A child rule for QgsRuleBasedLabeling. More...

#include <qgsrulebasedlabeling.h>

Public Types
enum	RegisterResult { Filtered = 0 , Inactive , Registered }
	The result of registering a rule. More...

Public Member Functions
	Rule (const Rule &rh)=delete

	Rule (QgsPalLayerSettings *settings, double maximumScale=0, double minimumScale=0, const QString &filterExp=QString(), const QString &description=QString(), bool elseRule=false)
	takes ownership of settings, settings may be `nullptr`

	~Rule ()

bool	accept (QgsStyleEntityVisitorInterface *visitor) const
	Accepts the specified symbology visitor, causing it to visit all child rules associated with the rule.

bool	active () const
	Returns if this rule is active.

void	appendChild (QgsRuleBasedLabeling::Rule *rule)
	add child rule, take ownership, sets this as parent

QgsRuleBasedLabeling::RuleList &	children ()
	Returns all children rules of this rule.

const QgsRuleBasedLabeling::RuleList &	children () const
	Returns all children rules of this rule.

QgsRuleBasedLabeling::Rule *	clone (bool resetRuleKey=true) const
	clone this rule

void	createSubProviders (QgsVectorLayer layer, RuleToProviderVec &subProviders, QgsRuleBasedLabelProvider provider)
	add providers

bool	dependsOnScale () const
	Determines if scale based labeling is active.

QgsRuleBasedLabeling::RuleList	descendants () const
	Returns all children, grand-children, grand-grand-children, grand-gra... you get it.

QString	description () const
	A human readable description for this rule.

QString	filterExpression () const
	A filter that will check if this rule applies.

QgsRuleBasedLabeling::Rule *	findRuleByKey (const QString &key)
	Find a labeling rule thanks to its key.

const QgsRuleBasedLabeling::Rule *	findRuleByKey (const QString &key) const
	Try to find a rule given its unique key.

void	insertChild (int i, QgsRuleBasedLabeling::Rule *rule)
	add child rule, take ownership, sets this as parent

bool	isElse () const
	Check if this rule is an ELSE rule.

double	maximumScale () const
	Returns the maximum map scale (i.e.

double	minimumScale () const
	Returns the minimum map scale (i.e.

Rule &	operator= (const Rule &rh)=delete

QgsRuleBasedLabeling::Rule *	parent ()
	The parent rule.

const QgsRuleBasedLabeling::Rule *	parent () const
	The parent rule.

void	prepare (QgsRenderContext &context, QSet< QString > &attributeNames, RuleToProviderVec &subProviders)
	call prepare() on sub-providers and populate attributeNames

std::tuple< RegisterResult, QList< QgsLabelFeature * > >	registerFeature (const QgsFeature &feature, QgsRenderContext &context, RuleToProviderVec &subProviders, const QgsGeometry &obstacleGeometry=QgsGeometry(), const QgsSymbol *symbol=nullptr)
	Register individual features.

void	removeChildAt (int i)
	delete child rule

bool	requiresAdvancedEffects () const
	Returns `true` if this rule or any of its children requires advanced composition effects to render.

QString	ruleKey () const
	Unique rule identifier (for identification of rule within labeling, used as provider ID)

QDomElement	save (QDomDocument &doc, const QgsReadWriteContext &context) const
	store labeling info to XML element

void	setActive (bool state)
	Sets if this rule is active.

void	setDescription (const QString &description)
	Set a human readable description for this rule.

void	setFilterExpression (const QString &filterExp)
	Set the expression used to check if a given feature shall be rendered with this rule.

void	setIsElse (bool iselse)
	Sets if this rule is an ELSE rule.

void	setMaximumScale (double scale)
	Sets the maximum map scale (i.e.

void	setMinimumScale (double scale)
	Sets the minimum map scale (i.e.

void	setRuleKey (const QString &key)
	Override the assigned rule key (should be used just internally by rule-based labeling)

void	setSettings (QgsPalLayerSettings *settings)
	Sets new settings (or `nullptr`). Deletes old settings if any.

QgsPalLayerSettings *	settings () const
	Returns the labeling settings.

void	subProviderIds (QStringList &list) const
	append rule keys of descendants that contain valid settings (i.e.

Static Public Member Functions
static QgsRuleBasedLabeling::Rule *	create (const QDomElement &ruleElem, const QgsReadWriteContext &context, bool reuseId=true)
	Create a rule from an XML definition.

Detailed Description

A child rule for QgsRuleBasedLabeling.

Definition at line 56 of file qgsrulebasedlabeling.h.

