qgsalgorithmfilter.cpp

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/***************************************************************************
                         qgsalgorithmfilter.cpp
                         ---------------------
    begin                : April 2018
    copyright            : (C) 2018 by Matthias Kuhn
    email                : matthias@opengis.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 "qgsalgorithmfilter.h"
#include "qgsapplication.h"
 
 
QString QgsFilterAlgorithm::name() const
{
  return QStringLiteral( "filter" );
}
 
QString QgsFilterAlgorithm::displayName() const
{
  return QObject::tr( "Feature filter" );
}
 
QStringList QgsFilterAlgorithm::tags() const
{
  return QObject::tr( "filter,proxy,redirect,route" ).split( ',' );
}
 
QString QgsFilterAlgorithm::group() const
{
  return QObject::tr( "Modeler tools" );
}
 
QString QgsFilterAlgorithm::groupId() const
{
  return QStringLiteral( "modelertools" );
}
 
Qgis::ProcessingAlgorithmFlags QgsFilterAlgorithm::flags() const
{
  return Qgis::ProcessingAlgorithmFlag::HideFromToolbox;
}
 
QString QgsFilterAlgorithm::shortHelpString() const
{
  return QObject::tr( "This algorithm filters features from the input layer and redirects them to one or several outputs." );
}
 
QgsFilterAlgorithm *QgsFilterAlgorithm::createInstance() const
{
  return new QgsFilterAlgorithm();
}
 
QgsFilterAlgorithm::~QgsFilterAlgorithm()
{
  qDeleteAll( mOutputs );
}
 
void QgsFilterAlgorithm::initAlgorithm( const QVariantMap &configuration )
{
  addParameter( new QgsProcessingParameterFeatureSource( QStringLiteral( "INPUT" ), QObject::tr( "Input layer" ) ) );
 
  const QVariantList outputs = configuration.value( QStringLiteral( "outputs" ) ).toList();
  for ( const QVariant &output : outputs )
  {
    const QVariantMap outputDef = output.toMap();
    const QString name = QStringLiteral( "OUTPUT_%1" ).arg( outputDef.value( QStringLiteral( "name" ) ).toString() );
    QgsProcessingParameterFeatureSink *outputParam = new QgsProcessingParameterFeatureSink( name, outputDef.value( QStringLiteral( "name" ) ).toString() );
    Qgis::ProcessingParameterFlags flags;
    flags |= Qgis::ProcessingParameterFlag::Hidden;
    if ( outputDef.value( QStringLiteral( "isModelOutput" ) ).toBool() )
      flags |= Qgis::ProcessingParameterFlag::IsModelOutput;
    outputParam->setFlags( flags );
    addParameter( outputParam );
    mOutputs.append( new Output( name, outputDef.value( QStringLiteral( "expression" ) ).toString() ) );
  }
}
 
 
QVariantMap QgsFilterAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
{
  std::unique_ptr< QgsProcessingFeatureSource > source( parameterAsSource( parameters, QStringLiteral( "INPUT" ), context ) );
  if ( !source )
    throw QgsProcessingException( invalidSourceError( parameters, QStringLiteral( "INPUT" ) ) );
 
  QgsExpressionContext expressionContext = createExpressionContext( parameters, context, source.get() );
  for ( Output *output : std::as_const( mOutputs ) )
  {
    output->sink.reset( parameterAsSink( parameters, output->name, context, output->destinationIdentifier, source->fields(), source->wkbType(), source->sourceCrs() ) );
    if ( !output->sink )
      throw QgsProcessingException( invalidSinkError( parameters, output->name ) );
    output->expression.prepare( &expressionContext );
  }
 
  long count = source->featureCount();
 
  QgsFeature f;
  QgsFeatureIterator it = source->getFeatures( QgsFeatureRequest(), Qgis::ProcessingFeatureSourceFlag::SkipGeometryValidityChecks );
 
  double step = count > 0 ? 100.0 / count : 1;
  int current = 0;
 
  while ( it.nextFeature( f ) )
  {
    if ( feedback->isCanceled() )
    {
      break;
    }
 
    expressionContext.setFeature( f );
 
    for ( Output *output : std::as_const( mOutputs ) )
    {
      if ( output->expression.evaluate( &expressionContext ).toBool() )
      {
        if ( !output->sink->addFeature( f, QgsFeatureSink::FastInsert ) )
          throw QgsProcessingException( writeFeatureError( output->sink.get(), parameters, output->name ) );
      }
    }
 
    feedback->setProgress( current * step );
    current++;
  }
 
  QVariantMap outputs;
  for ( const Output *output : std::as_const( mOutputs ) )
  {
    outputs.insert( output->name, output->destinationIdentifier );
  }
  qDeleteAll( mOutputs );
  mOutputs.clear();
  return outputs;
}