A renderer which draws points as a live heatmap. More...

#include <qgsheatmaprenderer.h>

Inheritance diagram for QgsHeatmapRenderer:

Public Member Functions
	QgsHeatmapRenderer ()

	QgsHeatmapRenderer (const QgsHeatmapRenderer &)=delete
	Direct copies are forbidden. Use clone() instead.

	~QgsHeatmapRenderer () override

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

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

QgsColorRamp *	colorRamp () const
	Returns the color ramp used for shading the heatmap.

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

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

const QgsColorRampLegendNodeSettings &	legendSettings () const
	Returns the color ramp legend settings.

double	maximumValue () const
	Returns the maximum value used for shading the heatmap.

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

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

double	radius () const
	Returns the radius for the heatmap.

const QgsMapUnitScale &	radiusMapUnitScale () const
	Returns the map unit scale used for the heatmap's radius.

Qgis::RenderUnit	radiusUnit () const
	Returns the units used for the heatmap's radius.

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.

double	renderQuality () const
	Returns the render quality used for drawing the heatmap.

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

void	setColorRamp (QgsColorRamp *ramp)
	Sets the color ramp to use for shading the heatmap.

void	setLegendSettings (const QgsColorRampLegendNodeSettings &settings)
	Sets the color ramp legend settings.

void	setMaximumValue (const double value)
	Sets the maximum value used for shading the heatmap.

void	setRadius (const double radius)
	Sets the radius for the heatmap.

void	setRadiusMapUnitScale (const QgsMapUnitScale &scale)
	Sets the map unit scale used for the heatmap's radius.

void	setRadiusUnit (const Qgis::RenderUnit unit)
	Sets the units used for the heatmap's radius.

void	setRenderQuality (const int quality)
	Sets the render quality used for drawing the heatmap.

void	setWeightExpression (const QString &expression)
	Sets the expression used for weighting points when generating the heatmap.

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

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

QgsSymbolList	symbols (QgsRenderContext &context) const override

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

QString	weightExpression () const
	Returns the expression used for weighting points when generating the heatmap.

Public Member Functions inherited from QgsFeatureRenderer
virtual	~QgsFeatureRenderer ()

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.

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.

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.

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

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

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 QgsHeatmapRenderer *	convertFromRenderer (const QgsFeatureRenderer *renderer)

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

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

A renderer which draws points as a live heatmap.

Definition at line 34 of file qgsheatmaprenderer.h.

Constructor & Destructor Documentation

◆ QgsHeatmapRenderer() [1/2]

QgsHeatmapRenderer::QgsHeatmapRenderer ( )

Definition at line 31 of file qgsheatmaprenderer.cpp.

◆ ~QgsHeatmapRenderer()

QgsHeatmapRenderer::~QgsHeatmapRenderer ( )

override

Definition at line 39 of file qgsheatmaprenderer.cpp.

◆ QgsHeatmapRenderer() [2/2]

QgsHeatmapRenderer::QgsHeatmapRenderer ( const QgsHeatmapRenderer & )

delete

Direct copies are forbidden. Use clone() instead.

Member Function Documentation

◆ accept()

bool QgsHeatmapRenderer::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 405 of file qgsheatmaprenderer.cpp.

◆ clone()

QgsHeatmapRenderer * QgsHeatmapRenderer::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 286 of file qgsheatmaprenderer.cpp.

◆ colorRamp()

QgsColorRamp * QgsHeatmapRenderer::colorRamp ( ) const

inline

Returns the color ramp used for shading the heatmap.

Returns: color ramp for heatmap

See also: setColorRamp

Definition at line 75 of file qgsheatmaprenderer.h.

◆ convertFromRenderer()

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

static

Definition at line 391 of file qgsheatmaprenderer.cpp.

◆ create()

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

static

Creates a new heatmap renderer instance from XML.

Definition at line 316 of file qgsheatmaprenderer.cpp.

◆ createLegendNodes()

QList< QgsLayerTreeModelLegendNode * > QgsHeatmapRenderer::createLegendNodes ( QgsLayerTreeLayer * nodeLayer ) const

overridevirtual

Returns a list of legend nodes to be used for the legend for the renderer.

Ownership is transferred to the caller.

