qgsalgorithmsymmetricaldifference.cpp

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/***************************************************************************
  qgsalgorithmsymmetricaldifference.cpp
  ---------------------
  Date                 : April 2018
  Copyright            : (C) 2018 by Martin Dobias
  Email                : wonder dot sk at gmail dot com
 ***************************************************************************
 *                                                                         *
 *   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 "qgsalgorithmsymmetricaldifference.h"

#include "qgsoverlayutils.h"


QString QgsSymmetricalDifferenceAlgorithm::name() const
{
  return QStringLiteral( "symmetricaldifference" );
}

QString QgsSymmetricalDifferenceAlgorithm::displayName() const
{
  return QObject::tr( "Symmetrical difference" );
}

QString QgsSymmetricalDifferenceAlgorithm::group() const
{
  return QObject::tr( "Vector overlay" );
}

QString QgsSymmetricalDifferenceAlgorithm::groupId() const
{
  return QStringLiteral( "vectoroverlay" );
}

QString QgsSymmetricalDifferenceAlgorithm::shortHelpString() const
{
  return QObject::tr( "This algorithm creates a layer containing features from both the Input and Difference layers but with the overlapping areas between the two layers removed. The attribute table of the Symmetrical Difference layer contains attributes from both the Input and Difference layers." );
}

QgsProcessingAlgorithm *QgsSymmetricalDifferenceAlgorithm::createInstance() const
{
  return new QgsSymmetricalDifferenceAlgorithm();
}

void QgsSymmetricalDifferenceAlgorithm::initAlgorithm( const QVariantMap & )
{
  addParameter( new QgsProcessingParameterFeatureSource( QStringLiteral( "INPUT" ), QObject::tr( "Input layer" ) ) );
  addParameter( new QgsProcessingParameterFeatureSource( QStringLiteral( "OVERLAY" ), QObject::tr( "Difference layer" ) ) );
  addParameter( new QgsProcessingParameterFeatureSink( QStringLiteral( "OUTPUT" ), QObject::tr( "Symmetrical difference" ) ) );
}


QVariantMap QgsSymmetricalDifferenceAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
{
  std::unique_ptr< QgsFeatureSource > sourceA( parameterAsSource( parameters, QStringLiteral( "INPUT" ), context ) );
  if ( !sourceA )
    throw QgsProcessingException( invalidSourceError( parameters, QStringLiteral( "INPUT" ) ) );

  std::unique_ptr< QgsFeatureSource > sourceB( parameterAsSource( parameters, QStringLiteral( "OVERLAY" ), context ) );
  if ( !sourceB )
    throw QgsProcessingException( invalidSourceError( parameters, QStringLiteral( "OVERLAY" ) ) );

  QgsWkbTypes::Type geomType = QgsWkbTypes::multiType( sourceA->wkbType() );

  QgsFields fields = QgsProcessingUtils::combineFields( sourceA->fields(), sourceB->fields() );

  QString dest;
  std::unique_ptr< QgsFeatureSink > sink( parameterAsSink( parameters, QStringLiteral( "OUTPUT" ), context, dest, fields, geomType, sourceA->sourceCrs() ) );
  if ( !sink )
    throw QgsProcessingException( invalidSinkError( parameters, QStringLiteral( "OUTPUT" ) ) );

  QVariantMap outputs;
  outputs.insert( QStringLiteral( "OUTPUT" ), dest );

  int count = 0;
  int total = sourceA->featureCount() + sourceB->featureCount();

  QgsOverlayUtils::difference( *sourceA.get(), *sourceB.get(), *sink.get(), context, feedback, count, total, QgsOverlayUtils::OutputAB );

  QgsOverlayUtils::difference( *sourceB.get(), *sourceA.get(), *sink.get(), context, feedback, count, total, QgsOverlayUtils::OutputBA );

  return outputs;
}