QGIS API Documentation
3.0.2-Girona (307d082)
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The QgsLabelingEngine class provides map labeling functionality. More...
#include <qgslabelingengine.h>
Public Member Functions | |
QgsLabelingEngine () | |
Construct the labeling engine with default settings. More... | |
QgsLabelingEngine (const QgsLabelingEngine &rh)=delete | |
QgsLabelingEngine cannot be copied. More... | |
~QgsLabelingEngine () | |
Clean up everything (especially the registered providers) More... | |
void | addProvider (QgsAbstractLabelProvider *provider) |
Add provider of label features. Takes ownership of the provider. More... | |
const QgsLabelingEngineSettings & | engineSettings () const |
Get associated labeling engine settings. More... | |
const QgsMapSettings & | mapSettings () const |
Get associated map settings. More... | |
QgsLabelingEngine & | operator= (const QgsLabelingEngine &rh)=delete |
QgsLabelingEngine cannot be copied. More... | |
QList< QgsMapLayer *> | participatingLayers () const |
Returns a list of layers with providers in the engine. More... | |
void | removeProvider (QgsAbstractLabelProvider *provider) |
Remove provider if the provider's initialization failed. Provider instance is deleted. More... | |
QgsLabelingResults * | results () const |
For internal use by the providers. More... | |
void | run (QgsRenderContext &context) |
compute the labeling with given map settings and providers More... | |
void | setMapSettings (const QgsMapSettings &mapSettings) |
Associate map settings instance. More... | |
QgsLabelingResults * | takeResults () |
Return pointer to recently computed results and pass the ownership of results to the caller. More... | |
Protected Member Functions | |
void | processProvider (QgsAbstractLabelProvider *provider, QgsRenderContext &context, pal::Pal &p) |
Protected Attributes | |
QgsMapSettings | mMapSettings |
Associated map settings instance. More... | |
QList< QgsAbstractLabelProvider * > | mProviders |
List of providers (the are owned by the labeling engine) More... | |
std::unique_ptr< QgsLabelingResults > | mResults |
Resulting labeling layout. More... | |
QList< QgsAbstractLabelProvider * > | mSubProviders |
The QgsLabelingEngine class provides map labeling functionality.
The input for the engine is a list of label provider objects and map settings. Based on the input, the engine computes layout of labels for the given map view with no collisions between the labels. Drawing of resulting labels is done again by label providers.
The labeling engine is used for the map rendering in QgsMapRendererJob instances, individual map layer renderers may add label providers - for example, QgsVectorLayerRenderer may add text label provider and diagram provider (if labeling / diagrams were configured for such vector layer).
The labeling engine may also be used independently from map rendering loop:
Definition at line 170 of file qgslabelingengine.h.
QgsLabelingEngine::QgsLabelingEngine | ( | ) |
Construct the labeling engine with default settings.
Definition at line 74 of file qgslabelingengine.cpp.
QgsLabelingEngine::~QgsLabelingEngine | ( | ) |
Clean up everything (especially the registered providers)
Definition at line 78 of file qgslabelingengine.cpp.
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delete |
QgsLabelingEngine cannot be copied.
void QgsLabelingEngine::addProvider | ( | QgsAbstractLabelProvider * | provider | ) |
Add provider of label features. Takes ownership of the provider.
Definition at line 100 of file qgslabelingengine.cpp.
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Get associated labeling engine settings.
Definition at line 189 of file qgslabelingengine.h.
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Get associated map settings.
Definition at line 186 of file qgslabelingengine.h.
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delete |
QgsLabelingEngine cannot be copied.
QList< QgsMapLayer *> QgsLabelingEngine::participatingLayers | ( | ) | const |
Returns a list of layers with providers in the engine.
Definition at line 84 of file qgslabelingengine.cpp.
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protected |
Definition at line 115 of file qgslabelingengine.cpp.
void QgsLabelingEngine::removeProvider | ( | QgsAbstractLabelProvider * | provider | ) |
Remove provider if the provider's initialization failed. Provider instance is deleted.
Definition at line 106 of file qgslabelingengine.cpp.
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inline |
For internal use by the providers.
Definition at line 210 of file qgslabelingengine.h.
void QgsLabelingEngine::run | ( | QgsRenderContext & | context | ) |
compute the labeling with given map settings and providers
Definition at line 188 of file qgslabelingengine.cpp.
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Associate map settings instance.
Definition at line 184 of file qgslabelingengine.h.
QgsLabelingResults * QgsLabelingEngine::takeResults | ( | ) |
Return pointer to recently computed results and pass the ownership of results to the caller.
Definition at line 348 of file qgslabelingengine.cpp.
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Associated map settings instance.
Definition at line 217 of file qgslabelingengine.h.
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List of providers (the are owned by the labeling engine)
Definition at line 220 of file qgslabelingengine.h.
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Resulting labeling layout.
Definition at line 224 of file qgslabelingengine.h.
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Definition at line 221 of file qgslabelingengine.h.