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[FEATURE][processing] Package layers algorithm
Allows multiple vector layers to be collected together into a geopackage database output Previously all existing methods avilable in QGIS rely on adding layers one-at-a-time, which is tedious for large numbers of layers. Sponsored by SMEC
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‎src/analysis/CMakeLists.txt

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@@ -46,6 +46,7 @@ SET(QGIS_ANALYSIS_SRCS
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processing/qgsalgorithmminimumenclosingcircle.cpp
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processing/qgsalgorithmmultiparttosinglepart.cpp
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processing/qgsalgorithmorientedminimumboundingbox.cpp
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processing/qgsalgorithmpackage.cpp
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processing/qgsalgorithmpromotetomultipart.cpp
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processing/qgsalgorithmrasterlayeruniquevalues.cpp
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processing/qgsalgorithmremovenullgeometry.cpp

‎src/analysis/processing/qgsalgorithmpackage.cpp

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/***************************************************************************
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qgsalgorithmpackage.cpp
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---------------------
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begin : November 2017
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copyright : (C) 2017 by Nyall Dawson
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email : nyall dot dawson at gmail dot com
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***************************************************************************/
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/***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************/
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#include "qgsalgorithmpackage.h"
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#include "qgsgeometryengine.h"
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#include "qgsogrutils.h"
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#include "qgsvectorfilewriter.h"
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///@cond PRIVATE
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QString QgsPackageAlgorithm::name() const
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{
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return QStringLiteral( "package" );
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}
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QString QgsPackageAlgorithm::displayName() const
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{
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return QObject::tr( "Package layers" );
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}
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QStringList QgsPackageAlgorithm::tags() const
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{
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return QObject::tr( "geopackage,collect,merge,combine" ).split( ',' );
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}
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QString QgsPackageAlgorithm::group() const
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{
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return QObject::tr( "Database" );
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}
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void QgsPackageAlgorithm::initAlgorithm( const QVariantMap & )
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{
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addParameter( new QgsProcessingParameterMultipleLayers( QStringLiteral( "LAYERS" ), QObject::tr( "Input layers" ), QgsProcessing::TypeVector ) );
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addParameter( new QgsProcessingParameterFileDestination( QStringLiteral( "OUTPUT" ), QObject::tr( "Destination GeoPackage" ), QStringLiteral( "*.gpkg" ) ) );
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addParameter( new QgsProcessingParameterBoolean( QStringLiteral( "OVERWRITE" ), QObject::tr( "Overwrite existing GeoPackage" ), false ) );
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}
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QString QgsPackageAlgorithm::shortHelpString() const
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{
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return QObject::tr( "This algorithm collects a number of existing layers and packages them together into a single GeoPackage database." );
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}
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QgsPackageAlgorithm *QgsPackageAlgorithm::createInstance() const
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{
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return new QgsPackageAlgorithm();
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}
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QVariantMap QgsPackageAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
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{
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bool overwrite = parameterAsBool( parameters, QStringLiteral( "OVERWRITE" ), context );
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QString packagePath = parameterAsString( parameters, QStringLiteral( "OUTPUT" ), context );
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if ( packagePath.isEmpty() )
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throw QgsProcessingException( QObject::tr( "No output file specified." ) );
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// delete existing geopackage if it exists
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if ( overwrite && QFile::exists( packagePath ) )
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{
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feedback->pushInfo( QObject::tr( "Removing existing file '%1'" ).arg( packagePath ) );
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if ( !QFile( packagePath ).remove() )
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{
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throw QgsProcessingException( QObject::tr( "Could not remove existing file '%1'" ) );
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}
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}
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OGRSFDriverH hGpkgDriver = OGRGetDriverByName( "GPKG" );
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if ( !hGpkgDriver )
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{
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throw QgsProcessingException( QObject::tr( "GeoPackage driver not found." ) );
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}
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gdal::ogr_datasource_unique_ptr hDS( OGR_Dr_CreateDataSource( hGpkgDriver, packagePath.toUtf8().constData(), nullptr ) );
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if ( !hDS )
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throw QgsProcessingException( QObject::tr( "Creation of database failed (OGR error: %1)" ).arg( QString::fromUtf8( CPLGetLastErrorMsg() ) ) );
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bool errored = false;
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const QList< QgsMapLayer * > layers = parameterAsLayerList( parameters, QStringLiteral( "LAYERS" ), context );
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QgsProcessingMultiStepFeedback multiStepFeedback( layers.count(), feedback );
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int i = 0;
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for ( QgsMapLayer *layer : layers )
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{
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if ( feedback->isCanceled() )
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break;
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multiStepFeedback.setCurrentStep( i );
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i++;
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feedback->pushInfo( QObject::tr( "Packaging layer %1/%2: %3" ).arg( i ).arg( layers.count() ).arg( layer->name() ) );
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if ( !layer )
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{
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// don't throw immediately - instead do what we can and error out later
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feedback->pushDebugInfo( QObject::tr( "Error retrieving map layer." ) );
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errored = true;
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continue;
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}
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switch ( layer->type() )
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{
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case QgsMapLayer::VectorLayer:
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{
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if ( !packageVectorLayer( qobject_cast< QgsVectorLayer * >( layer ), packagePath,
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context, &multiStepFeedback ) )
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errored = true;
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break;
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}
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case QgsMapLayer::RasterLayer:
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{
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//not supported
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feedback->pushDebugInfo( QObject::tr( "Raster layers are not currently supported." ) );
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errored = true;
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break;
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}
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case QgsMapLayer::PluginLayer:
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//not supported
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feedback->pushDebugInfo( QObject::tr( "Packaging plugin layers is not supported." ) );
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errored = true;
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break;
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}
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}
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if ( errored )
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throw QgsProcessingException( QObject::tr( "Error obtained while packaging one or more layers." ) );
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QVariantMap outputs;
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outputs.insert( QStringLiteral( "OUTPUT" ), packagePath );
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return outputs;
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}
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bool QgsPackageAlgorithm::packageVectorLayer( QgsVectorLayer *layer, const QString &path, QgsProcessingContext &context,
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QgsProcessingFeedback *feedback )
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{
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QgsVectorFileWriter::SaveVectorOptions options;
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options.driverName = QStringLiteral( "GPKG" );
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options.layerName = layer->name();
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options.actionOnExistingFile = QgsVectorFileWriter::CreateOrOverwriteLayer;
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options.fileEncoding = context.defaultEncoding();
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options.feedback = feedback;
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QString error;
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if ( QgsVectorFileWriter::writeAsVectorFormat( layer, path, options, &error ) != QgsVectorFileWriter::NoError )
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{
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feedback->pushDebugInfo( QObject::tr( "Packaging layer failed: %1" ).arg( error ) );
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return false;
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}
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else
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{
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return true;
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}
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}
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///@endcond

