Null symbol renderer, which draws no symbols for features by default, but allows for labeling and diagrams for the layer. More...

#include <qgsnullsymbolrenderer.h>

Inheritance diagram for QgsNullSymbolRenderer:

[legend]

Public Member Functions
	QgsNullSymbolRenderer ()

	~QgsNullSymbolRenderer ()

QgsFeatureRenderer *	clone () const override
	Create a deep copy of this renderer.

QString	dump () const override
	Returns debug information about this renderer.

QgsSymbol *	originalSymbolForFeature (const QgsFeature &feature, QgsRenderContext &context) const override
	Returns symbol for feature.

bool	renderFeature (const QgsFeature &feature, QgsRenderContext &context, int layer=-1, bool selected=false, bool drawVertexMarker=false) override
	Render a feature using this renderer in the given context.

QDomElement	save (QDomDocument &doc, const QgsReadWriteContext &context) override
	Stores renderer properties to an XML element.

void	stopRender (QgsRenderContext &context) override
	Must be called when a render cycle has finished, to allow the renderer to clean up.

QgsSymbol *	symbolForFeature (const QgsFeature &feature, QgsRenderContext &context) const override
	To be overridden.

QgsSymbolList	symbols (QgsRenderContext &context) const override
	Returns list of symbols used by the renderer.

QSet< QString >	usedAttributes (const QgsRenderContext &context) const override
	Returns a list of attributes required by this renderer.

bool	willRenderFeature (const QgsFeature &feature, QgsRenderContext &context) const override
	Returns whether the renderer will render a feature or not.

Public Member Functions inherited from QgsFeatureRenderer
virtual	~QgsFeatureRenderer ()

virtual bool	accept (QgsStyleEntityVisitorInterface *visitor) const
	Accepts the specified symbology visitor, causing it to visit all symbols associated with the renderer.

virtual bool	canSkipRender ()
	Returns `true` if the renderer can be entirely skipped, i.e.

virtual QgsFeatureRenderer::Capabilities	capabilities ()
	Returns details about internals of this renderer.

virtual void	checkLegendSymbolItem (const QString &key, bool state=true)
	Sets whether the legend symbology item with the specified ley should be checked.

void	copyRendererData (QgsFeatureRenderer *destRenderer) const
	Clones generic renderer data to another renderer.

virtual QList< QgsLayerTreeModelLegendNode * >	createLegendNodes (QgsLayerTreeLayer *nodeLayer) const
	Returns a list of legend nodes to be used for the legend for the renderer.

QgsPropertyCollection &	dataDefinedProperties ()
	Returns a reference to the renderer's property collection, used for data defined overrides.

const QgsPropertyCollection &	dataDefinedProperties () const
	Returns a reference to the renderer's property collection, used for data defined overrides.

virtual const QgsFeatureRenderer *	embeddedRenderer () const
	Returns the current embedded renderer (subrenderer) for this feature renderer.

virtual QString	filter (const QgsFields &fields=QgsFields())
	If a renderer does not require all the features this method may be overridden and return an expression used as where clause.

virtual bool	filterNeedsGeometry () const
	Returns `true` if this renderer requires the geometry to apply the filter.

virtual Qgis::FeatureRendererFlags	flags () const
	Returns flags associated with the renderer.

bool	forceRasterRender () const
	Returns whether the renderer must render as a raster.

virtual QString	legendClassificationAttribute () const
	If supported by the renderer, return classification attribute for the use in legend.

QSet< QString >	legendKeys () const
	Returns the set of all legend keys used by the renderer.

virtual QSet< QString >	legendKeysForFeature (const QgsFeature &feature, QgsRenderContext &context) const
	Returns legend keys matching a specified feature.

virtual QString	legendKeyToExpression (const QString &key, QgsVectorLayer *layer, bool &ok) const
	Attempts to convert the specified legend rule key to a QGIS expression matching the features displayed using that key.

virtual bool	legendSymbolItemChecked (const QString &key)
	Returns `true` if the legend symbology item with the specified key is checked.

virtual QgsLegendSymbolList	legendSymbolItems () const
	Returns a list of symbology items for the legend.

virtual bool	legendSymbolItemsCheckable () const
	Returns `true` if symbology items in legend are checkable.

double	maximumExtentBuffer (QgsRenderContext &context) const
	Returns the maximum extent buffer found in this renderer's symbols.

virtual void	modifyRequestExtent (QgsRectangle &extent, QgsRenderContext &context)
	Allows for a renderer to modify the extent of a feature request prior to rendering.

