The QgsAbstractLabelProvider class is an interface class. More...

#include <qgslabelingenginev2.h>

Inheritance diagram for QgsAbstractLabelProvider:

[legend]

Public Types
enum	Flag { DrawLabels = 1 << 1, DrawAllLabels = 1 << 2, MergeConnectedLines = 1 << 3, CentroidMustBeInside = 1 << 4, LabelPerFeaturePart = 1 << 6 }

Public Member Functions
	QgsAbstractLabelProvider (const QString &layerId=QString(), const QString &providerId=QString())
	Construct the provider with default values. More...

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

virtual void	drawLabel (QgsRenderContext &context, pal::LabelPosition *label) const =0
	draw this label at the position determined by the labeling engine More...

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

virtual QList< QgsLabelFeature * >	labelFeatures (QgsRenderContext &context)=0
	Return list of label features (they are owned by the provider and thus deleted on its destruction) More...

QString	layerId () const
	Returns ID of associated layer, or empty string if no layer is 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...

QString	providerId () const
	Returns provider ID - useful in case there is more than one label provider within a layer (e.g. 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 Attributes
const QgsLabelingEngineV2 *	mEngine
	Associated labeling engine. More...

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

QString	mLayerId
	Associated layer's ID, if applicable. 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...

QString	mProviderId
	Associated provider ID (one layer may have multiple providers, e.g. in rule-based labeling) More...

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

Detailed Description

The QgsAbstractLabelProvider class is an interface class.

Implementations return list of labels and their associated geometries - these are used by QgsLabelingEngineV2 to compute the final layout of labels.

Implementations also take care of drawing the returned final label positions.

Note: this class is not a part of public API yet. See notes in QgsLabelingEngineV2; not available in Python bindings; added in QGIS 2.12

Definition at line 42 of file qgslabelingenginev2.h.

Member Enumeration Documentation

◆ Flag

enum QgsAbstractLabelProvider::Flag

Enumerator
DrawLabels	whether the labels should be rendered
DrawAllLabels	whether all features will be labelled even though overlaps occur
MergeConnectedLines	whether adjacent lines (with the same label text) should be merged
CentroidMustBeInside	whether location of centroid must be inside of polygons
LabelPerFeaturePart	whether to label each part of multi-part features separately

Definition at line 54 of file qgslabelingenginev2.h.

Constructor & Destructor Documentation

◆ QgsAbstractLabelProvider()

QgsAbstractLabelProvider::QgsAbstractLabelProvider	(	const QString &	layerId = `QString()`,
		const QString &	providerId = `QString()`
	)

Construct the provider with default values.

Definition at line 384 of file qgslabelingenginev2.cpp.

◆ ~QgsAbstractLabelProvider()

virtual QgsAbstractLabelProvider::~QgsAbstractLabelProvider ( )

inlinevirtual

Vritual destructor.

Definition at line 49 of file qgslabelingenginev2.h.

Member Function Documentation

◆ drawLabel()

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

pure virtual

draw this label at the position determined by the labeling engine

Implemented in QgsDxfRuleBasedLabelProvider, QgsVectorLayerDiagramProvider, QgsVectorLayerLabelProvider, and QgsDxfLabelProvider.

◆ flags()

Flags QgsAbstractLabelProvider::flags ( ) const

inline

Flags associated with the provider.

Definition at line 85 of file qgslabelingenginev2.h.

◆ labelFeatures()

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

pure virtual

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

Implemented in QgsVectorLayerDiagramProvider, and QgsVectorLayerLabelProvider.

◆ layerId()

QString QgsAbstractLabelProvider::layerId ( ) const

inline

Returns ID of associated layer, or empty string if no layer is associated with the provider.

Definition at line 77 of file qgslabelingenginev2.h.

◆ linePlacementFlags()

unsigned int QgsAbstractLabelProvider::linePlacementFlags ( ) const

inline

For layers with linestring geometries - extra placement flags (or-ed combination of QgsPalLayerSettings::LinePlacementFlags)

Definition at line 91 of file qgslabelingenginev2.h.

◆ name()

QString QgsAbstractLabelProvider::name ( ) const

inline

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

Definition at line 74 of file qgslabelingenginev2.h.

◆ obstacleType()

QgsPalLayerSettings::ObstacleType QgsAbstractLabelProvider::obstacleType ( ) const

inline

How the feature geometries will work as obstacles.

Definition at line 97 of file qgslabelingenginev2.h.

◆ placement()

QgsPalLayerSettings::Placement QgsAbstractLabelProvider::placement ( ) const

inline

What placement strategy to use for the labels.

