Class: QgsMergedFeatureRenderer

A polygon or line-only feature renderer used to render a set of features merged (or dissolved) into a single geometry.

It is designed on top of another feature renderer, which is called “embedded” Most of the methods are then only proxies to the embedded renderer. E.g. if the embedded renderer is a categorized renderer, then all the matching features for each categorized class will be dissolved together. Features from different classes will NOT be dissolved together.

Added in version 3.18.

Class Hierarchy

Base classes

QgsFeatureRenderer

Abstract base class for all 2D vector feature renderers.

Subclasses

QgsInvertedPolygonRenderer

A polygon-only feature renderer used to display features inverted.

Virtual Methods

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

renderFeature	Renders a given feature.
stopRender	The actual rendering will take place here.

Static Methods

convertFromRenderer	Creates a QgsMergedFeatureRenderer by a conversion from an existing renderer.
create	Creates a renderer out of an XML, for loading

Attributes

InvertOnly
Merge
MergeAndInvert

class qgis.core.QgsMergedFeatureRenderer

Bases: QgsFeatureRenderer

__init__(embeddedRenderer: QgsFeatureRenderer | None)

Constructor for QgsMergedFeatureRenderer.

Parameters:

embeddedRenderer (Optional[QgsFeatureRenderer]) – optional embeddedRenderer. Ownership will be transferred.

__init__(type: str | None, embeddedRenderer: QgsFeatureRenderer | None)

Constructor for QgsMergedFeatureRenderer.

Parameters:

• type (Optional[str]) – renderer ID string

• embeddedRenderer (Optional[QgsFeatureRenderer]) – optional embeddedRenderer. Ownership will be transferred.

class GeometryOperation

Bases: int

InvertOnly = 1

Merge = 0

MergeAndInvert = 2

static convertFromRenderer(renderer: QgsFeatureRenderer | None) → QgsMergedFeatureRenderer | None

Creates a QgsMergedFeatureRenderer by a conversion from an existing renderer.

Return type:

Optional[QgsMergedFeatureRenderer]

Returns:

a new renderer if the conversion was possible, otherwise None.

Parameters:

renderer (Optional[QgsFeatureRenderer])

static create(element: QDomElement, context: QgsReadWriteContext) → QgsFeatureRenderer | None

Creates a renderer out of an XML, for loading

Parameters:

• element (QDomElement)

• context (QgsReadWriteContext)

Return type:

Optional[QgsFeatureRenderer]

virtual renderFeature(self, feature: QgsFeature, context: QgsRenderContext, layer: int = -1, selected: bool = False, drawVertexMarker: bool = False) → bool

Renders a given feature. This will here collect features. The actual rendering will be postponed to stopRender()

Parameters:

• feature (QgsFeature) – the feature to render

• context (QgsRenderContext) – the rendering context

• layer (int = -1) – the symbol layer to render, if that makes sense

• selected (bool = False) – whether this feature has been selected (this will add decorations)

• drawVertexMarker (bool = False) – whether this feature has vertex markers (in edit mode usually)

Return type:

bool

Returns:

True if the rendering was OK

virtual stopRender(self, context: QgsRenderContext)

The actual rendering will take place here. Features collected during renderFeature() are rendered using the embedded feature renderer

Parameters:

context (QgsRenderContext)