Base class for labeling engine rules which prevents labels being placed too close or to far from features from a different layer. More...

#include <qgslabelingenginerule_impl.h>

Inheritance diagram for QgsAbstractLabelingEngineRuleDistanceFromFeature:

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Public Member Functions
	QgsAbstractLabelingEngineRuleDistanceFromFeature ()

	~QgsAbstractLabelingEngineRuleDistanceFromFeature () override

void	alterCandidateCost (pal::LabelPosition *candidate, QgsLabelingEngineContext &context) const override
	Provides an opportunity for the rule to alter the cost for a candidate.

bool	candidateIsIllegal (const pal::LabelPosition *candidate, QgsLabelingEngineContext &context) const override
	Returns `true` if a labeling candidate violates the rule and should be eliminated.

double	cost () const
	Returns the penalty cost incurred when the rule is violated.

double	distance () const
	Returns the acceptable distance threshold between labels and the features from the targetLayer().

Qgis::RenderUnit	distanceUnit () const
	Returns the units for the distance between labels and the features from the targetLayer().

const QgsMapUnitScale &	distanceUnitScale () const
	Returns the scaling for the distance between labels and the features from the targetLayer().

bool	isAvailable () const override
	Returns `true` if the rule is available for use within the current QGIS environment.

QgsMapLayer *	labeledLayer () const
	Returns the layer providing the labels.

bool	prepare (QgsRenderContext &context) override
	Prepares the rule.

void	readXml (const QDomElement &element, const QgsReadWriteContext &context) override
	Reads the rule properties from an XML element.

void	resolveReferences (const QgsProject *project) override
	Resolves reference to layers from stored layer ID.

void	setCost (double cost)
	Sets the penalty cost incurred when the rule is violated.

void	setDistance (double distance)
	Sets the acceptable distance threshold between labels and the features from the targetLayer().

void	setDistanceUnit (Qgis::RenderUnit unit)
	Sets the unit for the distance between labels and the features from the targetLayer().

void	setDistanceUnitScale (const QgsMapUnitScale &scale)
	Sets the scale for the distance between labels and the features from the targetLayer().

void	setLabeledLayer (QgsMapLayer *layer)
	Sets the layer providing the labels.

void	setTargetLayer (QgsVectorLayer *layer)
	Sets the layer providing the features which labels must be distant from (or close to).

QgsVectorLayer *	targetLayer () const
	Returns the layer providing the features which labels must be distant from (or close to).

void	writeXml (QDomDocument &doc, QDomElement &element, const QgsReadWriteContext &context) const override
	Writes the rule properties to an XML element.

Public Member Functions inherited from QgsAbstractLabelingEngineRule
virtual	~QgsAbstractLabelingEngineRule ()

bool	active () const
	Returns `true` if the rule is active.

virtual bool	candidatesAreConflicting (const pal::LabelPosition lp1, const pal::LabelPosition lp2) const
	Returns `true` if a labeling candidate lp1 conflicts with lp2 after applying the rule.

virtual QgsAbstractLabelingEngineRule *	clone () const =0
	Creates a clone of this rule.

virtual QString	description () const
	Returns a user-friendly description of the rule.

virtual QString	displayType () const =0
	Returns a user-friendly, translated string representing the rule type.

virtual QString	id () const =0
	Returns a string uniquely identifying the rule subclass.

virtual QgsRectangle	modifyCandidateConflictSearchBoundingBox (const QgsRectangle &candidateBounds) const
	Returns a (possibly expanded) bounding box to use when searching for conflicts for a candidate.

QString	name () const
	Returns the name for this instance of the rule.

void	setActive (bool active)
	Sets whether the rule is active.

void	setName (const QString &name)
	Sets the name for this instance of the rule.

Protected Member Functions
void	copyCommonProperties (QgsAbstractLabelingEngineRule *other) const override
	Copies common properties from this object to an other.

Protected Attributes
bool	mMustBeDistant = true
	`true` if labels must be distant from features, `false` if they must be close

Detailed Description

Base class for labeling engine rules which prevents labels being placed too close or to far from features from a different layer.

Since: QGIS 3.40

Definition at line 34 of file qgslabelingenginerule_impl.h.

Constructor & Destructor Documentation

◆ QgsAbstractLabelingEngineRuleDistanceFromFeature()

QgsAbstractLabelingEngineRuleDistanceFromFeature::QgsAbstractLabelingEngineRuleDistanceFromFeature ( )

default

◆ ~QgsAbstractLabelingEngineRuleDistanceFromFeature()

QgsAbstractLabelingEngineRuleDistanceFromFeature::~QgsAbstractLabelingEngineRuleDistanceFromFeature ( )

overridedefault

Member Function Documentation

◆ alterCandidateCost()

void QgsAbstractLabelingEngineRuleDistanceFromFeature::alterCandidateCost	(	pal::LabelPosition *	candidate,
		QgsLabelingEngineContext &	context
	)		const

overridevirtual

Provides an opportunity for the rule to alter the cost for a candidate.

