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

#include <qgsvectorlayerfeaturecounter.h>

Inheritance diagram for QgsVectorLayerFeatureCounter:

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

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

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

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

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

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). More...

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

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

bool	run () override
	Performs the task's operation. More...

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

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

	~QgsTask () override

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

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

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

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

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

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

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

void	hold ()
	Places the task on hold. More...

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

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

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

TaskStatus	status () const
	Returns the current task status. More...

void	unhold ()
	Releases the task from being held. More...

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

Additional Inherited Members
Public Types inherited from QgsTask
enum	Flag { CanCancel = 1 << 1, AllFlags = CanCancel }
	Task flags. More...

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. More...

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). More...

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

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().

Since: QGIS 3.0

Definition at line 32 of file qgsvectorlayerfeaturecounter.h.

Constructor & Destructor Documentation

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

Create a new feature counter for layer.

Definition at line 19 of file qgsvectorlayerfeaturecounter.cpp.

Member Function Documentation

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

Gets the feature count for a particular legendKey.

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

Definition at line 102 of file qgsvectorlayerfeaturecounter.cpp.

bool QgsVectorLayerFeatureCounter::run ( )

overridevirtual

Performs the task's operation.

This method will be called when the task commences (ie via calling start() ), and subclasses should implement the operation they wish to perform in the background within this method.

A task must return a boolean value to indicate whether the task was completed successfully or terminated before completion.

Implements QgsTask.

Definition at line 32 of file qgsvectorlayerfeaturecounter.cpp.

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

Gets the count for each symbol.

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