‎src/analysis/processing/qgsalgorithmpackage.h

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/***************************************************************************
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qgsalgorithmpackage.h
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------------------
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begin : November 2017
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copyright : (C) 2017 by Nyall Dawson
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email : nyall dot dawson at gmail dot com
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***************************************************************************/
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/***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************/
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#ifndef QGSALGORITHMPACKAGE_H
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#define QGSALGORITHMPACKAGE_H
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#define SIP_NO_FILE
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#include "qgis.h"
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#include "qgsprocessingalgorithm.h"
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///@cond PRIVATE
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class QgsVectorLayer;
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/**
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* Native package layers algorithm.
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*/
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class QgsPackageAlgorithm : public QgsProcessingAlgorithm
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{
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public:
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QgsPackageAlgorithm() = default;
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void initAlgorithm( const QVariantMap &configuration = QVariantMap() ) override;
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QString name() const override;
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QString displayName() const override;
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virtual QStringList tags() const override;
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QString group() const override;
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QString shortHelpString() const override;
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QgsPackageAlgorithm *createInstance() const override SIP_FACTORY;
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protected:
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virtual QVariantMap processAlgorithm( const QVariantMap &parameters,
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QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
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private:
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bool packageVectorLayer( QgsVectorLayer *layer, const QString &path, QgsProcessingContext &context, QgsProcessingFeedback *feedback );
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};
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///@endcond PRIVATE
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#endif // QGSALGORITHMPACKAGE_H
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‎src/analysis/processing/qgsnativealgorithms.cpp

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#include "qgsalgorithmminimumenclosingcircle.h"
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#include "qgsalgorithmmultiparttosinglepart.h"
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#include "qgsalgorithmorientedminimumboundingbox.h"
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#include "qgsalgorithmpackage.h"
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#include "qgsalgorithmpromotetomultipart.h"
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#include "qgsalgorithmrasterlayeruniquevalues.h"
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#include "qgsalgorithmremovenullgeometry.h"
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addAlgorithm( new QgsMinimumEnclosingCircleAlgorithm() );
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addAlgorithm( new QgsMultipartToSinglepartAlgorithm() );
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addAlgorithm( new QgsOrientedMinimumBoundingBoxAlgorithm() );
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addAlgorithm( new QgsPackageAlgorithm() );
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addAlgorithm( new QgsPromoteToMultipartAlgorithm() );
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addAlgorithm( new QgsRasterLayerUniqueValuesReportAlgorithm() );
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addAlgorithm( new QgsRemoveNullGeometryAlgorithm() );

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