rework algorithm

qgis · Oct 24, 2021 · 7f22063 · 7f22063
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diff --git a/src/analysis/processing/qgsalgorithmshortestline.cpp b/src/analysis/processing/qgsalgorithmshortestline.cpp
@@ -1,6 +1,164 @@
+/***************************************************************************
+                         qgsalgorithmshortestline.cpp
+                         ---------------------
+    begin                : September 2021
+    copyright            : (C) 2020 by Matteo Ghetta, Clemens Raffler
+    email                : clemens dot raffler 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.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+//Disclaimer:This feature was originally developed in Python by: Matteo Ghetta, August 2021
+
 #include "qgsalgorithmshortestline.h"
 
-qgsalgorithmshortestline::qgsalgorithmshortestline()
+QString QgsShortestLineAlgorithm::name() const
+{
+  return QStringLiteral( "shortestline" );
+}
+
+QString QgsShortestLineAlgorithm::displayName() const
+{
+  return QObject::tr( "Shortest line between layers" );
+}
+
+QStringList QgsShortestLineAlgorithm::tags() const
+{
+  return QObject::tr( "distance,shortest,minimum,nearest" ).split( ',' );
+}
+
+QString QgsShortestLineAlgorithm::group() const
+{
+  return QObject::tr( "Vector analysis" );
+}
+
+QString QgsShortestLineAlgorithm::groupId() const
 {
+  return QStringLiteral( "vectoranalysis" );
+}
+
+QString QgsShortestLineAlgorithm::shortHelpString() const
+{
+  return QObject::tr( "This algorithm creates a line layer as the "
+                      "shortest line between the source and the destination layer. "
+                      "By default only the first nearest feature of the "
+                      "destination layer is taken into account. "
+                      "The n-nearest neighboring features number can be specified. "
+                      "If a maximum distance is specified, then only "
+                      "features which are closer than this distance will "
+                      "be considered. The output features will contain all the "
+                      "source layer attributes, all the attributes from the n-nearest "
+                      "feature and the additional field of the distance. "
+                      "This algorithm uses purely Cartesian calculations for distance, "
+                      "and does not consider geodetic or ellipsoid properties when "
+                      "determining feature proximity."
+                    );
+}
+
+QgsShortestLineAlgorithm *QgsShortestLineAlgorithm::createInstance() const
+{
+  return new QgsShortestLineAlgorithm();
+}
+
+void QgsShortestLineAlgorithm::initAlgorithm( const QVariantMap & )
+{
+  addParameter( new QgsProcessingParameterFeatureSource( QStringLiteral( "SOURCE" ), QObject::tr( "Source layer" ), QList<int>() << QgsProcessing::TypeVectorAnyGeometry ) );
+  addParameter( new QgsProcessingParameterFeatureSource( QStringLiteral( "DESTINATION" ), QObject::tr( "Destination layer" ), QList<int>() << QgsProcessing::TypeVectorAnyGeometry ) );
+  addParameter( new QgsProcessingParameterNumber( QStringLiteral( "NEIGHBORS" ), QObject::tr( "Maximum number of neighbors" ), QgsProcessingParameterNumber::Integer, 1, false, 1) );
+  addParameter( new QgsProcessingParameterDistance( QStringLiteral( "DISTANCE"), QObject::tr( "Maximum distance" ), QVariant(), QString("SOURCE"), true ) );
+  addParameter( new QgsProcessingParameterFeatureSink( QStringLiteral( "OUTPUT" ), QObject::tr("Shortest lines") ) );
+}
+
+bool QgsShortestLineAlgorithm::prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback * )
+{
+  mSource.reset( parameterAsSource( parameters, QStringLiteral( "SOURCE" ), context) );
+  if ( !mSource )
+    throw QgsProcessingException( invalidSourceError( parameters, QStringLiteral( "SOURCE" ) ) );
+
+  mDestination.reset( parameterAsSource( parameters, QStringLiteral( "DESTINATION" ), context) );
+  if ( !mSource )
+    throw QgsProcessingException( invalidSourceError( parameters, QStringLiteral( "DESTINATION" ) ) );
+
+  mKNeighbors = parameterAsInt( parameters, QStringLiteral( "NEIGHBORS" ), context );
+
+  double paramMaxDist = parameterAsDouble( parameters, QStringLiteral( "DISTANCE" ), context ); //defaults to zero if not set
+  if(paramMaxDist)
+    mMaxDistance = paramMaxDist;
+
+  return true;
+}
+
+QVariantMap QgsShortestLineAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
+{
+  if(mKNeighbors > mDestination->featureCount())
+    mKNeighbors = mDestination->featureCount();
+
+  QgsFields fields = QgsProcessingUtils::combineFields( mSource->fields(), mDestination->fields());
+  fields.append( QgsField( QStringLiteral( "distance" ), QVariant::Double ) );
+
+  QString dest;
+  std::unique_ptr< QgsFeatureSink > sink( parameterAsSink( parameters, QStringLiteral( "OUTPUT" ), context, dest, fields, QgsWkbTypes::MultiLineString, mSource->sourceCrs() ) );
+  if ( !sink )
+    throw QgsProcessingException( invalidSinkError( parameters, QStringLiteral( "OUTPUT" ) ) );
+
+  QgsFeatureRequest request = QgsFeatureRequest();
+  request.setDestinationCrs( mSource->sourceCrs(), context.transformContext() );
+
+  QgsSpatialIndex idx = QgsSpatialIndex( mDestination->getFeatures(request), nullptr, QgsSpatialIndex::FlagStoreFeatureGeometries );
+
+  QgsFeatureIterator sourceIterator = mSource->getFeatures();
+  double step = mSource->featureCount() > 0 ? 100.0 / mSource->featureCount() : 1;
+
+  QgsDistanceArea da = QgsDistanceArea();
+  da.setSourceCrs(mSource->sourceCrs(), context.transformContext());
+  da.setEllipsoid(context.ellipsoid());
+
+  int i = 0;
+  QgsFeature sourceFeature;
+  while ( sourceIterator.nextFeature( sourceFeature ) )
+  {
+    if(feedback->isCanceled())
+      break;
+
+
+    QgsGeometry sourceGeom = sourceFeature.geometry();
+    QgsFeatureIds nearestIds = idx.nearestNeighbor(sourceGeom, mKNeighbors, mMaxDistance).toSet();
+
+    QgsFeatureRequest targetRequest = QgsFeatureRequest();
+    targetRequest.setFilterFids( nearestIds );
+
+    QgsFeatureIterator destinationIterator = mDestination->getFeatures(targetRequest);
+    QgsFeature destinationFeature;
+    while ( destinationIterator.nextFeature(destinationFeature) )
+    {
+      QgsGeometry destinationGeom = destinationFeature.geometry();
+
+      QgsGeometry shortestLine = sourceGeom.shortestLine(destinationGeom);
+      double dist = da.measureLength(shortestLine);
+
+      QgsFeature f;
+
+      QgsAttributes attrs = sourceFeature.attributes();
+      attrs << destinationFeature.attributes() << dist;
+
+      f.setAttributes(attrs);
+      f.setGeometry(shortestLine);
+      sink->addFeature(f, QgsFeatureSink::FastInsert);
+    }
+
+    i++;
+    feedback->setProgress( i * step );
+  }
+
 