The default implementation creates a legend node for each symbol item returned by legendSymbolItems()

See also: legendSymbolItems()

Since: QGIS 3.38

Reimplemented from QgsFeatureRenderer.

Definition at line 416 of file qgsheatmaprenderer.cpp.

◆ dump()

QString QgsHeatmapRenderer::dump ( ) const

overridevirtual

Returns debug information about this renderer.

Reimplemented from QgsFeatureRenderer.

Definition at line 281 of file qgsheatmaprenderer.cpp.

◆ legendSettings()

const QgsColorRampLegendNodeSettings & QgsHeatmapRenderer::legendSettings ( ) const

inline

Returns the color ramp legend settings.

See also: setLegendSettings()

Since: QGIS 3.38

Definition at line 90 of file qgsheatmaprenderer.h.

◆ maximumValue()

double QgsHeatmapRenderer::maximumValue ( ) const

inline

Returns the maximum value used for shading the heatmap.

Returns: maximum value for heatmap shading. If 0, then maximum value will be automatically calculated.

See also: setMaximumValue

Definition at line 160 of file qgsheatmaprenderer.h.

◆ modifyRequestExtent()

void QgsHeatmapRenderer::modifyRequestExtent	(	QgsRectangle &	extent,
		QgsRenderContext &	context
	)

overridevirtual

Allows for a renderer to modify the extent of a feature request prior to rendering.

Parameters

extent	reference to request's filter extent. Modify extent to change the extent of feature request
context	render context

Reimplemented from QgsFeatureRenderer.

Definition at line 305 of file qgsheatmaprenderer.cpp.

◆ operator=()

QgsHeatmapRenderer & QgsHeatmapRenderer::operator= ( const QgsHeatmapRenderer & )

delete

Direct copies are forbidden. Use clone() instead.

◆ radius()

double QgsHeatmapRenderer::radius ( ) const

inline

Returns the radius for the heatmap.

Returns: heatmap radius

See also: setRadius; radiusUnit; radiusMapUnitScale

Definition at line 107 of file qgsheatmaprenderer.h.

◆ radiusMapUnitScale()

const QgsMapUnitScale & QgsHeatmapRenderer::radiusMapUnitScale ( ) const

inline

Returns the map unit scale used for the heatmap's radius.

Returns: map unit scale for heatmap's radius

See also: radius; radiusUnit; setRadiusMapUnitScale

Definition at line 143 of file qgsheatmaprenderer.h.

◆ radiusUnit()

Qgis::RenderUnit QgsHeatmapRenderer::radiusUnit ( ) const

inline

Returns the units used for the heatmap's radius.

Returns: units for heatmap radius

See also: radius; setRadiusUnit; radiusMapUnitScale

Definition at line 125 of file qgsheatmaprenderer.h.

◆ renderFeature()

bool QgsHeatmapRenderer::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 98 of file qgsheatmaprenderer.cpp.

◆ renderQuality()

double QgsHeatmapRenderer::renderQuality ( ) const

inline

Returns the render quality used for drawing the heatmap.

Returns: render quality. A value of 1 indicates maximum quality, and increasing the value will result in faster drawing but lower quality rendering.

See also: setRenderQuality

Definition at line 176 of file qgsheatmaprenderer.h.

◆ save()

QDomElement QgsHeatmapRenderer::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 340 of file qgsheatmaprenderer.cpp.

◆ setColorRamp()

void QgsHeatmapRenderer::setColorRamp ( QgsColorRamp * ramp )

Sets the color ramp to use for shading the heatmap.

Parameters

ramp	color ramp for heatmap. Ownership of ramp is transferred to the renderer.

See also: colorRamp

Definition at line 428 of file qgsheatmaprenderer.cpp.

◆ setLegendSettings()

void QgsHeatmapRenderer::setLegendSettings ( const QgsColorRampLegendNodeSettings & settings )

Sets the color ramp legend settings.

See also: legendSettings()

Since: QGIS 3.38

Definition at line 434 of file qgsheatmaprenderer.cpp.

◆ setMaximumValue()

void QgsHeatmapRenderer::setMaximumValue ( const double value )

inline

Sets the maximum value used for shading the heatmap.

Parameters

value maximum value for heatmap shading. Set to 0 for automatic calculation of maximum value.

