QGIS API Documentation  2.15.0-Master (13f053b)
qgscachedfeatureiterator.cpp
Go to the documentation of this file.
1 /***************************************************************************
2  qgscachedfeatureiterator.cpp
3  --------------------------------------
4  Date : 12.2.2013
5  Copyright : (C) 2013 Matthias Kuhn
6  Email : matthias at opengis dot ch
7  ***************************************************************************
8  * *
9  * This program is free software; you can redistribute it and/or modify *
10  * it under the terms of the GNU General Public License as published by *
11  * the Free Software Foundation; either version 2 of the License, or *
12  * (at your option) any later version. *
13  * *
14  ***************************************************************************/
15 
17 #include "qgsvectorlayercache.h"
18 
20  : QgsAbstractFeatureIterator( featureRequest )
21  , mFeatureIds( featureIds )
22  , mVectorLayerCache( vlCache )
23 {
24  mFeatureIdIterator = featureIds.constBegin();
25 
26  if ( mFeatureIdIterator == featureIds.constEnd() )
27  close();
28 }
29 
31  : QgsAbstractFeatureIterator( featureRequest )
32  , mVectorLayerCache( vlCache )
33 {
34  switch ( featureRequest.filterType() )
35  {
37  mFeatureIds = featureRequest.filterFids();
38  break;
39 
41  mFeatureIds = QgsFeatureIds() << featureRequest.filterFid();
42  break;
43 
44  default:
45  mFeatureIds = mVectorLayerCache->mCache.keys().toSet();
46  break;
47  }
48 
49  mFeatureIdIterator = mFeatureIds.constBegin();
50 
51  if ( mFeatureIdIterator == mFeatureIds.constEnd() )
52  close();
53 }
54 
56 {
57  if ( mClosed )
58  return false;
59 
60  while ( mFeatureIdIterator != mFeatureIds.constEnd() )
61  {
62  f = QgsFeature( *mVectorLayerCache->mCache[*mFeatureIdIterator]->feature() );
63  ++mFeatureIdIterator;
64  if ( mRequest.acceptFeature( f ) )
65  return true;
66  }
67  close();
68  return false;
69 }
70 
72 {
73  mFeatureIdIterator = mFeatureIds.constBegin();
74  return true;
75 }
76 
78 {
79  mClosed = true;
80  mFeatureIds.clear();
81  return true;
82 }
83 
85  : QgsAbstractFeatureIterator( featureRequest )
86  , mVectorLayerCache( vlCache )
87 {
88  mFeatIt = vlCache->layer()->getFeatures( featureRequest );
89 }
90 
92 {
93  if ( mFeatIt.nextFeature( f ) )
94  {
95  // As long as features can be fetched from the provider: Write them to cache
96  mVectorLayerCache->cacheFeature( f );
97  mFids.insert( f.id() );
98  return true;
99  }
100  else
101  {
102  // Once no more features can be fetched: Inform the cache, that
103  // the request has been completed
104  mVectorLayerCache->requestCompleted( mRequest, mFids );
105  return false;
106  }
107 }
108 
110 {
111  mFids.clear();
112  return mFeatIt.rewind();
113 }
114 
116 {
117  mClosed = true;
118  return mFeatIt.close();
119 }
QgsFeatureId id() const
Get the feature ID for this feature.
Definition: qgsfeature.cpp:65
bool acceptFeature(const QgsFeature &feature)
Check if a feature is accepted by this requests filter.
Filter using feature ID.
Filter using feature IDs.
QgsFeatureId filterFid() const
Get the feature ID that should be fetched.
QSet< QgsFeatureId > QgsFeatureIds
Definition: qgsfeature.h:439
QgsFeatureIterator getFeatures(const QgsFeatureRequest &request=QgsFeatureRequest())
Query the provider for features specified in request.
const QgsFeatureIds & filterFids() const
Get feature IDs that should be fetched.
virtual bool fetchFeature(QgsFeature &f) override
Implementation for fetching a feature.
void requestCompleted(const QgsFeatureRequest &featureRequest, const QgsFeatureIds &fids)
Gets called, whenever the full list of feature ids for a certain request is known.
QgsVectorLayer * layer()
Returns the layer to which this cache belongs.
bool mClosed
Set to true, as soon as the iterator is closed.
const_iterator insert(const T &value)
The feature class encapsulates a single feature including its id, geometry and a list of field/values...
Definition: qgsfeature.h:187
Internal feature iterator to be implemented within data providers.
virtual bool close() override
Close this iterator.
This class wraps a request for features to a vector layer (or directly its vector data provider)...
const_iterator constEnd() const
FilterType filterType() const
Return the filter type which is currently set on this request.
virtual bool close() override
Close this iterator.
virtual bool rewind() override
Rewind to the beginning of the iterator.
This class caches features of a given QgsVectorLayer.
const_iterator constBegin() const
QgsFeatureRequest mRequest
A copy of the feature request.
QList< Key > keys() const
virtual bool rewind() override
Rewind to the beginning of the iterator.
Q_DECL_DEPRECATED QgsCachedFeatureIterator(QgsVectorLayerCache *vlCache, const QgsFeatureRequest &featureRequest, const QgsFeatureIds &featureIds)
This constructor creates a feature iterator, that delivers only cached information, based on the QgsFeatureIds.
bool nextFeature(QgsFeature &f)
void clear()
virtual bool fetchFeature(QgsFeature &f) override
Implementation for fetching a feature.
QgsCachedFeatureWriterIterator(QgsVectorLayerCache *vlCache, const QgsFeatureRequest &featureRequest)
This constructor creates a feature iterator, which queries the backend and caches retrieved features...