QGIS API Documentation 3.37.0-Master (c2d15952569)
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qgsvectorlayercache.h
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1/***************************************************************************
2 qgsvectorlayercache.h
3 Cache features of a vector layer
4 -------------------
5 begin : January 2013
6 copyright : (C) Matthias Kuhn
7 email : matthias at opengis dot ch
8
9 ***************************************************************************
10 * *
11 * This program is free software; you can redistribute it and/or modify *
12 * it under the terms of the GNU General Public License as published by *
13 * the Free Software Foundation; either version 2 of the License, or *
14 * (at your option) any later version. *
15 * *
16 ***************************************************************************/
17
18
19#ifndef QgsVectorLayerCache_H
20#define QgsVectorLayerCache_H
21
22#include "qgis_core.h"
23#include "qgis_sip.h"
24#include "qgsfield.h"
25#include "qgsfeaturerequest.h"
26#include "qgsfeatureiterator.h"
27#include <unordered_set>
28#include <deque>
29#include <QCache>
30
31class QgsVectorLayer;
32class QgsFeature;
35
46class CORE_EXPORT QgsVectorLayerCache : public QObject
47{
48 Q_OBJECT
49
50 private:
51
57 class CORE_EXPORT QgsCachedFeature
58 {
59 public:
60
68 QgsCachedFeature( const QgsFeature &feat, QgsVectorLayerCache *vlCache, bool allAttributesFetched )
69 : mCache( vlCache )
70 , mAllAttributesFetched( allAttributesFetched )
71 {
72 mFeature = new QgsFeature( feat );
73 }
74
75 ~QgsCachedFeature()
76 {
77 // That's the reason we need this wrapper:
78 // Inform the cache that this feature has been removed
79 mCache->featureRemoved( mFeature->id() );
80 delete mFeature;
81 }
82
83 inline const QgsFeature *feature() { return mFeature; }
84
85 bool allAttributesFetched() const;
86
87 private:
88 QgsFeature *mFeature = nullptr;
89 QgsVectorLayerCache *mCache = nullptr;
90 bool mAllAttributesFetched = true;
91
92 friend class QgsVectorLayerCache;
93 Q_DISABLE_COPY( QgsCachedFeature )
94 };
95
96 public:
97 QgsVectorLayerCache( QgsVectorLayer *layer, int cacheSize, QObject *parent SIP_TRANSFERTHIS = nullptr );
98 ~QgsVectorLayerCache() override;
99
106 void setCacheSize( int cacheSize );
107
115 int cacheSize();
116
123 void setCacheGeometry( bool cacheGeometry );
124
129 bool cacheGeometry() const { return mCacheGeometry; }
130
137 void setCacheSubsetOfAttributes( const QgsAttributeList &attributes );
138
146 QgsAttributeList cacheSubsetOfAttributes( ) const;
147
154 void setCacheAddedAttributes( bool cacheAddedAttributes );
155
169 void setFullCache( bool fullCache );
170
177 bool hasFullCache() const { return mFullCache; }
178
187 void addCacheIndex( QgsAbstractCacheIndex *cacheIndex SIP_TRANSFER );
188
198 QgsFeatureIterator getFeatures( const QgsFeatureRequest &featureRequest = QgsFeatureRequest() );
199
203 inline QgsFeatureIterator getFeatures( const QString &expression )
204 {
205 return getFeatures( QgsFeatureRequest( expression ) );
206 }
207
213 {
214 QgsFeature feature;
215 getFeatures( QgsFeatureRequest( fid ) ).nextFeature( feature );
216 return feature;
217 }
218
223 {
224 return getFeatures( QgsFeatureRequest( fids ) );
225 }
226
230 inline QgsFeatureIterator getFeatures( const QgsRectangle &rectangle )
231 {
232 return getFeatures( QgsFeatureRequest( rectangle ) );
233 }
234
241 bool isFidCached( QgsFeatureId fid ) const;
242
247 QgsFeatureIds cachedFeatureIds() const;
248
256 bool featureAtId( QgsFeatureId featureId, QgsFeature &feature, bool skipCache = false );
257
271 bool featureAtIdWithAllAttributes( QgsFeatureId featureId, QgsFeature &feature, bool skipCache = false );
272
278 bool removeCachedFeature( QgsFeatureId fid );
279
283 QgsVectorLayer *layer();
284
288 QgsCoordinateReferenceSystem sourceCrs() const;
289
293 QgsFields fields() const;
294
298 Qgis::WkbType wkbType() const;
299
300#ifdef SIP_RUN
301
306 int __len__() const;
307 % MethodCode
308 sipRes = sipCpp->featureCount();
309 % End
310
312 int __bool__() const;
313 % MethodCode
314 sipRes = true;
315 % End
316#endif
317
322 long long featureCount() const;
323
324 protected:
325
334 void requestCompleted( const QgsFeatureRequest &featureRequest, const QgsFeatureIds &fids );
335
343 void featureRemoved( QgsFeatureId fid );
344
355 bool checkInformationCovered( const QgsFeatureRequest &featureRequest );
356
357
358 signals:
359
369 void progress( int i, bool &cancel ) SIP_SKIP;
370
374 void finished();
375
382
