qgsalgorithmcheckgeometrysliverpolygon.cpp

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/***************************************************************************
                        qgsalgorithmcheckgeometrysliverpolygon.cpp
                        ---------------------
   begin                : April 2025
   copyright            : (C) 2025 by Jacky Volpes
   email                : jacky dot volpes at oslandia 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 "qgsalgorithmcheckgeometrysliverpolygon.h"
 
#include "qgsgeometrycheckcontext.h"
#include "qgsgeometrycheckerror.h"
#include "qgsgeometrysliverpolygoncheck.h"
#include "qgspoint.h"
#include "qgsvectordataproviderfeaturepool.h"
#include "qgsvectorlayer.h"
 
#include <QString>
 
using namespace Qt::StringLiterals;

 
QString QgsGeometryCheckSliverPolygonAlgorithm::name() const
{
  return u"checkgeometrysliverpolygon"_s;
}
 
QString QgsGeometryCheckSliverPolygonAlgorithm::displayName() const
{
  return QObject::tr( "Sliver polygons" );
}
 
QString QgsGeometryCheckSliverPolygonAlgorithm::shortDescription() const
{
  return QObject::tr( "Detects sliver polygons that are too thin." );
}
 
QStringList QgsGeometryCheckSliverPolygonAlgorithm::tags() const
{
  return QObject::tr( "check,geometry,sliver,polygon" ).split( ',' );
}
 
QString QgsGeometryCheckSliverPolygonAlgorithm::group() const
{
  return QObject::tr( "Check geometry" );
}
 
QString QgsGeometryCheckSliverPolygonAlgorithm::groupId() const
{
  return u"checkgeometry"_s;
}
 
QString QgsGeometryCheckSliverPolygonAlgorithm::shortHelpString() const
{
  return QObject::tr(
    "This algorithm checks sliver polygons.\n\n"
    "The thinness is the ratio between the area of the minimum square containing the polygon and the area of the polygon itself "
    "(a square has a thinness value of  1).\n"
    "The thinness value is between 1 and +infinity.\n"
    "If a polygon has an area higher than the maximum area, it is skipped (a maximum area value of 0 means no area check).\n\n"
    "Polygons having a thinness higher than the maximum thinness are errors.\n\n"
    "To fix sliver polygons, use the \"Fix small polygons\" algorithm."
  );
}
 
Qgis::ProcessingAlgorithmFlags QgsGeometryCheckSliverPolygonAlgorithm::flags() const
{
  return QgsProcessingAlgorithm::flags() | Qgis::ProcessingAlgorithmFlag::NoThreading | Qgis::ProcessingAlgorithmFlag::RequiresProject;
}
 
QgsGeometryCheckSliverPolygonAlgorithm *QgsGeometryCheckSliverPolygonAlgorithm::createInstance() const
{
  return new QgsGeometryCheckSliverPolygonAlgorithm();
}
 
void QgsGeometryCheckSliverPolygonAlgorithm::initAlgorithm( const QVariantMap &configuration )
{
  Q_UNUSED( configuration )
 
  addParameter( new QgsProcessingParameterFeatureSource( u"INPUT"_s, QObject::tr( "Input layer" ), QList<int>() << static_cast<int>( Qgis::ProcessingSourceType::VectorPolygon ) ) );
  addParameter( new QgsProcessingParameterField( u"UNIQUE_ID"_s, QObject::tr( "Unique feature identifier" ), QString(), u"INPUT"_s ) );
  addParameter( new QgsProcessingParameterFeatureSink( u"ERRORS"_s, QObject::tr( "Sliver polygon errors" ), Qgis::ProcessingSourceType::VectorPoint ) );
  addParameter( new QgsProcessingParameterFeatureSink( u"OUTPUT"_s, QObject::tr( "Sliver polygon features" ), Qgis::ProcessingSourceType::VectorPolygon, QVariant(), true, false ) );
 