QgsFeatureRequest::OrderBy	orderBy () const
	Gets the order in which features shall be processed by this renderer.

bool	orderByEnabled () const
	Returns whether custom ordering will be applied before features are processed by this renderer.

virtual QgsSymbolList	originalSymbolsForFeature (const QgsFeature &feature, QgsRenderContext &context) const
	Equivalent of originalSymbolsForFeature() call extended to support renderers that may use more symbols per feature - similar to symbolsForFeature()

QgsPaintEffect *	paintEffect () const
	Returns the current paint effect for the renderer.

double	referenceScale () const
	Returns the symbology reference scale.

void	setDataDefinedProperties (const QgsPropertyCollection &collection)
	Sets the renderer's property collection, used for data defined overrides.

void	setDataDefinedProperty (Property key, const QgsProperty &property)
	Sets a data defined property for the renderer.

virtual void	setEmbeddedRenderer (QgsFeatureRenderer *subRenderer)
	Sets an embedded renderer (subrenderer) for this feature renderer.

void	setForceRasterRender (bool forceRaster)
	Sets whether the renderer should be rendered to a raster destination.

virtual void	setLegendSymbolItem (const QString &key, QgsSymbol *symbol)
	Sets the symbol to be used for a legend symbol item.

void	setOrderBy (const QgsFeatureRequest::OrderBy &orderBy)
	Define the order in which features shall be processed by this renderer.

void	setOrderByEnabled (bool enabled)
	Sets whether custom ordering should be applied before features are processed by this renderer.

void	setPaintEffect (QgsPaintEffect *effect)
	Sets the current paint effect for the renderer.

void	setReferenceScale (double scale)
	Sets the symbology reference scale.

void	setUsingSymbolLevels (bool usingSymbolLevels)

void	setVertexMarkerAppearance (Qgis::VertexMarkerType type, double size)
	Sets type and size of editing vertex markers for subsequent rendering.

virtual void	startRender (QgsRenderContext &context, const QgsFields &fields)
	Must be called when a new render cycle is started.

virtual QgsSymbolList	symbolsForFeature (const QgsFeature &feature, QgsRenderContext &context) const
	Returns list of symbols used for rendering the feature.

virtual void	toSld (QDomDocument &doc, QDomElement &element, const QVariantMap &props=QVariantMap()) const
	used from subclasses to create SLD Rule elements following SLD v1.1 specs

QString	type () const

virtual bool	usesEmbeddedSymbols () const
	Returns `true` if the renderer uses embedded symbols for features.

bool	usingSymbolLevels () const

virtual QDomElement	writeSld (QDomDocument &doc, const QString &styleName, const QVariantMap &props=QVariantMap()) const
	create the SLD UserStyle element following the SLD v1.1 specs with the given name

Static Public Member Functions
static QgsNullSymbolRenderer *	convertFromRenderer (const QgsFeatureRenderer *renderer)
	Creates a QgsNullSymbolRenderer from an existing renderer.

static QgsFeatureRenderer *	create (QDomElement &element, const QgsReadWriteContext &context)
	Creates a null renderer from XML element.

Static Public Member Functions inherited from QgsFeatureRenderer
static QgsFeatureRenderer *	defaultRenderer (Qgis::GeometryType geomType)
	Returns a new renderer - used by default in vector layers.

static QgsFeatureRenderer *	load (QDomElement &symbologyElem, const QgsReadWriteContext &context)
	create a renderer from XML element

static QgsFeatureRenderer *	loadSld (const QDomNode &node, Qgis::GeometryType geomType, QString &errorMessage)
	Create a new renderer according to the information contained in the UserStyle element of a SLD style document.

static const QgsPropertiesDefinition &	propertyDefinitions ()
	Returns the symbol property definitions.

Additional Inherited Members
Public Types inherited from QgsFeatureRenderer
typedef QFlags< Capability >	Capabilities

enum	Capability { SymbolLevels = 1 , MoreSymbolsPerFeature = 1 << 2 , Filter = 1 << 3 , ScaleDependent = 1 << 4 }
	Used to specify details about a renderer. More...

enum class	Property : int { HeatmapRadius , HeatmapMaximum }
	Data definable properties for renderers. More...

