Class: QgsStyleEntityVisitorInterface¶

An interface for classes which can visit style entity (e.g. symbol) nodes (using the visitor pattern).

Added in version 3.10.

Enums

NodeType

Describes the types of nodes which may be visited by the visitor.

Virtual Methods

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

`visit`	Called when the visitor will visit a style entity.
`visitEnter`	Called when the visitor starts visiting a node.
`visitExit`	Called when the visitor stops visiting a node.

class qgis.core.QgsStyleEntityVisitorInterface[source]¶

Bases: object

class Node¶

Bases: object

Contains information relating to a node (i.e. a group of symbols or other nodes) being visited.

description: str¶: A string describing the node. The actual value of description will vary depending on the node being visited. E.g for a rule based renderer, the identifier will be a rule label. For a project, node identifiers will be layer names.

identifier: str¶: A string identifying the node. The actual value of identifier will vary depending on the node being visited. E.g for a rule based renderer, the identifier will be a rule ID. For a project, node identifiers will be layer IDs.

type: NodeType¶: Node type.

class NodeType(*values)¶

Bases: IntEnum

Describes the types of nodes which may be visited by the visitor.

Project: QGIS Project node
Layer: Map layer
SymbolRule: Rule based symbology or label child rule
Layouts: Layout collection
PrintLayout: An individual print layout
LayoutItem: Individual item in a print layout
Report: A QGIS print report
ReportHeader: Report header section
ReportFooter: Report footer section
ReportSection: Report sub section
Annotations: Annotations collection
Annotation: An individual annotation

Annotation = 11¶

Annotations = 10¶

Layer = 1¶

LayoutItem = 5¶

Layouts = 3¶

PrintLayout = 4¶

Project = 0¶

Report = 6¶

ReportFooter = 8¶

ReportHeader = 7¶

ReportSection = 9¶

SymbolRule = 2¶

class StyleLeaf¶

Bases: object

Contains information relating to the style entity currently being visited.

description: str¶

A string describing the style entity. The actual value of description will vary depending on the class being visited. E.g for a categorized renderer, the description will be the category label associated with the symbol, for a print layout, it will be the name of the layout in the project.

This may be blank if no description is associated with a style entity, e.g. when a renderer has a single symbol only.

This value may be a generic, translated value in some cases, e.g. “Grid” or “Overview”.

entity: QgsStyleEntityInterface¶: Reference to style entity being visited.

identifier: str¶

A string identifying the style entity. The actual value of identifier will vary depending on the class being visited. E.g for a categorized renderer, the identifier will be the category ID associated with the symbol.

This may be blank if no identifier is required, e.g. when a renderer has a single symbol only.

Note that in some cases where a specific identifier is not available, a generic, untranslated one may be used (e.g. “overview”, “grid”).

virtual visit(self, entity: QgsStyleEntityVisitorInterface.StyleLeaf) → bool[source]¶

Called when the visitor will visit a style entity.

Subclasses should return False to abort further visitations, or True to continue visiting after processing this entity.

Parameters:: entity (QgsStyleEntityVisitorInterface.StyleLeaf)
Return type:: bool

virtual visitEnter(self, node: QgsStyleEntityVisitorInterface.Node) → bool[source]¶

Called when the visitor starts visiting a node.

Subclasses should return False if they do NOT want to visit this particular node - e.g. if the node type is QgsStyleEntityVisitorInterface.NodeType.Layouts and they do not wish to visit layout objects. In this case the visitor will not process the node, and will move to the next available node instead. Return True to proceed with visiting the node.

The default implementation returns True.

Parameters:: node (QgsStyleEntityVisitorInterface.Node)
Return type:: bool

virtual visitExit(self, node: QgsStyleEntityVisitorInterface.Node) → bool[source]¶

Called when the visitor stops visiting a node.

Subclasses should return False to abort further visitations, or True to continue visiting other nodes.

The default implementation returns True.

Parameters:: node (QgsStyleEntityVisitorInterface.Node)
Return type:: bool