  addParameter( new QgsProcessingParameterNumber( u"MAX_THINNESS"_s, QObject::tr( "Maximum thinness" ), Qgis::ProcessingNumberParameterType::Double, 20, false, 1.0 ) );
  addParameter( new QgsProcessingParameterNumber( u"MAX_AREA"_s, QObject::tr( "Maximum area (map units squared)" ), Qgis::ProcessingNumberParameterType::Double, 0, false, 0.0 ) );
 
  auto tolerance = std::make_unique<QgsProcessingParameterNumber>( u"TOLERANCE"_s, QObject::tr( "Tolerance" ), Qgis::ProcessingNumberParameterType::Integer, 8, false, 1, 13 );
  tolerance->setFlags( tolerance->flags() | Qgis::ProcessingParameterFlag::Advanced );
  tolerance->setHelp(
    QObject::tr(
      "The \"Tolerance\" advanced parameter defines the numerical precision of geometric operations, "
      "given as an integer n, meaning that any difference smaller than 10⁻ⁿ (in map units) is considered zero."
    )
  );
  addParameter( tolerance.release() );
}
 
bool QgsGeometryCheckSliverPolygonAlgorithm::prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback * )
{
  mTolerance = parameterAsInt( parameters, u"TOLERANCE"_s, context );
 
  return true;
}
 
QgsFields QgsGeometryCheckSliverPolygonAlgorithm::outputFields()
{
  QgsFields fields;
  fields.append( QgsField( u"gc_layerid"_s, QMetaType::QString ) );
  fields.append( QgsField( u"gc_layername"_s, QMetaType::QString ) );
  fields.append( QgsField( u"gc_partidx"_s, QMetaType::Int ) );
  fields.append( QgsField( u"gc_ringidx"_s, QMetaType::Int ) );
  fields.append( QgsField( u"gc_vertidx"_s, QMetaType::Int ) );
  fields.append( QgsField( u"gc_errorx"_s, QMetaType::Double ) );
  fields.append( QgsField( u"gc_errory"_s, QMetaType::Double ) );
  fields.append( QgsField( u"gc_error"_s, QMetaType::QString ) );
  return fields;
}
 
QVariantMap QgsGeometryCheckSliverPolygonAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
{
  QString dest_output;
  QString dest_errors;
  const std::unique_ptr<QgsProcessingFeatureSource> input( parameterAsSource( parameters, u"INPUT"_s, context ) );
  if ( !input )
    throw QgsProcessingException( invalidSourceError( parameters, u"INPUT"_s ) );
 
  const QString uniqueIdFieldName( parameterAsString( parameters, u"UNIQUE_ID"_s, context ) );
  const int uniqueIdFieldIdx = input->fields().indexFromName( uniqueIdFieldName );
  if ( uniqueIdFieldIdx == -1 )
    throw QgsProcessingException( QObject::tr( "Missing field %1 in input layer" ).arg( uniqueIdFieldName ) );
 
  const QgsField uniqueIdField = input->fields().at( uniqueIdFieldIdx );
 
  QgsFields fields = outputFields();
  fields.append( uniqueIdField );
 
  const std::unique_ptr<QgsFeatureSink> sink_output( parameterAsSink( parameters, u"OUTPUT"_s, context, dest_output, fields, input->wkbType(), input->sourceCrs() ) );
 
  const std::unique_ptr<QgsFeatureSink> sink_errors( parameterAsSink( parameters, u"ERRORS"_s, context, dest_errors, fields, Qgis::WkbType::Point, input->sourceCrs() ) );
  if ( !sink_errors )
    throw QgsProcessingException( invalidSinkError( parameters, u"ERRORS"_s ) );
 
  QgsProcessingMultiStepFeedback multiStepFeedback( 3, feedback );
 
  // Test detection
  QList<QgsGeometryCheckError *> checkErrors;
  QStringList messages;
 
  const double maxThinness = parameterAsDouble( parameters, u"MAX_THINNESS"_s, context );
  const double maxArea = parameterAsDouble( parameters, u"MAX_AREA"_s, context );
 
  QVariantMap configurationCheck;
  configurationCheck.insert( "maxArea", maxArea );
  configurationCheck.insert( "threshold", maxThinness );
 
