Class: QgsRuleBasedLabeling

class qgis.core.QgsRuleBasedLabeling(root: QgsRuleBasedLabeling.Rule)

Bases: QgsAbstractVectorLayerLabeling

Constructs the labeling from given tree of rules (takes ownership)

New in version 3.0.

Parameters

root

class Rule(settings: QgsPalLayerSettings, maximumScale: float = 0, minimumScale: float = 0, filterExp: str = '', description: str = '', elseRule: bool = False)

Bases: sip.wrapper

takes ownership of settings, settings may be None

New in version 3.0.

Parameters
  • settings (QgsPalLayerSettings) –

  • maximumScale (float = 0) –

  • minimumScale (float = 0) –

  • filterExp (str = '') –

  • description (str = '') –

  • elseRule (bool = False) –

Filtered = 0
Inactive = 1
class RegisterResult

Bases: int

Registered = 2
accept(self, visitor: QgsStyleEntityVisitorInterface) → bool

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.

New in version 3.10.

Parameters

visitor (QgsStyleEntityVisitorInterface) –

Return type

bool

active(self) → bool

Returns if this rule is active

Return type

bool

Returns

True if the rule is active

appendChild(self, rule: QgsRuleBasedLabeling.Rule)

add child rule, take ownership, sets this as parent

Parameters

rule (QgsRuleBasedLabeling.Rule) –

children(self) → List[QgsRuleBasedLabeling.Rule]

Returns all children rules of this rule

Return type

List[QgsRuleBasedLabeling.Rule]

Returns

A list of rules

clone(self) → QgsRuleBasedLabeling.Rule

clone this rule, return new instance

Return type

QgsRuleBasedLabeling.Rule

create(ruleElem: QDomElement, context: QgsReadWriteContext) → QgsRuleBasedLabeling.Rule

Create a rule from an XML definition

Parameters
  • ruleElem (QDomElement) – The XML rule element

  • context (QgsReadWriteContext) – reading context

Return type

QgsRuleBasedLabeling.Rule

Returns

A new rule

dependsOnScale(self) → bool

Determines if scale based labeling is active

Return type

bool

Returns

True if scale based labeling is active

descendants(self) → List[QgsRuleBasedLabeling.Rule]

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

Return type

List[QgsRuleBasedLabeling.Rule]

Returns

A list of descendant rules

description(self) → str

A human readable description for this rule

Return type

str

Returns

Description

filterExpression(self) → str

A filter that will check if this rule applies

Return type

str

Returns

An expression

findRuleByKey(self, key: str) → QgsRuleBasedLabeling.Rule

Try to find a rule given its unique key

Parameters

key (str) –

Return type

QgsRuleBasedLabeling.Rule

insertChild(self, i: int, rule: QgsRuleBasedLabeling.Rule)

add child rule, take ownership, sets this as parent

Parameters
isElse(self) → bool

Check if this rule is an ELSE rule

Return type

bool

Returns

True if this rule is an else rule

maximumScale(self) → float

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()

New in version 3.0.

Return type

float

minimumScale(self) → float

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()

New in version 3.0.

Return type

float

parent(self) → QgsRuleBasedLabeling.Rule

The parent rule

Return type

QgsRuleBasedLabeling.Rule

Returns

Parent rule

removeChildAt(self, i: int)

delete child rule

Parameters

i (int) –

requiresAdvancedEffects(self) → bool

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

Return type

bool

ruleKey(self) → str

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

Return type

str

save(self, doc: QDomDocument, context: QgsReadWriteContext) → QDomElement

store labeling info to XML element

Parameters
Return type

QDomElement

setActive(self, state: bool)

Sets if this rule is active

Parameters

state (bool) – Determines if the rule should be activated or deactivated

setDescription(self, description: str)

Set a human readable description for this rule

Parameters

description (str) – Description

setFilterExpression(self, filterExp: str)

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

Parameters

filterExp (str) – An expression

setIsElse(self, iselse: bool)

Sets if this rule is an ELSE rule

Parameters

iselse (bool) – If True, this rule is an ELSE rule

setMaximumScale(self, scale: float)

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()

Parameters

scale (float) –

setMinimumScale(self, scale: float)

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()

Parameters

scale (float) –

setRuleKey(self, key: str)

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

Parameters

key (str) –

setSettings(self, settings: QgsPalLayerSettings)

Sets new settings (or None). Deletes old settings if any.

Parameters

settings (QgsPalLayerSettings) –

settings(self) → QgsPalLayerSettings

Returns the labeling settings. May return None.

Return type

QgsPalLayerSettings

accept(self, visitor: QgsStyleEntityVisitorInterface) → bool
Parameters

visitor (QgsStyleEntityVisitorInterface) –

Return type

bool

clone(self) → QgsRuleBasedLabeling
Return type

QgsRuleBasedLabeling

create(element: QDomElement, context: QgsReadWriteContext) → QgsRuleBasedLabeling

Create the instance from a DOM element with saved configuration

Parameters
Return type

QgsRuleBasedLabeling

requiresAdvancedEffects(self) → bool
Return type

bool

rootRule(self) → QgsRuleBasedLabeling.Rule
Return type

QgsRuleBasedLabeling.Rule

save(self, doc: QDomDocument, context: QgsReadWriteContext) → QDomElement
Parameters
Return type

QDomElement

setSettings(self, settings: QgsPalLayerSettings, providerId: str = '')

Set pal settings for a specific provider (takes ownership).

Parameters
  • settings (QgsPalLayerSettings) – Pal layer settings

  • providerId (str = '') – The id of the provider

New in version 3.0.

settings(self, providerId: str = '') → QgsPalLayerSettings
Parameters

providerId (str = '') –

Return type

QgsPalLayerSettings

subProviders(self) → List[str]
Return type

List[str]

toSld(self, parent: QDomNode, props: Dict[str, str])
Parameters
  • parent (QDomNode) –

  • props (Dict[str) –

type(self) → str
Return type

str

writeTextSymbolizer()