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

#include <qgsmergedfeaturerenderer.h>

Inheritance diagram for QgsMergedFeatureRenderer:

[legend]

Public Member Functions
	QgsMergedFeatureRenderer (const QgsMergedFeatureRenderer &)=delete
	Direct copies are forbidden. Use clone() instead. More...

	QgsMergedFeatureRenderer (QgsFeatureRenderer *embeddedRenderer)
	Constructor for QgsMergedFeatureRenderer. More...

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

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

void	checkLegendSymbolItem (const QString &key, bool state=true) override
	item in symbology was checked More...

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

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

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

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

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

bool	legendSymbolItemChecked (const QString &key) override
	items of symbology items in legend is checked More...

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

bool	legendSymbolItemsCheckable () const override
	items of symbology items in legend should be checkable More...

QgsMergedFeatureRenderer &	operator= (const QgsMergedFeatureRenderer &)=delete
	Direct copies are forbidden. Use clone() instead. More...

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

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

bool	renderFeature (const QgsFeature &feature, QgsRenderContext &context, int layer=-1, bool selected=false, bool drawVertexMarker=false) override SIP_THROW(QgsCsException)
	Renders a given feature. More...

QDomElement	save (QDomDocument &doc, const QgsReadWriteContext &context) override
	store renderer info to XML element More...

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

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

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

void	stopRender (QgsRenderContext &context) override
	The actual rendering will take place here. More...

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

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

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

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

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

Public Member Functions inherited from QgsFeatureRenderer
virtual	~QgsFeatureRenderer ()

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. More...

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

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

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

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

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

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

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

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

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

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

void	setUsingSymbolLevels (bool usingSymbolLevels)

void	setVertexMarkerAppearance (int type, double size)
	Sets type and size of editing vertex markers for subsequent rendering. More...

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 More...

QString	type () const

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

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 More...

Static Public Member Functions
static QgsMergedFeatureRenderer *	convertFromRenderer (const QgsFeatureRenderer *renderer)
	Creates a QgsMergedFeatureRenderer by a conversion from an existing renderer. More...

static QgsFeatureRenderer *	create (QDomElement &element, const QgsReadWriteContext &context)
	Creates a renderer out of an XML, for loading. More...

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

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

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

Protected Types
enum	GeometryOperation { Merge , InvertOnly , MergeAndInvert }
	Operations to apply to collected geometries prior to rendering. More...

Protected Member Functions
	QgsMergedFeatureRenderer (const QString &type, QgsFeatureRenderer *embeddedRenderer)
	Constructor for QgsMergedFeatureRenderer. More...

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

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

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

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

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

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

Protected Attributes
GeometryOperation	mOperation = Merge
	Operation to apply to collected geometries. More...

std::unique_ptr< QgsFeatureRenderer >	mSubRenderer
	Embedded renderer. More...

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

int	mCurrentVertexMarkerType
	The current type of editing marker. More...

bool	mForceRaster = false

QgsFeatureRequest::OrderBy	mOrderBy

bool	mOrderByEnabled = false

QgsPaintEffect *	mPaintEffect = nullptr

QString	mType

bool	mUsingSymbolLevels = false

Additional Inherited Members
Public Types inherited from QgsFeatureRenderer
enum	Capability { SymbolLevels = 1 , MoreSymbolsPerFeature = 1 << 2 , Filter = 1 << 3 , ScaleDependent = 1 << 4 }
	Used to specify details about a renderer. More...

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. More...

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

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

Detailed Description

QgsMergedFeatureRenderer is a polygon or line-only feature renderer used to renderer 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.

Since: QGIS 3.18

Definition at line 39 of file qgsmergedfeaturerenderer.h.

Member Enumeration Documentation

◆ GeometryOperation

enum QgsMergedFeatureRenderer::GeometryOperation

protected

Operations to apply to collected geometries prior to rendering.

Enumerator
Merge	Merge features (union/dissolve)
InvertOnly	Invert features only (polygons only)
MergeAndInvert	Merge and invert features (polygons only)

Definition at line 117 of file qgsmergedfeaturerenderer.h.

