qgscachedfeatureiterator.cpp

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/***************************************************************************
    qgscachedfeatureiterator.cpp
     --------------------------------------
    Date                 : 12.2.2013
    Copyright            : (C) 2013 Matthias Kuhn
    Email                : matthias at opengis dot ch
 ***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
 
#include "qgscachedfeatureiterator.h"
#include "qgsvectorlayercache.h"
#include "qgsexception.h"
#include "qgsvectorlayer.h"
#include "qgsgeometryengine.h"
 
QgsCachedFeatureIterator::QgsCachedFeatureIterator( QgsVectorLayerCache *vlCache, const QgsFeatureRequest &featureRequest )
  : QgsAbstractFeatureIterator( featureRequest )
  , mVectorLayerCache( vlCache )
{
  if ( mRequest.destinationCrs().isValid() && mRequest.destinationCrs() != mVectorLayerCache->sourceCrs() )
  {
    mTransform = QgsCoordinateTransform( mVectorLayerCache->sourceCrs(), mRequest.destinationCrs(), mRequest.transformContext() );
  }
  try
  {
    mFilterRect = filterRectToSourceCrs( mTransform );
  }
  catch ( QgsCsException & )
  {
    // can't reproject mFilterRect
    close();
    return;
  }
 
  // prepare spatial filter geometries for optimal speed
  switch ( mRequest.spatialFilterType() )
  {
    case Qgis::SpatialFilterType::NoFilter:
    case Qgis::SpatialFilterType::BoundingBox:
      break;
 
    case Qgis::SpatialFilterType::DistanceWithin:
      if ( !mRequest.referenceGeometry().isEmpty() )
      {
        mDistanceWithinGeom = mRequest.referenceGeometry();
        mDistanceWithinEngine.reset( QgsGeometry::createGeometryEngine( mDistanceWithinGeom.constGet() ) );
        mDistanceWithinEngine->prepareGeometry();
        mDistanceWithin = mRequest.distanceWithin();
      }
      break;
  }
 
  if ( !mFilterRect.isNull() )
  {
    // update request to be the unprojected filter rect
    mRequest.setFilterRect( mFilterRect );
  }
 
  switch ( featureRequest.filterType() )
  {
    case Qgis::FeatureRequestFilterType::Fids:
    {
      const QgsFeatureIds filterFids = featureRequest.filterFids();
      mFeatureIds = QList< QgsFeatureId >( filterFids.begin(), filterFids.end() );
      break;
    }
 
    case Qgis::FeatureRequestFilterType::Fid:
      mFeatureIds = QList< QgsFeatureId >() << featureRequest.filterFid();
      break;
 
    case Qgis::FeatureRequestFilterType::Expression:
    case Qgis::FeatureRequestFilterType::NoFilter:
      mFeatureIds = QList( mVectorLayerCache->mCacheOrderedKeys.begin(), mVectorLayerCache->mCacheOrderedKeys.end() );
      break;
  }
 
  mFeatureIdIterator = mFeatureIds.constBegin();
 
  if ( mFeatureIdIterator == mFeatureIds.constEnd() )
    close();
}
 
QgsCachedFeatureIterator::~QgsCachedFeatureIterator() = default;
 
bool QgsCachedFeatureIterator::fetchFeature( QgsFeature &f )
{
  f.setValid( false );
 
  if ( mClosed )
    return false;
 
  while ( mFeatureIdIterator != mFeatureIds.constEnd() )
  {
    if ( !mVectorLayerCache->mCache.contains( *mFeatureIdIterator ) )
    {
      ++mFeatureIdIterator;
      continue;
    }
 
    f = QgsFeature( *mVectorLayerCache->mCache[*mFeatureIdIterator]->feature() );
    ++mFeatureIdIterator;
    if ( mRequest.acceptFeature( f ) )
    {
      f.setValid( true );
      geometryToDestinationCrs( f, mTransform );
 
      bool result = true;
      if ( mDistanceWithinEngine && mDistanceWithinEngine->distance( f.geometry().constGet() ) > mDistanceWithin )
      {
        f.setValid( false );
        result = false;
      }
 
      if ( result )
        return true;
    }
  }
  close();
  return false;
}
 
bool QgsCachedFeatureIterator::rewind()
{
  mFeatureIdIterator = mFeatureIds.constBegin();
  return true;
}
 
bool QgsCachedFeatureIterator::close()
{
  mClosed = true;
  mFeatureIds.clear();
  return true;
}
 
QgsCachedFeatureWriterIterator::QgsCachedFeatureWriterIterator( QgsVectorLayerCache *vlCache, const QgsFeatureRequest &featureRequest )
  : QgsAbstractFeatureIterator( featureRequest )
  , mVectorLayerCache( vlCache )
{
  if ( mRequest.destinationCrs().isValid() && mRequest.destinationCrs() != mVectorLayerCache->sourceCrs() )
  {
    mTransform = QgsCoordinateTransform( mVectorLayerCache->sourceCrs(), mRequest.destinationCrs(), mRequest.transformContext() );
  }
  try
  {
    mFilterRect = filterRectToSourceCrs( mTransform );
  }
  catch ( QgsCsException & )
  {
    // can't reproject mFilterRect
    close();
    return;
  }
  if ( !mFilterRect.isNull() )
  {
    // update request to be the unprojected filter rect
    mRequest.setFilterRect( mFilterRect );
  }
 
  mFeatIt = vlCache->layer()->getFeatures( mRequest );
}
 
bool QgsCachedFeatureWriterIterator::fetchFeature( QgsFeature &f )
{
  if ( mClosed )
  {
    f.setValid( false );
    return false;
  }
  if ( mFeatIt.nextFeature( f ) )
  {
    // As long as features can be fetched from the provider: Write them to cache
    mVectorLayerCache->cacheFeature( f, ! mRequest.flags().testFlag( Qgis::FeatureRequestFlag::SubsetOfAttributes ) );
    mFids.insert( f.id() );
    geometryToDestinationCrs( f, mTransform );
    return true;
  }
  else
  {
    // Once no more features can be fetched: Inform the cache, that
    // the request has been completed
    mVectorLayerCache->requestCompleted( mRequest, mFids );
    return false;
  }
}
 
bool QgsCachedFeatureWriterIterator::rewind()
{
  mFids.clear();
  return mFeatIt.rewind();
}
 
bool QgsCachedFeatureWriterIterator::close()
{
  mClosed = true;
  return mFeatIt.close();
}