C++ (Cpp) processFeature示例

示例#1

文件： qgsgeometryvalidationservice.cpp 项目： aaime/QGIS

void QgsGeometryValidationService::onFeatureAdded( QgsVectorLayer *layer, QgsFeatureId fid )
{
  if ( !mLayerChecks[layer].topologyChecks.empty() )
  {
    invalidateTopologyChecks( layer );
  }
  processFeature( layer, fid );
}

示例#2

文件： qgsprocessingalgorithm.cpp 项目： dmarteau/QGIS

QVariantMap QgsProcessingFeatureBasedAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
{
  prepareSource( parameters, context );
  QString dest;
  std::unique_ptr< QgsFeatureSink > sink( parameterAsSink( parameters, QStringLiteral( "OUTPUT" ), context, dest,
                                          outputFields( mSource->fields() ),
                                          outputWkbType( mSource->wkbType() ),
                                          outputCrs( mSource->sourceCrs() ),
                                          sinkFlags() ) );
  if ( !sink )
    throw QgsProcessingException( invalidSinkError( parameters, QStringLiteral( "OUTPUT" ) ) );

  // prepare expression context for feature iteration
  QgsExpressionContext prevContext = context.expressionContext();
  QgsExpressionContext algContext = prevContext;

  algContext.appendScopes( createExpressionContext( parameters, context, mSource.get() ).takeScopes() );
  context.setExpressionContext( algContext );

  long count = mSource->featureCount();

  QgsFeature f;
  QgsFeatureIterator it = mSource->getFeatures( request(), sourceFlags() );

  double step = count > 0 ? 100.0 / count : 1;
  int current = 0;
  while ( it.nextFeature( f ) )
  {
    if ( feedback->isCanceled() )
    {
      break;
    }

    context.expressionContext().setFeature( f );
    const QgsFeatureList transformed = processFeature( f, context, feedback );
    for ( QgsFeature transformedFeature : transformed )
      sink->addFeature( transformedFeature, QgsFeatureSink::FastInsert );

    feedback->setProgress( current * step );
    current++;
  }

  mSource.reset();

  // probably not necessary - context's aren't usually recycled, but can't hurt
  context.setExpressionContext( prevContext );

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