Member Enumeration Documentation

◆ RegisterResult

enum QgsRuleBasedLabeling::Rule::RegisterResult

The result of registering a rule.

Enumerator
Filtered	The rule does not apply.
Inactive	The rule is inactive.
Registered	Something was registered.

Definition at line 67 of file qgsrulebasedlabeling.h.

Constructor & Destructor Documentation

◆ Rule() [1/2]

QgsRuleBasedLabeling::Rule::Rule	(	QgsPalLayerSettings *	settings,
		double	maximumScale = `0`,
		double	minimumScale = `0`,
		const QString &	filterExp = `QString()`,
		const QString &	description = `QString()`,
		bool	elseRule = `false`
	)

takes ownership of settings, settings may be nullptr

Definition at line 63 of file qgsrulebasedlabeling.cpp.

◆ ~Rule()

QgsRuleBasedLabeling::Rule::~Rule ( )

Definition at line 77 of file qgsrulebasedlabeling.cpp.

◆ Rule() [2/2]

QgsRuleBasedLabeling::Rule::Rule ( const Rule & rh )

delete

Member Function Documentation

◆ accept()

bool QgsRuleBasedLabeling::Rule::accept ( QgsStyleEntityVisitorInterface * visitor ) const

Accepts the specified symbology visitor, causing it to visit all child rules associated with the rule.

Returns true if the visitor should continue visiting other objects, or false if visiting should be canceled.

Since: QGIS 3.10

Definition at line 145 of file qgsrulebasedlabeling.cpp.

◆ active()

bool QgsRuleBasedLabeling::Rule::active ( ) const

inline

Returns if this rule is active.

Returns: true if the rule is active

Definition at line 122 of file qgsrulebasedlabeling.h.

◆ appendChild()

void QgsRuleBasedLabeling::Rule::appendChild ( QgsRuleBasedLabeling::Rule * rule )

add child rule, take ownership, sets this as parent

Definition at line 185 of file qgsrulebasedlabeling.cpp.

◆ children() [1/2]

QgsRuleBasedLabeling::RuleList & QgsRuleBasedLabeling::Rule::children ( )

inline

Returns all children rules of this rule.

Returns: A list of rules

Definition at line 199 of file qgsrulebasedlabeling.h.

◆ children() [2/2]

const QgsRuleBasedLabeling::RuleList & QgsRuleBasedLabeling::Rule::children ( ) const

inline

Returns all children rules of this rule.

Returns: A list of rules

Definition at line 192 of file qgsrulebasedlabeling.h.

◆ clone()

QgsRuleBasedLabeling::Rule * QgsRuleBasedLabeling::Rule::clone ( bool resetRuleKey = true ) const

clone this rule

Parameters

resetRuleKey true if this rule and its children rule key need to be reset to new unique ones.

Returns: new instance

Definition at line 236 of file qgsrulebasedlabeling.cpp.

◆ create()

QgsRuleBasedLabeling::Rule * QgsRuleBasedLabeling::Rule::create	(	const QDomElement &	ruleElem,
		const QgsReadWriteContext &	context,
		bool	reuseId = `true`
	)

static

Create a rule from an XML definition.

Parameters

ruleElem	The XML rule element
context	reading context
reuseId	set to `true` to create an exact copy of the original symbol or `false` to create a new rule with the same parameters as the original but a new unique ruleKey(). (Since QGIS 3.30)

Returns: A new rule

Definition at line 251 of file qgsrulebasedlabeling.cpp.

◆ createSubProviders()

void QgsRuleBasedLabeling::Rule::createSubProviders	(	QgsVectorLayer *	layer,
		QgsRuleBasedLabeling::RuleToProviderVec &	subProviders,
		QgsRuleBasedLabelProvider *	provider
	)

add providers

Note: not available in Python bindings

Definition at line 323 of file qgsrulebasedlabeling.cpp.

◆ dependsOnScale()

bool QgsRuleBasedLabeling::Rule::dependsOnScale ( ) const

inline

Determines if scale based labeling is active.

Returns: true if scale based labeling is active

Definition at line 84 of file qgsrulebasedlabeling.h.

◆ descendants()

QgsRuleBasedLabeling::RuleList QgsRuleBasedLabeling::Rule::descendants ( ) const

Returns all children, grand-children, grand-grand-children, grand-gra... you get it.

Returns: A list of descendant rules

Definition at line 91 of file qgsrulebasedlabeling.cpp.

◆ description()

QString QgsRuleBasedLabeling::Rule::description ( ) const

inline

A human readable description for this rule.

Returns: Description

Definition at line 115 of file qgsrulebasedlabeling.h.

◆ filterExpression()

QString QgsRuleBasedLabeling::Rule::filterExpression ( ) const

inline

A filter that will check if this rule applies.

Returns: An expression

Definition at line 108 of file qgsrulebasedlabeling.h.

◆ findRuleByKey() [1/2]

QgsRuleBasedLabeling::Rule * QgsRuleBasedLabeling::Rule::findRuleByKey ( const QString & key )

Find a labeling rule thanks to its key.

Parameters

key	The key of the rule to find

Returns: The rule or nullptr if not found

Definition at line 222 of file qgsrulebasedlabeling.cpp.

◆ findRuleByKey() [2/2]

const QgsRuleBasedLabeling::Rule * QgsRuleBasedLabeling::Rule::findRuleByKey ( const QString & key ) const

Try to find a rule given its unique key.

Definition at line 206 of file qgsrulebasedlabeling.cpp.

◆ insertChild()

void QgsRuleBasedLabeling::Rule::insertChild	(	int	i,
		QgsRuleBasedLabeling::Rule *	rule
	)

add child rule, take ownership, sets this as parent

Definition at line 192 of file qgsrulebasedlabeling.cpp.

◆ isElse()

bool QgsRuleBasedLabeling::Rule::isElse ( ) const

inline

Check if this rule is an ELSE rule.

Returns: true if this rule is an else rule

Definition at line 129 of file qgsrulebasedlabeling.h.

◆ maximumScale()

double QgsRuleBasedLabeling::Rule::maximumScale ( ) const

inline

Returns the maximum map scale (i.e.

most "zoomed in" scale) at which the label rule will be active. The scale value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map. A scale of 0 indicates no maximum scale visibility.

See also: minimumScale(); setMaximumScale()

Definition at line 93 of file qgsrulebasedlabeling.h.

◆ minimumScale()

double QgsRuleBasedLabeling::Rule::minimumScale ( ) const

inline

Returns the minimum map scale (i.e.

most "zoomed out" scale) at which the label rule will be active. The scale value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map. A scale of 0 indicates no minimum scale visibility.

See also: maximumScale(); setMinimumScale()

Definition at line 102 of file qgsrulebasedlabeling.h.

◆ operator=()

Rule & QgsRuleBasedLabeling::Rule::operator= ( const Rule & rh )

delete

◆ parent() [1/2]

QgsRuleBasedLabeling::Rule * QgsRuleBasedLabeling::Rule::parent ( )

inline

The parent rule.

Returns: Parent rule

Definition at line 220 of file qgsrulebasedlabeling.h.

◆ parent() [2/2]

const QgsRuleBasedLabeling::Rule * QgsRuleBasedLabeling::Rule::parent ( ) const

inline

The parent rule.

Returns: Parent rule

Definition at line 213 of file qgsrulebasedlabeling.h.

◆ prepare()

void QgsRuleBasedLabeling::Rule::prepare	(	QgsRenderContext &	context,
		QSet< QString > &	attributeNames,
		QgsRuleBasedLabeling::RuleToProviderVec &	subProviders
	)

call prepare() on sub-providers and populate attributeNames

Note: not available in Python bindings

Definition at line 351 of file qgsrulebasedlabeling.cpp.

◆ registerFeature()

std::tuple< QgsRuleBasedLabeling::Rule::RegisterResult, QList< QgsLabelFeature * > > QgsRuleBasedLabeling::Rule::registerFeature	(	const QgsFeature &	feature,
		QgsRenderContext &	context,
		QgsRuleBasedLabeling::RuleToProviderVec &	subProviders,
		const QgsGeometry &	obstacleGeometry = `QgsGeometry()`,
		const QgsSymbol *	symbol = `nullptr`
	)

Register individual features.

Returns result of registration, together with a list of all label features which were created as a result of registering feature. Ownership of these label features is not transferred (it has already been assigned to the label provider).

Note: not available in Python bindings

Definition at line 385 of file qgsrulebasedlabeling.cpp.

◆ removeChildAt()

void QgsRuleBasedLabeling::Rule::removeChildAt ( int i )

delete child rule

Definition at line 199 of file qgsrulebasedlabeling.cpp.

◆ requiresAdvancedEffects()

bool QgsRuleBasedLabeling::Rule::requiresAdvancedEffects ( ) const

Returns true if this rule or any of its children requires advanced composition effects to render.

Definition at line 131 of file qgsrulebasedlabeling.cpp.

◆ ruleKey()

QString QgsRuleBasedLabeling::Rule::ruleKey ( ) const

inline

Unique rule identifier (for identification of rule within labeling, used as provider ID)

Definition at line 132 of file qgsrulebasedlabeling.h.

