The QgsVectorLayerLabelProvider class implements a label provider for vector layers. More...

#include <qgsvectorlayerlabelprovider.h>

Inheritance diagram for QgsVectorLayerLabelProvider:

Public Member Functions
	QgsVectorLayerLabelProvider (QgsVectorLayer layer, bool withFeatureLoop=true, const QgsPalLayerSettings settings=0, const QString &layerName=QString())
	Convenience constructor to initialize the provider from given vector layer. More...

	QgsVectorLayerLabelProvider (const QgsPalLayerSettings &settings, const QString &layerId, const QgsFields &fields, const QgsCoordinateReferenceSystem &crs, QgsAbstractFeatureSource *source, bool ownsSource)
	Construct diagram provider with all the necessary configuration parameters. More...

	~QgsVectorLayerLabelProvider ()

virtual void	drawLabel (QgsRenderContext &context, pal::LabelPosition *label) const override
	draw this label at the position determined by the labeling engine More...

virtual QList< QgsLabelFeature * >	labelFeatures (QgsRenderContext &context) override
	Return list of label features (they are owned by the provider and thus deleted on its destruction) More...

virtual bool	prepare (const QgsRenderContext &context, QStringList &attributeNames)
	Prepare for registration of features. More...

virtual void	registerFeature (QgsFeature &feature, QgsRenderContext &context)
	Register a feature for labeling as one or more QgsLabelFeature objects stored into mLabels. More...

Public Member Functions inherited from QgsAbstractLabelProvider
	QgsAbstractLabelProvider ()
	Construct the provider with default values. More...

virtual	~QgsAbstractLabelProvider ()
	Vritual destructor. More...

Flags	flags () const
	Flags associated with the provider. More...

unsigned int	linePlacementFlags () const
	For layers with linestring geometries - extra placement flags (or-ed combination of QgsPalLayerSettings::LinePlacementFlags) More...

QString	name () const
	Name of the layer (for statistics, debugging etc.) - does not need to be unique. More...

QgsPalLayerSettings::ObstacleType	obstacleType () const
	How the feature geometries will work as obstacles. More...

QgsPalLayerSettings::Placement	placement () const
	What placement strategy to use for the labels. More...

double	priority () const
	Default priority of labels (may be overridden by individual labels) More...

void	setEngine (const QgsLabelingEngineV2 *engine)
	Associate provider with a labeling engine (should be only called internally from QgsLabelingEngineV2) More...

virtual QList< QgsAbstractLabelProvider * >	subProviders ()
	Return list of child providers - useful if the provider needs to put labels into more layers with different configuration. More...

QgsPalLayerSettings::UpsideDownLabels	upsidedownLabels () const
	How to handle labels that would be upside down. More...

Protected Member Functions
void	drawLabelPrivate (pal::LabelPosition *label, QgsRenderContext &context, QgsPalLayerSettings &tmpLyr, QgsPalLabeling::DrawLabelType drawType, double dpiRatio=1.0) const
	Internal label drawing method. More...

void	init ()
	initialization method - called from constructors More...

Protected Attributes
QgsCoordinateReferenceSystem	mCrs
	Layer's CRS. More...

QgsFields	mFields
	Layer's fields. More...

QList< QgsLabelFeature * >	mLabels
	List of generated. More...

QString	mLayerId
	Layer's ID. More...

bool	mOwnsSource
	Whether layer's feature source is owned. More...

QgsPalLayerSettings	mSettings
	Layer's labeling configuration. More...

QgsAbstractFeatureSource *	mSource
	Layer's feature source. More...

Protected Attributes inherited from QgsAbstractLabelProvider
const QgsLabelingEngineV2 *	mEngine
	Associated labeling engine. More...

Flags	mFlags
	Flags altering drawing and registration of features. More...

unsigned int	mLinePlacementFlags
	Extra placement flags for linestring geometries. More...

QString	mName
	Name of the layer. More...

QgsPalLayerSettings::ObstacleType	mObstacleType
	Type of the obstacle of feature geometries. More...

QgsPalLayerSettings::Placement	mPlacement
	Placement strategy. More...

double	mPriority
	Default priority of labels. More...

