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       1                 :            : /***************************************************************************
       2                 :            :  *  qgsfeaturepool.h                                                       *
       3                 :            :  *  -------------------                                                    *
       4                 :            :  *  copyright            : (C) 2014 by Sandro Mani / Sourcepole AG         *
       5                 :            :  *  email                : smani@sourcepole.ch                             *
       6                 :            :  ***************************************************************************/
       7                 :            : 
       8                 :            : /***************************************************************************
       9                 :            :  *                                                                         *
      10                 :            :  *   This program is free software; you can redistribute it and/or modify  *
      11                 :            :  *   it under the terms of the GNU General Public License as published by  *
      12                 :            :  *   the Free Software Foundation; either version 2 of the License, or     *
      13                 :            :  *   (at your option) any later version.                                   *
      14                 :            :  *                                                                         *
      15                 :            :  ***************************************************************************/
      16                 :            : 
      17                 :            : #ifndef QGS_FEATUREPOOL_H
      18                 :            : #define QGS_FEATUREPOOL_H
      19                 :            : 
      20                 :            : #include <QCache>
      21                 :            : #include <QMutex>
      22                 :            : #include <QPointer>
      23                 :            : 
      24                 :            : #include "qgis_analysis.h"
      25                 :            : #include "qgsfeature.h"
      26                 :            : #include "qgsspatialindex.h"
      27                 :            : #include "qgsfeaturesink.h"
      28                 :            : #include "qgsvectorlayerfeatureiterator.h"
      29                 :            : 
      30                 :            : /**
      31                 :            :  * \ingroup analysis
      32                 :            :  * \brief A feature pool is based on a vector layer and caches features.
      33                 :            :  *
      34                 :            :  * \note This class is a technology preview and unstable API.
      35                 :            :  * \since QGIS 3.4
      36                 :            :  */
      37                 :            : class ANALYSIS_EXPORT QgsFeaturePool : public QgsFeatureSink SIP_ABSTRACT
      38                 :            : {
      39                 :            : 
      40                 :            :   public:
      41                 :            : 
      42                 :            :     /**
      43                 :            :      * Creates a new feature pool for \a layer.
      44                 :            :      */
      45                 :            :     QgsFeaturePool( QgsVectorLayer *layer );
      46                 :         61 :     virtual ~QgsFeaturePool() = default;
      47                 :            : 
      48                 :            :     /**
      49                 :            :      * Retrieves the feature with the specified \a id into \a feature.
      50                 :            :      * It will be retrieved from the cache or from the underlying feature source if unavailable.
      51                 :            :      * If the feature is neither available from the cache nor from the source it will return FALSE.
      52                 :            :      */
      53                 :            :     bool getFeature( QgsFeatureId id, QgsFeature &feature );
      54                 :            : 
      55                 :            :     /**
      56                 :            :      * Gets features for the provided \a request. No features will be fetched
      57                 :            :      * from the cache and the request is sent directly to the underlying feature source.
      58                 :            :      * Results of the request are cached in the pool and the ids of all the features
      59                 :            :      * are returned. This is used to warm the cache for a particular area of interest
      60                 :            :      * (bounding box) or other set of features.
      61                 :            :      * This will get a new feature source from the source vector layer.
      62                 :            :      * This needs to be called from the main thread.
      63                 :            :      * If \a feedback is specified, the call may return if the feedback is canceled.
      64                 :            :      */
      65                 :            :     QgsFeatureIds getFeatures( const QgsFeatureRequest &request, QgsFeedback *feedback = nullptr ) SIP_SKIP;
      66                 :            : 
      67                 :            :     /**
      68                 :            :      * Updates a feature in this pool.
      69                 :            :      * Implementations will update the feature on the layer or on the data provider.
      70                 :            :      */
      71                 :            :     virtual void updateFeature( QgsFeature &feature ) = 0;
      72                 :            : 
      73                 :            :     /**
      74                 :            :      * Removes a feature from this pool.
      75                 :            :      * Implementations will remove the feature from the layer or from the data provider.
      76                 :            :      */
      77                 :            :     virtual void deleteFeature( QgsFeatureId fid ) = 0;
      78                 :            : 
      79                 :            :     /**
      80                 :            :      * Returns the complete set of feature ids in this pool.
      81                 :            :      * Note that this concerns the features governed by this pool, which are not necessarily all cached.
      82                 :            :      *
      83                 :            :      * \note not available in Python bindings
      84                 :            :      */
      85                 :            :     QgsFeatureIds allFeatureIds() const SIP_SKIP;
      86                 :            : 
      87                 :            :     /**
      88                 :            :      * Gets all feature ids in the bounding box \a rect. It will use a spatial index to
      89                 :            :      * determine the ids.