Protected Member Functions inherited from QgsFeatureRenderer
	QgsFeatureRenderer (const QString &type)

void	renderFeatureWithSymbol (const QgsFeature &feature, QgsSymbol *symbol, QgsRenderContext &context, int layer, bool selected, bool drawVertexMarker)
	Render the feature with the symbol using context.

void	renderVertexMarker (QPointF pt, QgsRenderContext &context)
	render editing vertex marker at specified point

void	renderVertexMarkerPolygon (QPolygonF &pts, QList< QPolygonF > *rings, QgsRenderContext &context)
	render editing vertex marker for a polygon

void	renderVertexMarkerPolyline (QPolygonF &pts, QgsRenderContext &context)
	render editing vertex marker for a polyline

void	saveRendererData (QDomDocument &doc, QDomElement &element, const QgsReadWriteContext &context)
	Saves generic renderer data into the specified element.

Static Protected Member Functions inherited from QgsFeatureRenderer
static QPointF	_getPoint (QgsRenderContext &context, const QgsPoint &point)
	Creates a point in screen coordinates from a wkb string in map coordinates.

static void	convertSymbolRotation (QgsSymbol *symbol, const QString &field)

static void	convertSymbolSizeScale (QgsSymbol *symbol, Qgis::ScaleMethod method, const QString &field)

Protected Attributes inherited from QgsFeatureRenderer
double	mCurrentVertexMarkerSize = 2
	The current size of editing marker.

Qgis::VertexMarkerType	mCurrentVertexMarkerType = Qgis::VertexMarkerType::Cross
	The current type of editing marker.

bool	mForceRaster = false

QgsFeatureRequest::OrderBy	mOrderBy

bool	mOrderByEnabled = false

QgsPaintEffect *	mPaintEffect = nullptr

double	mReferenceScale = -1.0

QString	mType

bool	mUsingSymbolLevels = false

Detailed Description

Null symbol renderer, which draws no symbols for features by default, but allows for labeling and diagrams for the layer.

Selected features will also be drawn with a default symbol.

Definition at line 32 of file qgsnullsymbolrenderer.h.

Constructor & Destructor Documentation

◆ QgsNullSymbolRenderer()

QgsNullSymbolRenderer::QgsNullSymbolRenderer ( )

Definition at line 23 of file qgsnullsymbolrenderer.cpp.

◆ ~QgsNullSymbolRenderer()

QgsNullSymbolRenderer::~QgsNullSymbolRenderer ( )

default

Member Function Documentation

◆ clone()

QgsFeatureRenderer * QgsNullSymbolRenderer::clone ( ) const

overridevirtual

Create a deep copy of this renderer.

Should be implemented by all subclasses and generate a proper subclass.

Returns: A copy of this renderer

Implements QgsFeatureRenderer.

Definition at line 91 of file qgsnullsymbolrenderer.cpp.

◆ convertFromRenderer()

QgsNullSymbolRenderer * QgsNullSymbolRenderer::convertFromRenderer ( const QgsFeatureRenderer * renderer )

static

Creates a QgsNullSymbolRenderer from an existing renderer.

Parameters

renderer renderer to convert from

Returns: a new renderer if the conversion was possible, otherwise nullptr.

Definition at line 122 of file qgsnullsymbolrenderer.cpp.

◆ create()

QgsFeatureRenderer * QgsNullSymbolRenderer::create	(	QDomElement &	element,
		const QgsReadWriteContext &	context
	)

static

Creates a null renderer from XML element.

Parameters

element	DOM element
context	reading context

Returns: new null symbol renderer

Definition at line 103 of file qgsnullsymbolrenderer.cpp.

◆ dump()

QString QgsNullSymbolRenderer::dump ( ) const

overridevirtual

Returns debug information about this renderer.

Reimplemented from QgsFeatureRenderer.

Definition at line 86 of file qgsnullsymbolrenderer.cpp.

◆ originalSymbolForFeature()

QgsSymbol * QgsNullSymbolRenderer::originalSymbolForFeature	(	const QgsFeature &	feature,
		QgsRenderContext &	context
	)		const

overridevirtual

Returns symbol for feature.

The difference compared to symbolForFeature() is that it returns original symbol which can be used as an identifier for renderer's rule - the former may return a temporary replacement of a symbol for use in rendering.

