QGIS API Documentation 3.41.0-Master (181b2f43d8e)
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Public Member Functions | Static Public Member Functions | List of all members
QgsNullSymbolRenderer Class Reference

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:
Inheritance graph
[legend]

Public Member Functions

 QgsNullSymbolRenderer ()
 
 ~QgsNullSymbolRenderer ()
 
QgsFeatureRendererclone () const override
 Create a deep copy of this renderer.
 
QString dump () const override
 Returns debug information about this renderer.
 
QgsSymboloriginalSymbolForFeature (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.
 
QgsSymbolsymbolForFeature (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.
 
QgsPropertyCollectiondataDefinedProperties ()
 Returns a reference to the renderer's property collection, used for data defined overrides.
 
const QgsPropertyCollectiondataDefinedProperties () const
 Returns a reference to the renderer's property collection, used for data defined overrides.
 
virtual const QgsFeatureRendererembeddedRenderer () 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.
 
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()
 
QgsPaintEffectpaintEffect () 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 QgsNullSymbolRendererconvertFromRenderer (const QgsFeatureRenderer *renderer)
 Creates a QgsNullSymbolRenderer from an existing renderer.
 
static QgsFeatureRenderercreate (QDomElement &element, const QgsReadWriteContext &context)
 Creates a null renderer from XML element.
 
- Static Public Member Functions inherited from QgsFeatureRenderer
static QgsFeatureRendererdefaultRenderer (Qgis::GeometryType geomType)
 Returns a new renderer - used by default in vector layers.
 
static QgsFeatureRendererload (QDomElement &symbologyElem, const QgsReadWriteContext &context)
 create a renderer from XML element
 
static QgsFeatureRendererloadSld (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 QgsPropertiesDefinitionpropertyDefinitions ()
 Returns the symbol property definitions.
 

Additional Inherited Members

- Public Types inherited from QgsFeatureRenderer
typedef QFlags< CapabilityCapabilities
 
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
 
QgsPaintEffectmPaintEffect = 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
rendererrenderer 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
elementDOM element
contextreading 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
featurefeature
contextrender 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
contextrender 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: