QGIS API Documentation  3.23.0-Master (22c16f2067)
Classes | Public Member Functions | Static Public Member Functions | Protected Types | Protected Member Functions | Protected Attributes | List of all members
QgsMergedFeatureRenderer Class Reference

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:
Inheritance graph
[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...
 
QgsMergedFeatureRendererclone () const override
 Create a deep copy of this renderer. More...
 
QString dump () const override
 Returns debug information about this renderer. More...
 
const QgsFeatureRendererembeddedRenderer () 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...
 
QgsMergedFeatureRendereroperator= (const QgsMergedFeatureRenderer &)=delete
 Direct copies are forbidden. Use clone() instead. More...
 
QgsSymboloriginalSymbolForFeature (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
 Stores renderer properties to an 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...
 
QgsSymbolsymbolForFeature (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 ()
 
void copyRendererData (QgsFeatureRenderer *destRenderer) const
 Clones generic renderer data to another renderer. More...
 
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...
 
QgsPaintEffectpaintEffect () const
 Returns the current paint effect for the renderer. More...
 
double referenceScale () const
 Returns the symbology reference scale. 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 setReferenceScale (double scale)
 Sets the symbology reference scale. More...
 
void setUsingSymbolLevels (bool usingSymbolLevels)
 
void setVertexMarkerAppearance (Qgis::VertexMarkerType 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 QgsMergedFeatureRendererconvertFromRenderer (const QgsFeatureRenderer *renderer)
 Creates a QgsMergedFeatureRenderer by a conversion from an existing renderer. More...
 
static QgsFeatureRenderercreate (QDomElement &element, const QgsReadWriteContext &context)
 Creates a renderer out of an XML, for loading. More...
 
- Static Public Member Functions inherited from QgsFeatureRenderer
static QgsFeatureRendererdefaultRenderer (QgsWkbTypes::GeometryType geomType)
 Returns a new renderer - used by default in vector layers. More...
 
static QgsFeatureRendererload (QDomElement &symbologyElem, const QgsReadWriteContext &context)
 create a renderer from XML element More...
 
static QgsFeatureRendererloadSld (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 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...
 
void saveRendererData (QDomDocument &doc, QDomElement &element, const QgsReadWriteContext &context)
 Saves generic renderer data into the specified element. More...
 

Protected Attributes

GeometryOperation mOperation = Merge
 Operation to apply to collected geometries. More...
 
std::unique_ptr< QgsFeatureRenderermSubRenderer
 Embedded renderer. More...
 
- Protected Attributes inherited from QgsFeatureRenderer
double mCurrentVertexMarkerSize = 2
 The current size of editing marker. More...
 
Qgis::VertexMarkerType mCurrentVertexMarkerType = Qgis::VertexMarkerType::Cross
 The current type of editing marker. More...
 
bool mForceRaster = false
 
QgsFeatureRequest::OrderBy mOrderBy
 
bool mOrderByEnabled = false
 
QgsPaintEffectmPaintEffect = nullptr
 
double mReferenceScale = -1.0
 
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 40 of file qgsmergedfeaturerenderer.h.

Member Enumeration Documentation

◆ GeometryOperation

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 118 of file qgsmergedfeaturerenderer.h.

Constructor & Destructor Documentation

◆ QgsMergedFeatureRenderer() [1/3]

QgsMergedFeatureRenderer::QgsMergedFeatureRenderer ( QgsFeatureRenderer embeddedRenderer)

Constructor for QgsMergedFeatureRenderer.

Parameters
embeddedRendereroptional 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
typerenderer ID string
embeddedRendereroptional 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 505 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 546 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 523 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 489 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 528 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 466 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 482 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
featurethe feature to render
contextthe rendering context
layerthe symbol layer to render, if that makes sense
selectedwhether this feature has been selected (this will add decorations)
drawVertexMarkerwhether 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

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 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
subRendererthe 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
keyrule key for legend symbol
symbolnew 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
contextAdditional information passed to the renderer about the job which will be rendered
fieldsThe 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
featurefeature
contextrender context
Returns
returns pointer to symbol or 0 if symbol was not found
Since
QGIS 2.12

Implements QgsFeatureRenderer.

Definition at line 457 of file qgsmergedfeaturerenderer.cpp.

◆ symbols()

QgsSymbolList QgsMergedFeatureRenderer::symbols ( QgsRenderContext context) const
overridevirtual

Returns list of symbols used by the renderer.

Parameters
contextrender context
Since
QGIS 2.12

Reimplemented from QgsFeatureRenderer.

Definition at line 496 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 473 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 514 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 537 of file qgsmergedfeaturerenderer.cpp.

Member Data Documentation

◆ mOperation

GeometryOperation QgsMergedFeatureRenderer::mOperation = Merge
protected

Operation to apply to collected geometries.

Definition at line 126 of file qgsmergedfeaturerenderer.h.

◆ mSubRenderer

std::unique_ptr<QgsFeatureRenderer> QgsMergedFeatureRenderer::mSubRenderer
protected

Embedded renderer.

Definition at line 129 of file qgsmergedfeaturerenderer.h.


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