◆ save()

QDomElement QgsRuleBasedLabeling::Rule::save	(	QDomDocument &	doc,
		const QgsReadWriteContext &	context
	)		const

store labeling info to XML element

Definition at line 295 of file qgsrulebasedlabeling.cpp.

◆ setActive()

void QgsRuleBasedLabeling::Rule::setActive ( bool state )

inline

Sets if this rule is active.

Parameters

state Determines if the rule should be activated or deactivated

Definition at line 173 of file qgsrulebasedlabeling.h.

◆ setDescription()

void QgsRuleBasedLabeling::Rule::setDescription ( const QString & description )

inline

Set a human readable description for this rule.

Parameters

description Description

Definition at line 167 of file qgsrulebasedlabeling.h.

◆ setFilterExpression()

void QgsRuleBasedLabeling::Rule::setFilterExpression ( const QString & filterExp )

inline

Set the expression used to check if a given feature shall be rendered with this rule.

Parameters

filterExp An expression

Definition at line 160 of file qgsrulebasedlabeling.h.

◆ setIsElse()

void QgsRuleBasedLabeling::Rule::setIsElse ( bool iselse )

inline

Sets if this rule is an ELSE rule.

Parameters

iselse If true, this rule is an ELSE rule

Definition at line 180 of file qgsrulebasedlabeling.h.

◆ setMaximumScale()

void QgsRuleBasedLabeling::Rule::setMaximumScale ( double scale )

inline

Sets the maximum map scale (i.e.

most "zoomed in" scale) at which the rule will be active. The scale value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map. A scale of 0 indicates no maximum scale visibility.

See also: maximumScale(); setMinimumScale()

Definition at line 153 of file qgsrulebasedlabeling.h.

◆ setMinimumScale()

void QgsRuleBasedLabeling::Rule::setMinimumScale ( double scale )

inline

Sets the minimum map scale (i.e.

most "zoomed out" scale) at which the label rule will be active. The scale value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map. A scale of 0 indicates no minimum scale visibility.

See also: minimumScale(); setMaximumScale()

Definition at line 144 of file qgsrulebasedlabeling.h.

◆ setRuleKey()

void QgsRuleBasedLabeling::Rule::setRuleKey ( const QString & key )

inline

Override the assigned rule key (should be used just internally by rule-based labeling)

Definition at line 183 of file qgsrulebasedlabeling.h.

◆ setSettings()

void QgsRuleBasedLabeling::Rule::setSettings ( QgsPalLayerSettings * settings )

Sets new settings (or nullptr). Deletes old settings if any.

Definition at line 83 of file qgsrulebasedlabeling.cpp.

◆ settings()

QgsPalLayerSettings * QgsRuleBasedLabeling::Rule::settings ( ) const

inline

Returns the labeling settings.

May return nullptr.

Definition at line 77 of file qgsrulebasedlabeling.h.

◆ subProviderIds()

void QgsRuleBasedLabeling::Rule::subProviderIds ( QStringList & list ) const

append rule keys of descendants that contain valid settings (i.e.

they will be sub-providers)

Note: not available in Python bindings

Definition at line 173 of file qgsrulebasedlabeling.cpp.

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

/build/qgis-3.41.0+git20250218+64d82d4c163+99sid/src/core/labeling/qgsrulebasedlabeling.h
/build/qgis-3.41.0+git20250218+64d82d4c163+99sid/src/core/labeling/qgsrulebasedlabeling.cpp

Public Types

Public Member Functions

Static Public Member Functions

Detailed Description

Member Enumeration Documentation

◆ RegisterResult

Constructor & Destructor Documentation

◆ Rule() [1/2]

◆ ~Rule()

◆ Rule() [2/2]

Member Function Documentation

◆ accept()

◆ active()

◆ appendChild()

◆ children() [1/2]

◆ children() [2/2]

◆ clone()

◆ create()

◆ createSubProviders()

◆ dependsOnScale()

◆ descendants()

◆ description()

◆ filterExpression()

◆ findRuleByKey() [1/2]

◆ findRuleByKey() [2/2]

◆ insertChild()

◆ isElse()

◆ maximumScale()

◆ minimumScale()

◆ operator=()

◆ parent() [1/2]

◆ parent() [2/2]

◆ prepare()

◆ registerFeature()

◆ removeChildAt()

◆ requiresAdvancedEffects()

◆ ruleKey()

◆ save()

◆ setActive()

◆ setDescription()

◆ setFilterExpression()

◆ setIsElse()

◆ setMaximumScale()

◆ setMinimumScale()

◆ setRuleKey()

◆ setSettings()

◆ settings()

◆ subProviderIds()