387 void attributeValueChanged( QgsFeatureId fid, int field, const QVariant &value );
388
397
404
405 private slots:
406 void onAttributeValueChanged( QgsFeatureId fid, int field, const QVariant &value );
407 void onJoinAttributeValueChanged( QgsFeatureId fid, int field, const QVariant &value );
408 void featureDeleted( QgsFeatureId fid );
409 void onFeatureAdded( QgsFeatureId fid );
410 void attributeAdded( int field );
411 void attributeDeleted( int field );
412 void geometryChanged( QgsFeatureId fid, const QgsGeometry &geom );
413 void layerDeleted();
414 void invalidate();
415
416 private:
417
418 void connectJoinedLayers() const;
419
420 inline void cacheFeature( QgsFeature &feat, bool allAttributesFetched )
421 {
422 QgsCachedFeature *cachedFeature = new QgsCachedFeature( feat, this, allAttributesFetched );
423 mCache.insert( feat.id(), cachedFeature );
424 if ( mCacheUnorderedKeys.find( feat.id() ) == mCacheUnorderedKeys.end() )
425 {
426 mCacheUnorderedKeys.insert( feat.id() );
427 mCacheOrderedKeys.emplace_back( feat.id() );
428 }
429 }
430
431 QgsVectorLayer *mLayer = nullptr;
432 QCache< QgsFeatureId, QgsCachedFeature > mCache;
433
434 // we need two containers here. One is used for efficient tracking of the IDs which have been added to the cache, the other
435 // is used to store the order of the incoming feature ids, so that we can correctly iterate through features in the original order.
436 // the ordered list alone is far too slow to handle this -- searching for existing items in a list is magnitudes slower than the unordered_set
437 std::unordered_set< QgsFeatureId > mCacheUnorderedKeys;
438 std::deque< QgsFeatureId > mCacheOrderedKeys;
439
440 bool mCacheGeometry = true;
441 bool mFullCache = false;
442 QList<QgsAbstractCacheIndex *> mCacheIndices;
443
444 QgsAttributeList mCachedAttributes;
445
448 friend class QgsCachedFeature;
449
458 bool canUseCacheForRequest( const QgsFeatureRequest &featureRequest, QgsFeatureIterator &it );
459
460 friend class TestVectorLayerCache;
461};
462#endif // QgsVectorLayerCache_H
WkbType
The WKB type describes the number of dimensions a geometry has.
Definition qgis.h:182
Abstract base class for cache indices.
Delivers features from the cache.
Uses another iterator as backend and writes features to the cache.
This class represents a coordinate reference system (CRS).
Wrapper for iterator of features from vector data provider or vector layer.
This class wraps a request for features to a vector layer (or directly its vector data provider).
The feature class encapsulates a single feature including its unique ID, geometry and a list of field...
Definition qgsfeature.h:56
QgsFeatureId id
Definition qgsfeature.h:64
Container of fields for a vector layer.
Definition qgsfields.h:45
A geometry is the spatial representation of a feature.
A rectangle specified with double values.
This class caches features of a given QgsVectorLayer.
bool hasFullCache() const
Returns true if the cache is complete, ie it contains all features.
QgsFeatureIterator getFeatures(const QString &expression)
Query the layer for features matching a given expression.
void finished()
When filling the cache, this signal gets emitted once the cache is fully initialized.
void invalidated()
The cache has been invalidated and cleared.
QgsFeatureIterator getFeatures(const QgsRectangle &rectangle)
Query the layer for the features which intersect the specified rectangle.
void featureAdded(QgsFeatureId fid)
Emitted when a new feature has been added to the layer and this cache.
QgsFeatureIterator getFeatures(const QgsFeatureIds &fids)
Query the layer for the features with the given ids.
QgsFeature getFeature(QgsFeatureId fid)
Query the layer for the feature with the given id.
void cachedLayerDeleted()
Is emitted when the cached layer is deleted.
void attributeValueChanged(QgsFeatureId fid, int field, const QVariant &value)
Emitted when an attribute is changed.
void progress(int i, bool &cancel)
When filling the cache, this signal gets emitted periodically to notify about the progress and to be ...
bool cacheGeometry() const
Returns true if the cache will fetch and cache feature geometries.
Represents a vector layer which manages a vector based data sets.
#define SIP_TRANSFERTHIS
Definition qgis_sip.h:53
#define SIP_SKIP
Definition qgis_sip.h:126
#define SIP_TRANSFER
Definition qgis_sip.h:36
QSet< QgsFeatureId > QgsFeatureIds
qint64 QgsFeatureId
64 bit feature ids negative numbers are used for uncommitted/newly added features
QList< int > QgsAttributeList
Definition qgsfield.h:27