QgsPalLayerSettings::UpsideDownLabels	mUpsidedownLabels
	How to handle labels that would be upside down. More...

Additional Inherited Members
Public Types inherited from QgsAbstractLabelProvider
enum	Flag { DrawLabels = 1 << 1, DrawAllLabels = 1 << 2, MergeConnectedLines = 1 << 3, CentroidMustBeInside = 1 << 4, FitInPolygonOnly = 1 << 5, LabelPerFeaturePart = 1 << 6 }

Detailed Description

The QgsVectorLayerLabelProvider class implements a label provider for vector layers.

Parameters for the labeling are taken from the layer's custom properties or from the given settings.

Note: added in QGIS 2.12

Definition at line 30 of file qgsvectorlayerlabelprovider.h.

Constructor & Destructor Documentation

QgsVectorLayerLabelProvider::QgsVectorLayerLabelProvider	(	QgsVectorLayer *	layer,
		bool	withFeatureLoop = `true`,
		const QgsPalLayerSettings *	settings = `0`,
		const QString &	layerName = `QString()`
	)

explicit

Convenience constructor to initialize the provider from given vector layer.

Definition at line 47 of file qgsvectorlayerlabelprovider.cpp.

QgsVectorLayerLabelProvider::QgsVectorLayerLabelProvider	(	const QgsPalLayerSettings &	settings,
		const QString &	layerId,
		const QgsFields &	fields,
		const QgsCoordinateReferenceSystem &	crs,
		QgsAbstractFeatureSource *	source,
		bool	ownsSource
	)

Construct diagram provider with all the necessary configuration parameters.

Definition at line 68 of file qgsvectorlayerlabelprovider.cpp.

QgsVectorLayerLabelProvider::~QgsVectorLayerLabelProvider ( )

Definition at line 103 of file qgsvectorlayerlabelprovider.cpp.

Member Function Documentation

void QgsVectorLayerLabelProvider::drawLabel	(	QgsRenderContext &	context,
		pal::LabelPosition *	label
	)		const

overridevirtual

draw this label at the position determined by the labeling engine

Implements QgsAbstractLabelProvider.

Reimplemented in QgsDxfLabelProvider.

Definition at line 282 of file qgsvectorlayerlabelprovider.cpp.

void QgsVectorLayerLabelProvider::drawLabelPrivate	(	pal::LabelPosition *	label,
		QgsRenderContext &	context,
		QgsPalLayerSettings &	tmpLyr,
		QgsPalLabeling::DrawLabelType	drawType,
		double	dpiRatio = `1.0`
	)		const

protected

Internal label drawing method.

Definition at line 380 of file qgsvectorlayerlabelprovider.cpp.

void QgsVectorLayerLabelProvider::init ( )

protected

initialization method - called from constructors

Definition at line 86 of file qgsvectorlayerlabelprovider.cpp.

QList< QgsLabelFeature * > QgsVectorLayerLabelProvider::labelFeatures ( QgsRenderContext & context )

overridevirtual

Return list of label features (they are owned by the provider and thus deleted on its destruction)

Implements QgsAbstractLabelProvider.

Definition at line 240 of file qgsvectorlayerlabelprovider.cpp.

bool QgsVectorLayerLabelProvider::prepare	(	const QgsRenderContext &	context,
		QStringList &	attributeNames
	)

virtual

Prepare for registration of features.

Must be called after provider has been added to engine (uses its map settings)

Parameters

context	render context.
attributeNames	list of attribute names to which additional required attributes shall be added

Returns: Whether the preparation was successful - if not, the provider shall not be used

Reimplemented in QgsRuleBasedLabelProvider.

Definition at line 112 of file qgsvectorlayerlabelprovider.cpp.

void QgsVectorLayerLabelProvider::registerFeature	(	QgsFeature &	feature,
		QgsRenderContext &	context
	)

virtual

Register a feature for labeling as one or more QgsLabelFeature objects stored into mLabels.

Parameters

feature	feature to label
context	render context. The QgsExpressionContext contained within the render context must have already had the feature and fields sets prior to calling this method.

Reimplemented in QgsRuleBasedLabelProvider.

Definition at line 272 of file qgsvectorlayerlabelprovider.cpp.