Definition at line 88 of file qgslabelingenginev2.h.

◆ priority()

double QgsAbstractLabelProvider::priority ( ) const

inline

Default priority of labels (may be overridden by individual labels)

Definition at line 94 of file qgslabelingenginev2.h.

◆ providerId()

QString QgsAbstractLabelProvider::providerId ( ) const

inline

Returns provider ID - useful in case there is more than one label provider within a layer (e.g.

in case of rule-based labeling - provider ID = rule's key). May be empty string if layer ID is sufficient for identification of provider's configuration.

Definition at line 82 of file qgslabelingenginev2.h.

◆ setEngine()

void QgsAbstractLabelProvider::setEngine ( const QgsLabelingEngineV2 * engine )

inline

Associate provider with a labeling engine (should be only called internally from QgsLabelingEngineV2)

Definition at line 52 of file qgslabelingenginev2.h.

◆ subProviders()

virtual QList<QgsAbstractLabelProvider*> QgsAbstractLabelProvider::subProviders ( )

inlinevirtual

Return list of child providers - useful if the provider needs to put labels into more layers with different configuration.

Reimplemented in QgsRuleBasedLabelProvider.

Definition at line 71 of file qgslabelingenginev2.h.

◆ upsidedownLabels()

QgsPalLayerSettings::UpsideDownLabels QgsAbstractLabelProvider::upsidedownLabels ( ) const

inline

How to handle labels that would be upside down.

Definition at line 100 of file qgslabelingenginev2.h.

Member Data Documentation

◆ mEngine

const QgsLabelingEngineV2* QgsAbstractLabelProvider::mEngine

protected

Associated labeling engine.

Definition at line 104 of file qgslabelingenginev2.h.

◆ mFlags

Flags QgsAbstractLabelProvider::mFlags

protected

Flags altering drawing and registration of features.

Definition at line 113 of file qgslabelingenginev2.h.

◆ mLayerId

QString QgsAbstractLabelProvider::mLayerId

protected

Associated layer's ID, if applicable.

Definition at line 109 of file qgslabelingenginev2.h.

◆ mLinePlacementFlags

unsigned int QgsAbstractLabelProvider::mLinePlacementFlags

protected

Extra placement flags for linestring geometries.

Definition at line 117 of file qgslabelingenginev2.h.

◆ mName

QString QgsAbstractLabelProvider::mName

protected

Name of the layer.

Definition at line 107 of file qgslabelingenginev2.h.

◆ mObstacleType

QgsPalLayerSettings::ObstacleType QgsAbstractLabelProvider::mObstacleType

protected

Type of the obstacle of feature geometries.

Definition at line 121 of file qgslabelingenginev2.h.

◆ mPlacement

QgsPalLayerSettings::Placement QgsAbstractLabelProvider::mPlacement

protected

Placement strategy.

Definition at line 115 of file qgslabelingenginev2.h.

◆ mPriority

double QgsAbstractLabelProvider::mPriority

protected

Default priority of labels.

Definition at line 119 of file qgslabelingenginev2.h.

◆ mProviderId

QString QgsAbstractLabelProvider::mProviderId

protected

Associated provider ID (one layer may have multiple providers, e.g. in rule-based labeling)

Definition at line 111 of file qgslabelingenginev2.h.

◆ mUpsidedownLabels

QgsPalLayerSettings::UpsideDownLabels QgsAbstractLabelProvider::mUpsidedownLabels

protected

How to handle labels that would be upside down.

Definition at line 123 of file qgslabelingenginev2.h.

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

/tmp/buildd/qgis-2.18.21+99unstable/src/core/qgslabelingenginev2.h
/tmp/buildd/qgis-2.18.21+99unstable/src/core/qgslabelingenginev2.cpp

Public Types

Public Member Functions

Protected Attributes

Detailed Description

Member Enumeration Documentation

◆ Flag

Constructor & Destructor Documentation

◆ QgsAbstractLabelProvider()

◆ ~QgsAbstractLabelProvider()

Member Function Documentation

◆ drawLabel()

◆ flags()

◆ labelFeatures()

◆ layerId()

◆ linePlacementFlags()

◆ name()

◆ obstacleType()

◆ placement()

◆ priority()

◆ providerId()

◆ setEngine()

◆ subProviders()

◆ upsidedownLabels()

Member Data Documentation

◆ mEngine

◆ mFlags

◆ mLayerId

◆ mLinePlacementFlags

◆ mName

◆ mObstacleType

◆ mPlacement

◆ mPriority

◆ mProviderId

◆ mUpsidedownLabels