Constructor & Destructor Documentation

◆ QgsMergedFeatureRenderer() [1/3]

QgsMergedFeatureRenderer::QgsMergedFeatureRenderer ( QgsFeatureRenderer * embeddedRenderer )

Constructor for QgsMergedFeatureRenderer.

Parameters

embeddedRenderer optional embeddedRenderer. Ownership will be transferred.

Definition at line 33 of file qgsmergedfeaturerenderer.cpp.

◆ QgsMergedFeatureRenderer() [2/3]

QgsMergedFeatureRenderer::QgsMergedFeatureRenderer ( const QgsMergedFeatureRenderer & )

delete

Direct copies are forbidden. Use clone() instead.

◆ QgsMergedFeatureRenderer() [3/3]

QgsMergedFeatureRenderer::QgsMergedFeatureRenderer	(	const QString &	type,
		QgsFeatureRenderer *	embeddedRenderer
	)

protected

Constructor for QgsMergedFeatureRenderer.

Parameters

type	renderer ID string
embeddedRenderer	optional embeddedRenderer. Ownership will be transferred.

Definition at line 39 of file qgsmergedfeaturerenderer.cpp.

Member Function Documentation

◆ accept()

bool QgsMergedFeatureRenderer::accept ( QgsStyleEntityVisitorInterface * visitor ) const

overridevirtual

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

Returns true if the visitor should continue visiting other objects, or false if visiting should be canceled.

Since: QGIS 3.10

Reimplemented from QgsFeatureRenderer.

Definition at line 90 of file qgsmergedfeaturerenderer.cpp.

◆ capabilities()

QgsFeatureRenderer::Capabilities QgsMergedFeatureRenderer::capabilities ( )

overridevirtual

Returns details about internals of this renderer.

E.g. if you only want to deal with visible features:

if not renderer.capabilities().testFlag(QgsFeatureRenderer.Filter) or renderer.willRenderFeature(feature, context):
    deal_with_my_feature()
else:
    skip_the_curren_feature()

Reimplemented from QgsFeatureRenderer.

Definition at line 515 of file qgsmergedfeaturerenderer.cpp.

◆ checkLegendSymbolItem()

void QgsMergedFeatureRenderer::checkLegendSymbolItem	(	const QString &	key,
		bool	state = `true`
	)

overridevirtual

item in symbology was checked

Since: QGIS 2.5

Reimplemented from QgsFeatureRenderer.

Definition at line 82 of file qgsmergedfeaturerenderer.cpp.

◆ clone()

QgsMergedFeatureRenderer * QgsMergedFeatureRenderer::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 411 of file qgsmergedfeaturerenderer.cpp.

◆ convertFromRenderer()

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

static

Creates a QgsMergedFeatureRenderer by a conversion from an existing renderer.

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

Definition at line 556 of file qgsmergedfeaturerenderer.cpp.

◆ create()

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

static

Creates a renderer out of an XML, for loading.

Definition at line 426 of file qgsmergedfeaturerenderer.cpp.

◆ dump()

QString QgsMergedFeatureRenderer::dump ( ) const

overridevirtual

Returns debug information about this renderer.

Reimplemented from QgsFeatureRenderer.

Definition at line 402 of file qgsmergedfeaturerenderer.cpp.

◆ embeddedRenderer()

const QgsFeatureRenderer * QgsMergedFeatureRenderer::embeddedRenderer ( ) const

overridevirtual

Returns the current embedded renderer (subrenderer) for this feature renderer.

The base class implementation does not use subrenderers and will always return nullptr.

See also: setEmbeddedRenderer()

Since: QGIS 2.16

Reimplemented from QgsFeatureRenderer.

Definition at line 53 of file qgsmergedfeaturerenderer.cpp.

◆ filterNeedsGeometry()

bool QgsMergedFeatureRenderer::filterNeedsGeometry ( ) const

overridevirtual

Returns true if this renderer requires the geometry to apply the filter.

Reimplemented from QgsFeatureRenderer.

Definition at line 533 of file qgsmergedfeaturerenderer.cpp.

◆ legendKeysForFeature()

QSet< QString > QgsMergedFeatureRenderer::legendKeysForFeature	(	const QgsFeature &	feature,
		QgsRenderContext &	context
	)		const

overridevirtual

Returns legend keys matching a specified feature.

