Class: QgsAbstractVectorLayerLabeling¶

Abstract base class - its implementations define different approaches to the labeling of a vector layer.

Note

This is an abstract class, with methods which must be implemented by a subclass.

The following methods must be implemented: clone(), hasNonDefaultCompositionMode(), requiresAdvancedEffects(), save(), setSettings(), settings(), type()

Class Hierarchy¶

Subclasses¶

`QgsRuleBasedLabeling`	Rule based labeling for a vector layer.
`QgsVectorLayerSimpleLabeling`	Basic implementation of the labeling interface.

Abstract Methods

`clone`	Returns a new copy of the object
`hasNonDefaultCompositionMode`	Returns `True` the labeling requires a non-default composition mode.
`requiresAdvancedEffects`	Returns `True` if drawing labels requires advanced effects like composition modes, which could prevent it being used as an isolated cached image or exported to a vector format.
`save`	Returns labeling configuration as XML element
`setSettings`	Set pal settings for a specific provider (takes ownership).
`settings`	Gets associated label settings.
`type`	Unique type string of the labeling configuration implementation

Virtual Methods

In PyQGIS, only methods marked as virtual can be safely overridden in a Python subclass of QgsAbstractVectorLayerLabeling. See the FAQ for more details.

`accept`	Accepts the specified symbology visitor, causing it to visit all symbols associated with the labeling.
`multiplyOpacity`	Multiply opacity by opacityFactor.
`subProviders`	Gets list of sub-providers within the layer's labeling.
`toSld`	Writes the SE 1.1 TextSymbolizer element based on the current layer labeling settings
`writeTextSymbolizer`	Writes a TextSymbolizer element contents based on the provided labeling settings

Static Methods

`create`	Try to create instance of an implementation based on the XML data
`defaultSettingsForLayer`	Returns the default layer settings to use for the specified vector layer.

class qgis.core.QgsAbstractVectorLayerLabeling[source]¶

Bases: object

virtual accept(self, visitor: QgsStyleEntityVisitorInterface | None) → bool[source]¶

Accepts the specified symbology visitor, causing it to visit all symbols associated with the labeling.

Returns True if the visitor should continue visiting other objects, or False if visiting should be canceled.

Added in version 3.10.

Parameters:: visitor (Optional[QgsStyleEntityVisitorInterface])
Return type:: bool

abstract clone(self) → QgsAbstractVectorLayerLabeling | None[source]¶

Returns a new copy of the object

Return type:: Optional[QgsAbstractVectorLayerLabeling]

static create(element: QDomElement, context: QgsReadWriteContext) → QgsAbstractVectorLayerLabeling | None[source]¶

Try to create instance of an implementation based on the XML data

Parameters:

element (QDomElement)
context (QgsReadWriteContext)

Return type:

Optional[QgsAbstractVectorLayerLabeling]

static defaultSettingsForLayer(layer: QgsVectorLayer | None) → QgsPalLayerSettings[source]¶

Returns the default layer settings to use for the specified vector layer.

Added in version 3.20.

Parameters:: layer (Optional[QgsVectorLayer])
Return type:: QgsPalLayerSettings

abstract hasNonDefaultCompositionMode(self) → bool[source]¶

Returns True the labeling requires a non-default composition mode.

This method is pessimistic, in that it will return True in cases where composition modes cannot be easily determined in advance (e.g. when data-defined overrides are in place for composition modes).

The default composition mode is QPainter.CompositionMode_SourceOver.

Added in version 3.44.

Return type:: bool

virtual multiplyOpacity(self, opacityFactor: float)[source]¶

Multiply opacity by opacityFactor.

This method multiplies the opacity of the labeling elements (text, shadow, buffer etc.) by opacity effectively changing the opacity of the whole labeling elements.

Added in version 3.32.

Parameters:: opacityFactor (float)

abstract requiresAdvancedEffects(self) → bool[source]¶

Returns True if drawing labels requires advanced effects like composition modes, which could prevent it being used as an isolated cached image or exported to a vector format.

Return type:: bool

abstract save(self, doc: QDomDocument, context: QgsReadWriteContext) → QDomElement[source]¶

Returns labeling configuration as XML element

Parameters:

doc (QDomDocument)
context (QgsReadWriteContext)

Return type:

QDomElement

abstract setSettings(self, settings: QgsPalLayerSettings | None, providerId: str | None = '')[source]¶

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

Parameters:

settings (Optional[QgsPalLayerSettings]) – Pal layer settings
providerId (Optional[str] = '') – The id of the provider

abstract settings(self, providerId: str | None = '') → QgsPalLayerSettings[source]¶

Gets associated label settings. In case of multiple sub-providers with different settings, they are identified by their ID (e.g. in case of rule-based labeling, provider ID == rule key)

Parameters:: providerId (Optional[str] = '')
Return type:: QgsPalLayerSettings

virtual subProviders(self) → List[str][source]¶

Gets list of sub-providers within the layer’s labeling.

Return type:: List[str]

virtual toSld(self, parent: QDomNode, props: Dict[str, Any])[source]¶

Writes the SE 1.1 TextSymbolizer element based on the current layer labeling settings

Deprecated since version 3.44: Use the version with QgsSldExportContext instead.

Parameters:

parent (QDomNode)
props (Dict[str, Any])

virtual toSld(self, parent: QDomNode, context: QgsSldExportContext) → bool[source]

Writes the SE 1.1 TextSymbolizer element based on the current layer labeling settings.

Added in version 3.44.

Parameters:

parent (QDomNode)
context (QgsSldExportContext)

Return type:

bool

abstract type(self) → str[source]¶

Unique type string of the labeling configuration implementation

Return type:: str

virtual writeTextSymbolizer(self, parent: QDomNode, settings: QgsPalLayerSettings, props: Dict[str, Any])[source]¶

Writes a TextSymbolizer element contents based on the provided labeling settings

Parameters:

parent (QDomNode) – the node that will have the text symbolizer element added to it
settings (QgsPalLayerSettings) – the settings getting translated to a TextSymbolizer
props (Dict[str, Any]) – a open ended set of properties that can drive/inform the SLD encoding

Deprecated since version 3.44: Use the version with QgsSldExportContext instead.

virtual writeTextSymbolizer(self, parent: QDomNode, settings: QgsPalLayerSettings, context: QgsSldExportContext) → bool[source]

Writes a TextSymbolizer element contents based on the provided labeling settings

Parameters:

parent (QDomNode) – the node that will have the text symbolizer element added to it
settings (QgsPalLayerSettings) – the settings getting translated to a TextSymbolizer
context (QgsSldExportContext) – export context

Added in version 3.44.

Return type:: bool