QgsAbstractCacheIndex Class Reference

Abstract base class for cache indices. More...

#include <qgscacheindex.h>

Inheritance diagram for QgsAbstractCacheIndex:

Public Member Functions
	QgsAbstractCacheIndex ()=default
	Constructor for QgsAbstractCacheIndex. More...
virtual	~QgsAbstractCacheIndex ()=default
virtual void	flush ()=0
	Sometimes, the whole cache changes its state and its easier to just withdraw everything. More...
virtual void	flushFeature (QgsFeatureId fid)=0
	Is called whenever a feature is removed from the cache. More...
virtual bool	getCacheIterator (QgsFeatureIterator &featureIterator, const QgsFeatureRequest &featureRequest)=0
	Is called when a feature request is issued on a cached layer. More...
virtual void	requestCompleted (const QgsFeatureRequest &featureRequest, const QgsFeatureIds &fids)
	Implement this method to update the the indices, in case you need information contained by the request to properly index. More...

Detailed Description

Abstract base class for cache indices.

Definition at line 31 of file qgscacheindex.h.

Constructor & Destructor Documentation

QgsAbstractCacheIndex()

QgsAbstractCacheIndex::QgsAbstractCacheIndex ( )

default

Constructor for QgsAbstractCacheIndex.

~QgsAbstractCacheIndex()

virtual QgsAbstractCacheIndex::~QgsAbstractCacheIndex ( )

virtualdefault

Member Function Documentation

flush()

virtual void QgsAbstractCacheIndex::flush ( )

pure virtual

Sometimes, the whole cache changes its state and its easier to just withdraw everything.

In this case, this method is issued. Be sure to clear all cache information in here.

Implemented in QgsCacheIndexFeatureId.

flushFeature()

virtual void QgsAbstractCacheIndex::flushFeature ( QgsFeatureId  fid )

pure virtual

Is called whenever a feature is removed from the cache.

You should update your indexes so they become invalid in case this feature was required to successfully answer a request.

Implemented in QgsCacheIndexFeatureId.

getCacheIterator()

virtual bool QgsAbstractCacheIndex::getCacheIterator ( QgsFeatureIterator &  featureIterator, const QgsFeatureRequest &  featureRequest  )

pure virtual

Is called when a feature request is issued on a cached layer.

If this cache index is able to completely answer the feature request, it will return true and set the iterator to a valid iterator over the cached features. If it is not able it will return false.

Parameters

featureIterator	A reference to a QgsFeatureIterator. A valid featureIterator will be assigned in case this index is able to answer the request and the return value is true.
featureRequest	The feature request, for which this index is queried.

Returns

true, if this index holds the information to answer the request.

Implemented in QgsCacheIndexFeatureId.

requestCompleted()

void QgsAbstractCacheIndex::requestCompleted ( const QgsFeatureRequest &  featureRequest, const QgsFeatureIds &  fids  )

virtual

Implement this method to update the the indices, in case you need information contained by the request to properly index.

(E.g. spatial index) Does nothing by default

Parameters

featureRequest	The feature request that was answered
fids	The feature ids that have been returned

Reimplemented in QgsCacheIndexFeatureId.

Definition at line 19 of file qgscacheindex.cpp.

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

• /build/qgis-3.16.0+99unstable/src/core/qgscacheindex.h
• /build/qgis-3.16.0+99unstable/src/core/qgscacheindex.cpp