Reimplemented from QgsFeatureRenderer.

Definition at line 35 of file qgsnullsymbolrenderer.cpp.

◆ renderFeature()

bool QgsNullSymbolRenderer::renderFeature	(	const QgsFeature &	feature,
		QgsRenderContext &	context,
		int	layer = `-1`,
		bool	selected = `false`,
		bool	drawVertexMarker = `false`
	)

overridevirtual

Render a feature using this renderer in the given context.

Must be called between startRender() and stopRender() calls. Default implementation renders a symbol as determined by symbolForFeature() call. Returns true if the feature has been returned (this is used for example to determine whether the feature may be labelled).

If layer is not -1, the renderer should draw only a particular layer from symbols (in order to support symbol level rendering).

See also: startRender(); stopRender()

Reimplemented from QgsFeatureRenderer.

Definition at line 40 of file qgsnullsymbolrenderer.cpp.

◆ save()

QDomElement QgsNullSymbolRenderer::save	(	QDomDocument &	doc,
		const QgsReadWriteContext &	context
	)

overridevirtual

Stores renderer properties to an XML element.

Subclasses which override this method should call saveRendererData() as part of their implementation in order to store all common base class properties in the returned DOM element.

Reimplemented from QgsFeatureRenderer.

Definition at line 111 of file qgsnullsymbolrenderer.cpp.

◆ stopRender()

void QgsNullSymbolRenderer::stopRender ( QgsRenderContext & context )

overridevirtual

Must be called when a render cycle has finished, to allow the renderer to clean up.

Calls to stopRender() must always be preceded by a call to startRender().

Warning: This method is not thread safe. Before calling startRender() in a non-main thread, the renderer should instead be cloned and startRender()/stopRender() called on the clone.

See also: startRender()

Reimplemented from QgsFeatureRenderer.

Definition at line 65 of file qgsnullsymbolrenderer.cpp.

◆ symbolForFeature()

QgsSymbol * QgsNullSymbolRenderer::symbolForFeature	(	const QgsFeature &	feature,
		QgsRenderContext &	context
	)		const

overridevirtual

To be overridden.

Must be called between startRender() and stopRender() calls.

Parameters

feature	feature
context	render context

Returns: returns pointer to symbol or 0 if symbol was not found

Implements QgsFeatureRenderer.

Definition at line 30 of file qgsnullsymbolrenderer.cpp.

◆ symbols()

QgsSymbolList QgsNullSymbolRenderer::symbols ( QgsRenderContext & context ) const

overridevirtual

Returns list of symbols used by the renderer.

Parameters

context render context

Reimplemented from QgsFeatureRenderer.

Definition at line 98 of file qgsnullsymbolrenderer.cpp.

◆ usedAttributes()

QSet< QString > QgsNullSymbolRenderer::usedAttributes ( const QgsRenderContext & context ) const

overridevirtual

Returns a list of attributes required by this renderer.

Attributes not listed in here may not have been requested from the provider at rendering time.

Returns: A set of attributes

Implements QgsFeatureRenderer.

Definition at line 81 of file qgsnullsymbolrenderer.cpp.

◆ willRenderFeature()

bool QgsNullSymbolRenderer::willRenderFeature	(	const QgsFeature &	feature,
		QgsRenderContext &	context
	)		const

overridevirtual

Returns whether the renderer will render a feature or not.

Must be called between startRender() and stopRender() calls. Default implementation uses symbolForFeature().

Reimplemented from QgsFeatureRenderer.

Definition at line 75 of file qgsnullsymbolrenderer.cpp.

The documentation for this class was generated from the following files:

/build/qgis-3.41.0+git20241214+cea29feecf2+99sid/src/core/symbology/qgsnullsymbolrenderer.h
/build/qgis-3.41.0+git20241214+cea29feecf2+99sid/src/core/symbology/qgsnullsymbolrenderer.cpp

Public Member Functions

Static Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QgsNullSymbolRenderer()

◆ ~QgsNullSymbolRenderer()

Member Function Documentation

◆ clone()

◆ convertFromRenderer()

◆ create()

◆ dump()

◆ originalSymbolForFeature()

◆ renderFeature()

◆ save()

◆ stopRender()

◆ symbolForFeature()

◆ symbols()

◆ usedAttributes()

◆ willRenderFeature()