QgsRuleBasedLabeling::Rule class

Reference

Public types

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

Public static functions

static auto create(const QDomElement& ruleElem, const QgsReadWriteContext& context) -> QgsRuleBasedLabeling::Rule*: Create a rule from an XML definition.

Constructors, destructors, conversion operators

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(const Rule& rh) deleted: Rules cannot be copied.

Public functions

auto active() const -> bool: Returns if this rule is active.
void appendChild(QgsRuleBasedLabeling::Rule* rule): add child rule, take ownership, sets this as parent
auto children() const -> const QgsRuleBasedLabeling::RuleList&: Returns all children rules of this rule.
auto children() -> QgsRuleBasedLabeling::RuleList&: Returns all children rules of this rule.
auto clone() const -> QgsRuleBasedLabeling::Rule*: clone this rule, return new instance
void createSubProviders(QgsVectorLayer* layer, RuleToProviderMap& subProviders, QgsRuleBasedLabelProvider* provider): add providers
auto dependsOnScale() const -> bool: Determines if scale based labeling is active.
auto descendants() const -> QgsRuleBasedLabeling::RuleList: Returns all children, grand-children, grand-grand-children, grand-gra...
auto description() const -> QString: A human readable description for this rule.
auto filterExpression() const -> QString: A filter that will check if this rule applies.
auto findRuleByKey(const QString& key) const -> const QgsRuleBasedLabeling::Rule*: Try to find a rule given its unique key.
auto findRuleByKey(const QString& key) -> QgsRuleBasedLabeling::Rule*: Find a labeling rule thanks to its key.
void insertChild(int i, QgsRuleBasedLabeling::Rule* rule): add child rule, take ownership, sets this as parent
auto isElse() const -> bool: Check if this rule is an ELSE rule.
auto maximumScale() const -> double: Returns the maximum map scale (i.e.
auto minimumScale() const -> double: Returns the minimum map scale (i.e.
auto operator=(const Rule& rh) -> Rule& deleted: Rules cannot be copied.
auto parent() const -> const QgsRuleBasedLabeling::Rule*: The parent rule.
auto parent() -> QgsRuleBasedLabeling::Rule*: The parent rule.
void prepare(const QgsRenderContext& context, QSet<QString>& attributeNames, RuleToProviderMap& subProviders): call prepare() on sub-providers and populate attributeNames
auto registerFeature(QgsFeature& feature, QgsRenderContext& context, RuleToProviderMap& subProviders, const QgsGeometry& obstacleGeometry = QgsGeometry()) -> RegisterResult: register individual features
void removeChildAt(int i): delete child rule
auto requiresAdvancedEffects() const -> bool: Returns true if this rule or any of its children requires advanced composition effects to render.
auto ruleKey() const -> QString: Unique rule identifier (for identification of rule within labeling, used as provider ID)
auto save(QDomDocument& doc, const QgsReadWriteContext& context) const -> QDomElement: 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 NULL). Deletes old settings if any.
auto settings() const -> QgsPalLayerSettings*: Gets the labeling settings.
void subProviderIds(QStringList& list) const: append rule keys of descendants that contain valid settings (i.e.

Enum documentation

enum QgsRuleBasedLabeling::Rule::RegisterResult

The result of registering a rule.

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

Function documentation

static QgsRuleBasedLabeling::Rule* QgsRuleBasedLabeling::Rule::create(const QDomElement& ruleElem, const QgsReadWriteContext& context)

Create a rule from an XML definition.

Parameters
ruleElem	The XML rule element
context	reading context
Returns	A new rule

bool QgsRuleBasedLabeling::Rule::active() const

Returns if this rule is active.

Returns	True if the rule is active

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

Returns all children rules of this rule.

Returns	A list of rules

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

Returns all children rules of this rule.

Returns	A list of rules

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

add providers

bool QgsRuleBasedLabeling::Rule::dependsOnScale() const

Determines if scale based labeling is active.

Returns	True if scale based labeling is active

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

Returns all children, grand-children, grand-grand-children, grand-gra...

Returns	A list of descendant rules

you get it

QString QgsRuleBasedLabeling::Rule::description() const

A human readable description for this rule.

Returns	Description

QString QgsRuleBasedLabeling::Rule::filterExpression() const

A filter that will check if this rule applies.

Returns	An expression

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 a nullptr if not found

bool QgsRuleBasedLabeling::Rule::isElse() const

Check if this rule is an ELSE rule.

Returns	True if this rule is an else rule

double QgsRuleBasedLabeling::Rule::maximumScale() const

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.

double QgsRuleBasedLabeling::Rule::minimumScale() const

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.

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

The parent rule.

Returns	Parent rule

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

The parent rule.

Returns	Parent rule

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

call prepare() on sub-providers and populate attributeNames

RegisterResult QgsRuleBasedLabeling::Rule::registerFeature(QgsFeature& feature, QgsRenderContext& context, RuleToProviderMap& subProviders, const QgsGeometry& obstacleGeometry = QgsGeometry())

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

Sets if this rule is active.

Parameters
state	Determines if the rule should be activated or deactivated

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

Set a human readable description for this rule.

Parameters
description	Description

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

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

Parameters
filterExp	An expression

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

Sets if this rule is an ELSE rule.

Parameters
iselse	If true, this rule is an ELSE rule

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

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.

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

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.

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

Gets the labeling settings.

May return a null pointer.

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

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

they will be sub-providers)