Since: QGIS 2.14

Reimplemented from QgsFeatureRenderer.

Definition at line 499 of file qgsmergedfeaturerenderer.cpp.

◆ legendSymbolItemChecked()

bool QgsMergedFeatureRenderer::legendSymbolItemChecked ( const QString & key )

overridevirtual

items of symbology items in legend is checked

Since: QGIS 2.5

Reimplemented from QgsFeatureRenderer.

Definition at line 74 of file qgsmergedfeaturerenderer.cpp.

◆ legendSymbolItems()

QgsLegendSymbolList QgsMergedFeatureRenderer::legendSymbolItems ( ) const

overridevirtual

Returns a list of symbology items for the legend.

Since: QGIS 2.6

Reimplemented from QgsFeatureRenderer.

Definition at line 538 of file qgsmergedfeaturerenderer.cpp.

◆ legendSymbolItemsCheckable()

bool QgsMergedFeatureRenderer::legendSymbolItemsCheckable ( ) const

overridevirtual

items of symbology items in legend should be checkable

Since: QGIS 2.5

Reimplemented from QgsFeatureRenderer.

Definition at line 66 of file qgsmergedfeaturerenderer.cpp.

◆ operator=()

QgsMergedFeatureRenderer& QgsMergedFeatureRenderer::operator= ( const QgsMergedFeatureRenderer & )

delete

Direct copies are forbidden. Use clone() instead.

◆ originalSymbolForFeature()

QgsSymbol * QgsMergedFeatureRenderer::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.

Since: QGIS 2.12

Reimplemented from QgsFeatureRenderer.

Definition at line 476 of file qgsmergedfeaturerenderer.cpp.

◆ originalSymbolsForFeature()

QgsSymbolList QgsMergedFeatureRenderer::originalSymbolsForFeature	(	const QgsFeature &	feature,
		QgsRenderContext &	context
	)		const

overridevirtual

Equivalent of originalSymbolsForFeature() call extended to support renderers that may use more symbols per feature - similar to symbolsForFeature()

Since: QGIS 2.12

Reimplemented from QgsFeatureRenderer.

Definition at line 492 of file qgsmergedfeaturerenderer.cpp.

◆ renderFeature()

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

overridevirtual

Renders a given feature.

This will here collect features. The actual rendering will be postponed to stopRender()

Parameters

feature	the feature to render
context	the rendering context
layer	the symbol layer to render, if that makes sense
selected	whether this feature has been selected (this will add decorations)
drawVertexMarker	whether this feature has vertex markers (in edit mode usually)

Returns: true if the rendering was OK

Reimplemented from QgsFeatureRenderer.

Definition at line 168 of file qgsmergedfeaturerenderer.cpp.

◆ save()

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

overridevirtual

store renderer info to XML element

Reimplemented from QgsFeatureRenderer.

Definition at line 439 of file qgsmergedfeaturerenderer.cpp.

◆ setEmbeddedRenderer()

void QgsMergedFeatureRenderer::setEmbeddedRenderer ( QgsFeatureRenderer * subRenderer )

overridevirtual

Sets an embedded renderer (subrenderer) for this feature renderer.

The base class implementation does nothing with subrenderers, but individual derived classes can use these to modify their behavior.

Parameters

subRenderer the embedded renderer. Ownership will be transferred.

See also: embeddedRenderer()

Since: QGIS 2.16

Reimplemented from QgsFeatureRenderer.

Definition at line 48 of file qgsmergedfeaturerenderer.cpp.

◆ setLegendSymbolItem()

void QgsMergedFeatureRenderer::setLegendSymbolItem	(	const QString &	key,
		QgsSymbol *	symbol
	)

overridevirtual

Sets the symbol to be used for a legend symbol item.

Parameters

key	rule key for legend symbol
symbol	new symbol for legend item. Ownership is transferred to renderer.

Since: QGIS 2.14

Reimplemented from QgsFeatureRenderer.

Definition at line 58 of file qgsmergedfeaturerenderer.cpp.

◆ startRender()

void QgsMergedFeatureRenderer::startRender	(	QgsRenderContext &	context,
		const QgsFields &	fields
	)

overridevirtual

Must be called when a new render cycle is started.