+  QVariantMap outputs;
+  outputs.insert( QStringLiteral( "OUTPUT" ), dest );
+  return outputs;
 }
diff --git a/src/analysis/processing/qgsalgorithmshortestline.h b/src/analysis/processing/qgsalgorithmshortestline.h
@@ -1,11 +1,56 @@
+/***************************************************************************
+                         qgsalgorithmshortestline.cpp
+                         ---------------------
+    begin                : September 2021
+    copyright            : (C) 2020 by Matteo Ghetta, Clemens Raffler
+    email                : clemens dot raffler 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.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+//Disclaimer:This feature was originally developed in Python by: Matteo Ghetta, 2021
+
 #ifndef QGSALGORITHMSHORTESTLINE_H
 #define QGSALGORITHMSHORTESTLINE_H
 
+#define SIP_NO_FILE
 
-class qgsalgorithmshortestline
+#include "qgis_sip.h"
+#include "qgsapplication.h"
+#include "qgsprocessingalgorithm.h"
+
+class QgsShortestLineAlgorithm : public QgsProcessingAlgorithm
 {
-public:
-  qgsalgorithmshortestline();
+
+  public:
+    QgsShortestLineAlgorithm() = default;
+    void initAlgorithm( const QVariantMap &configuration = QVariantMap() ) override;
+    QString name() const override;
+    QString displayName() const override;
+    QStringList tags() const override;
+    QString group() const override;
+    QString groupId() const override;
+    QString shortHelpString() const override;
+    QgsShortestLineAlgorithm *createInstance() const override SIP_FACTORY;
+
+  protected:
+    bool prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback * ) override;
+    QVariantMap processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
+
+  private:
+    std::unique_ptr< QgsFeatureSource > mSource;
+    std::unique_ptr< QgsFeatureSource > mDestination;
+    long long mKNeighbors = 1;
+    double mMaxDistance = 0.0;
+
+
 };
 
 #endif // QGSALGORITHMSHORTESTLINE_H