  QgsGeometryCheckContext checkContext = QgsGeometryCheckContext( mTolerance, input->sourceCrs(), context.transformContext(), context.project(), uniqueIdFieldIdx );
  const QgsGeometrySliverPolygonCheck check( &checkContext, configurationCheck );
 
  multiStepFeedback.setCurrentStep( 1 );
  feedback->setProgressText( QObject::tr( "Preparing features…" ) );
  QMap<QString, QgsFeaturePool *> checkerFeaturePools;
 
  std::unique_ptr<QgsVectorLayer> inputLayer( input->materialize( QgsFeatureRequest() ) );
  QgsVectorDataProviderFeaturePool featurePool = QgsVectorDataProviderFeaturePool( inputLayer.get() );
  checkerFeaturePools.insert( inputLayer->id(), &featurePool );
 
  multiStepFeedback.setCurrentStep( 2 );
  feedback->setProgressText( QObject::tr( "Collecting errors…" ) );
  QgsGeometryCheck::Result res = check.collectErrors( checkerFeaturePools, checkErrors, messages, feedback );
  if ( res == QgsGeometryCheck::Result::Success )
  {
    feedback->pushInfo( QObject::tr( "Errors collected successfully." ) );
  }
  else if ( res == QgsGeometryCheck::Result::Canceled )
  {
    throw QgsProcessingException( QObject::tr( "Operation was canceled." ) );
  }
  else if ( res == QgsGeometryCheck::Result::DuplicatedUniqueId )
  {
    throw QgsProcessingException( QObject::tr( "Field '%1' contains non-unique values and can not be used as unique ID." ).arg( uniqueIdFieldName ) );
  }
 
  multiStepFeedback.setCurrentStep( 3 );
  feedback->setProgressText( QObject::tr( "Exporting errors…" ) );
  const double step { checkErrors.size() > 0 ? 100.0 / checkErrors.size() : 1 };
  long i = 0;
  feedback->setProgress( 0.0 );
 
  for ( const QgsGeometryCheckError *error : checkErrors )
  {
    if ( feedback->isCanceled() )
    {
      break;
    }
    QgsFeature f;
    QgsAttributes attrs = f.attributes();
 
    attrs
      << error->layerId()
      << inputLayer->name()
      << error->vidx().part
      << error->vidx().ring
      << error->vidx().vertex
      << error->location().x()
      << error->location().y()
      << error->value().toString()
      << inputLayer->getFeature( error->featureId() ).attribute( uniqueIdField.name() );
    f.setAttributes( attrs );
 
    f.setGeometry( error->geometry() );
    if ( sink_output && !sink_output->addFeature( f, QgsFeatureSink::FastInsert ) )
      throw QgsProcessingException( writeFeatureError( sink_output.get(), parameters, u"OUTPUT"_s ) );
 
    f.setGeometry( QgsGeometry::fromPoint( QgsPoint( error->location().x(), error->location().y() ) ) );
    if ( !sink_errors->addFeature( f, QgsFeatureSink::FastInsert ) )
      throw QgsProcessingException( writeFeatureError( sink_errors.get(), parameters, u"ERRORS"_s ) );
 
    i++;
    feedback->setProgress( 100.0 * step * static_cast<double>( i ) );
  }
 
  // Place the point layer above the polygon layer
  if ( context.willLoadLayerOnCompletion( dest_output ) && context.willLoadLayerOnCompletion( dest_errors ) )
  {
    context.layerToLoadOnCompletionDetails( dest_errors ).layerSortKey = 0;
    context.layerToLoadOnCompletionDetails( dest_output ).layerSortKey = 1;
  }
 
  // cleanup memory of the pointed data
  for ( const QgsGeometryCheckError *error : checkErrors )
  {
    delete error;
  }
 
  QVariantMap outputs;
  if ( sink_output )
    outputs.insert( u"OUTPUT"_s, dest_output );
  outputs.insert( u"ERRORS"_s, dest_errors );
 
  return outputs;
}