A call to startRender() must always be followed by a corresponding call to stopRender() after all features have been rendered.

Parameters

context	Additional information passed to the renderer about the job which will be rendered
fields	The fields available for rendering

See also: stopRender()

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.

Reimplemented from QgsFeatureRenderer.

Definition at line 98 of file qgsmergedfeaturerenderer.cpp.

◆ stopRender()

void QgsMergedFeatureRenderer::stopRender ( QgsRenderContext & context )

overridevirtual

The actual rendering will take place here.

Features collected during renderFeature() are rendered using the embedded feature renderer

Reimplemented from QgsFeatureRenderer.

Definition at line 265 of file qgsmergedfeaturerenderer.cpp.

◆ symbolForFeature()

QgsSymbol * QgsMergedFeatureRenderer::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

Since: QGIS 2.12

Implements QgsFeatureRenderer.

Definition at line 467 of file qgsmergedfeaturerenderer.cpp.

◆ symbols()

QgsSymbolList QgsMergedFeatureRenderer::symbols ( QgsRenderContext & context ) const

overridevirtual

Returns list of symbols used by the renderer.

Parameters

context render context

Since: QGIS 2.12

Reimplemented from QgsFeatureRenderer.

Definition at line 506 of file qgsmergedfeaturerenderer.cpp.

◆ symbolsForFeature()

QgsSymbolList QgsMergedFeatureRenderer::symbolsForFeature	(	const QgsFeature &	feature,
		QgsRenderContext &	context
	)		const

overridevirtual

Returns list of symbols used for rendering the feature.

For renderers that do not support MoreSymbolsPerFeature it is more efficient to use symbolForFeature()

Since: QGIS 2.12

Reimplemented from QgsFeatureRenderer.

Definition at line 483 of file qgsmergedfeaturerenderer.cpp.

◆ usedAttributes()

QSet< QString > QgsMergedFeatureRenderer::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 524 of file qgsmergedfeaturerenderer.cpp.

◆ willRenderFeature()

bool QgsMergedFeatureRenderer::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().

Since: QGIS 2.12

Reimplemented from QgsFeatureRenderer.

Definition at line 547 of file qgsmergedfeaturerenderer.cpp.

Member Data Documentation

◆ mOperation

GeometryOperation QgsMergedFeatureRenderer::mOperation = Merge

protected

Operation to apply to collected geometries.

Definition at line 125 of file qgsmergedfeaturerenderer.h.

◆ mSubRenderer

std::unique_ptr<QgsFeatureRenderer> QgsMergedFeatureRenderer::mSubRenderer

protected

Embedded renderer.

Definition at line 128 of file qgsmergedfeaturerenderer.h.

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

/build/qgis-3.20.0+99unstable/src/core/symbology/qgsmergedfeaturerenderer.h
/build/qgis-3.20.0+99unstable/src/core/symbology/qgsmergedfeaturerenderer.cpp

Public Member Functions

Static Public Member Functions

Protected Types

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

◆ GeometryOperation

Constructor & Destructor Documentation

◆ QgsMergedFeatureRenderer() [1/3]

◆ QgsMergedFeatureRenderer() [2/3]

◆ QgsMergedFeatureRenderer() [3/3]

Member Function Documentation

◆ accept()

◆ capabilities()

◆ checkLegendSymbolItem()

◆ clone()

◆ convertFromRenderer()

◆ create()

◆ dump()

◆ embeddedRenderer()

◆ filterNeedsGeometry()

◆ legendKeysForFeature()

◆ legendSymbolItemChecked()

◆ legendSymbolItems()

◆ legendSymbolItemsCheckable()

◆ operator=()

◆ originalSymbolForFeature()

◆ originalSymbolsForFeature()

◆ renderFeature()

◆ save()

◆ setEmbeddedRenderer()

◆ setLegendSymbolItem()

◆ startRender()

◆ stopRender()

◆ symbolForFeature()

◆ symbols()

◆ symbolsForFeature()

◆ usedAttributes()

◆ willRenderFeature()

Member Data Documentation

◆ mOperation

◆ mSubRenderer