See also: maximumValue

Definition at line 168 of file qgsheatmaprenderer.h.

◆ setRadius()

void QgsHeatmapRenderer::setRadius ( const double radius )

inline

Sets the radius for the heatmap.

Parameters

radius heatmap radius

See also: radius; setRadiusUnit; setRadiusMapUnitScale

Definition at line 116 of file qgsheatmaprenderer.h.

◆ setRadiusMapUnitScale()

void QgsHeatmapRenderer::setRadiusMapUnitScale ( const QgsMapUnitScale & scale )

inline

Sets the map unit scale used for the heatmap's radius.

Parameters

scale map unit scale for heatmap's radius

See also: setRadius; setRadiusUnit; radiusMapUnitScale

Definition at line 152 of file qgsheatmaprenderer.h.

◆ setRadiusUnit()

void QgsHeatmapRenderer::setRadiusUnit ( const Qgis::RenderUnit unit )

inline

Sets the units used for the heatmap's radius.

Parameters

unit	units for heatmap radius

See also: radiusUnit; setRadius; radiusMapUnitScale

Definition at line 134 of file qgsheatmaprenderer.h.

◆ setRenderQuality()

void QgsHeatmapRenderer::setRenderQuality ( const int quality )

inline

Sets the render quality used for drawing the heatmap.

Parameters

quality render quality. A value of 1 indicates maximum quality, and increasing the value will result in faster drawing but lower quality rendering.

See also: renderQuality

Definition at line 184 of file qgsheatmaprenderer.h.

◆ setWeightExpression()

void QgsHeatmapRenderer::setWeightExpression ( const QString & expression )

inline

Sets the expression used for weighting points when generating the heatmap.

Parameters

expression point weight expression. If set to empty, all points are equally weighted.

See also: weightExpression

Definition at line 198 of file qgsheatmaprenderer.h.

◆ startRender()

void QgsHeatmapRenderer::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 54 of file qgsheatmaprenderer.cpp.

◆ stopRender()

void QgsHeatmapRenderer::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 225 of file qgsheatmaprenderer.cpp.

◆ symbolForFeature()

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

overridevirtual

Note: symbolForFeature2 in Python bindings

Implements QgsFeatureRenderer.

Definition at line 363 of file qgsheatmaprenderer.cpp.

◆ symbols()

QgsSymbolList QgsHeatmapRenderer::symbols ( QgsRenderContext & context ) const

overridevirtual

Note: symbol2 in Python bindings

Reimplemented from QgsFeatureRenderer.

Definition at line 369 of file qgsheatmaprenderer.cpp.

◆ usedAttributes()

QSet< QString > QgsHeatmapRenderer::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 374 of file qgsheatmaprenderer.cpp.

◆ weightExpression()

QString QgsHeatmapRenderer::weightExpression ( ) const

inline

Returns the expression used for weighting points when generating the heatmap.

Returns: point weight expression. If empty, all points are equally weighted.

See also: setWeightExpression

Definition at line 191 of file qgsheatmaprenderer.h.

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

/home/fischer/src/qgis-3.38/src/core/symbology/qgsheatmaprenderer.h
/home/fischer/src/qgis-3.38/src/core/symbology/qgsheatmaprenderer.cpp

Public Member Functions

Static Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QgsHeatmapRenderer() [1/2]

◆ ~QgsHeatmapRenderer()

◆ QgsHeatmapRenderer() [2/2]

Member Function Documentation

◆ accept()

◆ clone()

◆ colorRamp()

◆ convertFromRenderer()

◆ create()

◆ createLegendNodes()

◆ dump()

◆ legendSettings()

◆ maximumValue()

◆ modifyRequestExtent()

◆ operator=()

◆ radius()

◆ radiusMapUnitScale()

◆ radiusUnit()

◆ renderFeature()

◆ renderQuality()

◆ save()

◆ setColorRamp()

◆ setLegendSettings()

◆ setMaximumValue()

◆ setRadius()

◆ setRadiusMapUnitScale()

◆ setRadiusUnit()

◆ setRenderQuality()

◆ setWeightExpression()

◆ startRender()

◆ stopRender()

◆ symbolForFeature()

◆ symbols()

◆ usedAttributes()

◆ weightExpression()