a list of layers on which the task depends.

void	setDescription (const QString &description)
	Sets the task's description.

TaskStatus	status () const
	Returns the current task status.

void	unhold ()
	Releases the task from being held.

bool	waitForFinished (int timeout=30000)
	Blocks the current thread until the task finishes or a maximum of timeout milliseconds.

Additional Inherited Members
Public Types inherited from QgsTask
enum	Flag { CanCancel = 1 << 1 , CancelWithoutPrompt = 1 << 2 , Hidden = 1 << 3 , Silent = 1 << 4 , AllFlags = CanCancel }
	Task flags. More...

typedef QFlags< Flag >	Flags

enum	SubTaskDependency { SubTaskIndependent = 0 , ParentDependsOnSubTask }
	Controls how subtasks relate to their parent task. More...

enum	TaskStatus { Queued , OnHold , Running , Complete , Terminated }
	Status of tasks. More...

Protected Slots inherited from QgsTask
void	setProgress (double progress)
	Sets the task's current progress.

Protected Member Functions inherited from QgsTask
virtual void	finished (bool result)
	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).

bool	isCanceled () const
	Will return `true` if task should terminate ASAP.

Detailed Description

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().

Definition at line 33 of file qgsvectorlayerfeaturecounter.h.

Constructor & Destructor Documentation

◆ QgsVectorLayerFeatureCounter()

QgsVectorLayerFeatureCounter::QgsVectorLayerFeatureCounter	(	QgsVectorLayer *	layer,
		const QgsExpressionContext &	context = `QgsExpressionContext()`,
		bool	storeSymbolFids = `false`
	)

Create a new feature counter for layer.

Parameters

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

Definition at line 23 of file qgsvectorlayerfeaturecounter.cpp.

◆ ~QgsVectorLayerFeatureCounter()

QgsVectorLayerFeatureCounter::~QgsVectorLayerFeatureCounter ( )

overridedefault

Member Function Documentation

◆ cancel()

void QgsVectorLayerFeatureCounter::cancel ( )

overridevirtual

Notifies the task that it should terminate.

Calling this is not guaranteed to immediately end the task, rather it sets the isCanceled() flag which task subclasses can check and terminate their operations at an appropriate time. Any subtasks owned by this task will also be canceled. Derived classes must ensure that the base class implementation is called from any overridden version.

See also: isCanceled()

Reimplemented from QgsTask.

Definition at line 116 of file qgsvectorlayerfeaturecounter.cpp.

◆ featureCount()

long long QgsVectorLayerFeatureCounter::featureCount ( const QString & legendKey ) const

Returns the feature count for a particular legendKey.

If the key has not been found, -1 will be returned.

Definition at line 128 of file qgsvectorlayerfeaturecounter.cpp.

◆ featureIds()

QgsFeatureIds QgsVectorLayerFeatureCounter::featureIds ( const QString & symbolkey ) const

Returns the feature Ids for a particular legendKey.

If the key has not been found an empty QSet will be returned.

Since: QGIS 3.10

Definition at line 138 of file qgsvectorlayerfeaturecounter.cpp.

◆ run()

bool QgsVectorLayerFeatureCounter::run ( )

overridevirtual

Calculates the feature count and Ids per symbol.

Implements QgsTask.

Definition at line 39 of file qgsvectorlayerfeaturecounter.cpp.

◆ symbolFeatureCountMap()

QHash< QString, long long > QgsVectorLayerFeatureCounter::symbolFeatureCountMap ( ) const

Returns the count for each symbol.

Only valid after the symbolsCounted() signal has been emitted.

Note: Not available in Python bindings.

Definition at line 123 of file qgsvectorlayerfeaturecounter.cpp.

◆ symbolFeatureIdMap()

QHash< QString, QgsFeatureIds > QgsVectorLayerFeatureCounter::symbolFeatureIdMap ( ) const

Returns the QgsFeatureIds for each symbol.

Only valid after the symbolsCounted() signal has been emitted.

See also: symbolFeatureCountMap

Note: Not available in Python bindings.

Since: QGIS 3.10

Definition at line 133 of file qgsvectorlayerfeaturecounter.cpp.

◆ symbolsCounted

void QgsVectorLayerFeatureCounter::symbolsCounted ( )

signal

Emitted when the symbols have been counted.

The documentation for this class was generated from the following files:

/build/qgis-3.41.0+git20241116+25ec5511245+99sid/src/core/vector/qgsvectorlayerfeaturecounter.h
/build/qgis-3.41.0+git20241116+25ec5511245+99sid/src/core/vector/qgsvectorlayerfeaturecounter.cpp

Signals

Public Member Functions

Additional Inherited Members