      90                 :            :      *
      91                 :            :      * \note not available in Python bindings
      92                 :            :      */
      93                 :            :     QgsFeatureIds getIntersects( const QgsRectangle &rect ) const SIP_SKIP;
      94                 :            : 
      95                 :            :     /**
      96                 :            :      * Gets a pointer to the underlying layer.
      97                 :            :      * May return a ``NULLPTR`` if the layer has been deleted.
      98                 :            :      * This must only be called from the main thread.
      99                 :            :      */
     100                 :            :     QgsVectorLayer *layer() const;
     101                 :            : 
     102                 :            :     /**
     103                 :            :      * Gets a QPointer to the underlying layer.
     104                 :            :      * Note that access to any methods of the object
     105                 :            :      * will need to be done on the main thread and
     106                 :            :      * the pointer will need to be checked for validity
     107                 :            :      * before usage.
     108                 :            :      *
     109                 :            :      * \note not available in Python bindings
     110                 :            :      */
     111                 :            :     QPointer<QgsVectorLayer> layerPtr() const SIP_SKIP;
     112                 :            : 
     113                 :            :     /**
     114                 :            :      * The layer id of the layer.
     115                 :            :      */
     116                 :            :     QString layerId() const;
     117                 :            : 
     118                 :            :     /**
     119                 :            :      * The geometry type of this layer.
     120                 :            :      */
     121                 :            :     QgsWkbTypes::GeometryType geometryType() const;
     122                 :            : 
     123                 :            :     /**
     124                 :            :      * The coordinate reference system of this layer.
     125                 :            :      */
     126                 :            :     QgsCoordinateReferenceSystem crs() const;
     127                 :            : 
     128                 :            :     /**
     129                 :            :      * Returns the name of the layer.
     130                 :            :      *
     131                 :            :      * Should be preferred over layer().name() because it can directly be run on
     132                 :            :      * the background thread.
     133                 :            :      */
     134                 :            :     QString layerName() const;
     135                 :            : 
     136                 :            :   protected:
     137                 :            : 
     138                 :            :     /**
     139                 :            :      * Inserts a feature into the cache and the spatial index.
     140                 :            :      * To be used by implementations of ``addFeature``.
     141                 :            :      */
     142                 :            :     void insertFeature( const QgsFeature &feature, bool skipLock = false );
     143                 :            : 
     144                 :            :     /**
     145                 :            :      * Changes a feature in the cache and the spatial index.
     146                 :            :      * To be used by implementations of ``updateFeature``.
     147                 :            :      */
     148                 :            :     void refreshCache( const QgsFeature &feature );
     149                 :            : 
     150                 :            :     /**
     151                 :            :      * Removes a feature from the cache and the spatial index.
     152                 :            :      * To be used by implementations of ``deleteFeature``.
     153                 :            :      */
     154                 :            :     void removeFeature( const QgsFeatureId featureId );
     155                 :            : 
     156                 :            :     /**
     157                 :            :      * Sets all the feature ids governed by this feature pool.
     158                 :            :      * Should be called by subclasses constructor and whenever
     159                 :            :      * they insert a new feature.
     160                 :            :      *
     161                 :            :      * \note not available in Python bindings
     162                 :            :      */
     163                 :            :     void setFeatureIds( const QgsFeatureIds &ids ) SIP_SKIP;
     164                 :            : 
     165                 :            :     /**
     166                 :            :      * Checks if the feature \a fid is cached.
     167                 :            :      *
     168                 :            :      * \note not available in Python bindings
     169                 :            :      * \since QGIS 3.4
     170                 :            :      */
     171                 :            :     bool isFeatureCached( QgsFeatureId fid ) SIP_SKIP;
     172                 :            : 
     173                 :            :   private:
     174                 :            : #ifdef SIP_RUN
     175                 :            :     QgsFeaturePool( const QgsFeaturePool &other )
     176                 :            :     {}
     177                 :            : #endif
     178                 :            : 
     179                 :            :     static const int CACHE_SIZE = 1000;
     180                 :            :     QCache<QgsFeatureId, QgsFeature> mFeatureCache;
     181                 :            :     QPointer<QgsVectorLayer> mLayer;
     182                 :            :     mutable QReadWriteLock mCacheLock;
     183                 :            :     QgsFeatureIds mFeatureIds;
     184                 :            :     QgsSpatialIndex mIndex;
     185                 :            :     QgsWkbTypes::GeometryType mGeometryType;
     186                 :            :     std::unique_ptr<QgsVectorLayerFeatureSource> mFeatureSource;
     187                 :            :     QString mLayerName;
     188                 :            : };
     189                 :            : 
     190                 :            : #endif // QGS_FEATUREPOOL_H