The default implementation does nothing.

Reimplemented from QgsAbstractLabelingEngineRule.

Definition at line 117 of file qgslabelingenginerule_impl.cpp.

◆ candidateIsIllegal()

bool QgsAbstractLabelingEngineRuleDistanceFromFeature::candidateIsIllegal	(	const pal::LabelPosition *	candidate,
		QgsLabelingEngineContext &	context
	)		const

overridevirtual

Returns true if a labeling candidate violates the rule and should be eliminated.

The default implementation returns false.

Reimplemented from QgsAbstractLabelingEngineRule.

Definition at line 100 of file qgslabelingenginerule_impl.cpp.

◆ copyCommonProperties()

void QgsAbstractLabelingEngineRuleDistanceFromFeature::copyCommonProperties ( QgsAbstractLabelingEngineRule * other ) const

overrideprotectedvirtual

Copies common properties from this object to an other.

Reimplemented from QgsAbstractLabelingEngineRule.

Definition at line 168 of file qgslabelingenginerule_impl.cpp.

◆ cost()

double QgsAbstractLabelingEngineRuleDistanceFromFeature::cost ( ) const

inline

Returns the penalty cost incurred when the rule is violated.

This is a value between 0 and 10, where 10 indicates that the rule must never be violated, and 1-9 = nice to have if possible, where higher numbers will try harder to avoid violating the rule.

See also: setCost()

Definition at line 138 of file qgslabelingenginerule_impl.h.

◆ distance()

double QgsAbstractLabelingEngineRuleDistanceFromFeature::distance ( ) const

inline

Returns the acceptable distance threshold between labels and the features from the targetLayer().

See also: setDistance(); distanceUnit()

Definition at line 83 of file qgslabelingenginerule_impl.h.

◆ distanceUnit()

Qgis::RenderUnit QgsAbstractLabelingEngineRuleDistanceFromFeature::distanceUnit ( ) const

inline

Returns the units for the distance between labels and the features from the targetLayer().

See also: setDistanceUnit(); distance()

Definition at line 101 of file qgslabelingenginerule_impl.h.

◆ distanceUnitScale()

const QgsMapUnitScale & QgsAbstractLabelingEngineRuleDistanceFromFeature::distanceUnitScale ( ) const

inline

Returns the scaling for the distance between labels and the features from the targetLayer().

See also: setDistanceUnitScale(); distance()

Definition at line 119 of file qgslabelingenginerule_impl.h.

◆ isAvailable()

bool QgsAbstractLabelingEngineRuleDistanceFromFeature::isAvailable ( ) const

overridevirtual

Returns true if the rule is available for use within the current QGIS environment.

The base class method returns true.

Rules can return false if required dependencies are not available, e.g. if a library version is too old for the rule.

Reimplemented from QgsAbstractLabelingEngineRule.

Definition at line 139 of file qgslabelingenginerule_impl.cpp.

◆ labeledLayer()

QgsMapLayer * QgsAbstractLabelingEngineRuleDistanceFromFeature::labeledLayer ( ) const

Returns the layer providing the labels.

See also: setLabeledLayer()

Definition at line 148 of file qgslabelingenginerule_impl.cpp.

◆ prepare()

bool QgsAbstractLabelingEngineRuleDistanceFromFeature::prepare ( QgsRenderContext & context )

overridevirtual

Prepares the rule.

This must be called on the main render thread, prior to commencing the render operation. Thread sensitive logic (such as creation of feature sources) can be performed in this method.

Implements QgsAbstractLabelingEngineRule.

Definition at line 36 of file qgslabelingenginerule_impl.cpp.

◆ readXml()

void QgsAbstractLabelingEngineRuleDistanceFromFeature::readXml	(	const QDomElement &	element,
		const QgsReadWriteContext &	context
	)

overridevirtual

Reads the rule properties from an XML element.

See also: resolveReferences(); writeXml()

Implements QgsAbstractLabelingEngineRule.

Definition at line 71 of file qgslabelingenginerule_impl.cpp.

◆ resolveReferences()

void QgsAbstractLabelingEngineRuleDistanceFromFeature::resolveReferences ( const QgsProject * project )

overridevirtual

Resolves reference to layers from stored layer ID.

Should be called following a call readXml().

Reimplemented from QgsAbstractLabelingEngineRule.

Definition at line 94 of file qgslabelingenginerule_impl.cpp.

◆ setCost()

void QgsAbstractLabelingEngineRuleDistanceFromFeature::setCost ( double cost )

inline

Sets the penalty cost incurred when the rule is violated.

This is a value between 0 and 10, where 10 indicates that the rule must never be violated, and 1-9 = nice to have if possible, where higher numbers will try harder to avoid violating the rule.