[FEATURE] Add feature filter algorithm

Adds a new "feature filter" algorithm. This algorithm takes a list of expressions and
creates an output for each of them. Matching features from the input layer are sent
to the outputs.

This allows for an algorithm to only handle a subset of incoming features or to send
different features to different outputs.

The algorithm is only available in the modeler.

python/core/core_auto.sip

@@ -367,6 +367,7 @@
 %Include locator/qgslocator.sip
 %Include locator/qgslocatorfilter.sip
 %Include locator/qgslocatormodel.sip
+%Include processing/qgsprocessingalgorithmconfigurationwidget.sip
 %Include processing/qgsprocessingalgrunnertask.sip
 %Include processing/qgsprocessingfeedback.sip
 %Include processing/qgsprocessingprovider.sip

python/core/processing/qgsprocessingalgorithmconfigurationwidget.sip.in

@@ -0,0 +1,31 @@
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/core/processing/qgsprocessingalgorithmconfigurationwidget.h      *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/
+
+
+
+
+class QgsProcessingAlgorithmConfigurationWidget : QWidget
+{
+
+%TypeHeaderCode
+#include "qgsprocessingalgorithmconfigurationwidget.h"
+%End
+  public:
+    QgsProcessingAlgorithmConfigurationWidget( QWidget *parent = 0 );
+    virtual ~QgsProcessingAlgorithmConfigurationWidget();
+    virtual QVariantMap configuration() const = 0;
+    virtual void setConfiguration( const QVariantMap &configuration ) = 0;
+};
+
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/core/processing/qgsprocessingalgorithmconfigurationwidget.h      *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/

src/analysis/CMakeLists.txt

@@ -38,6 +38,7 @@ SET(QGIS_ANALYSIS_SRCS
   processing/qgsalgorithmextractbylocation.cpp
   processing/qgsalgorithmextractvertices.cpp
   processing/qgsalgorithmfiledownloader.cpp
+  processing/qgsalgorithmfilter.cpp
   processing/qgsalgorithmfixgeometries.cpp
   processing/qgsalgorithmjoinbyattribute.cpp
   processing/qgsalgorithmjoinwithlines.cpp
@@ -139,6 +140,7 @@ SET(QGIS_ANALYSIS_MOC_HDRS
   network/qgsvectorlayerdirector.h
 
   processing/qgsalgorithmfiledownloader.h
+  processing/qgsalgorithmfilter.h
 
   vector/geometry_checker/qgsfeaturepool.h
   vector/geometry_checker/qgsgeometrychecker.h

src/analysis/processing/qgsalgorithmfilter.cpp

@@ -0,0 +1,247 @@
+/***************************************************************************
+                         qgsalgorithmfilter.cpp
+                         ---------------------
+    begin                : April 2018
+    copyright            : (C) 2018 by Matthias Kuhn
+    email                : matthias@opengis.ch
+ ***************************************************************************/
+
+/***************************************************************************
+ *                                                                         *
+ *   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 "qgsalgorithmfilter.h"
+#include "qgsapplication.h"
+
+#include <QLabel>
+#include <QGridLayout>
+#include <QTableWidget>
+#include <QHeaderView>
+#include <QToolButton>
+
+///@cond PRIVATE
+
+QString QgsFilterAlgorithm::name() const
+{
+  return QStringLiteral( "filter" );
+}
+
+QString QgsFilterAlgorithm::displayName() const
+{
+  return QObject::tr( "Filter" );
+}
+
+QStringList QgsFilterAlgorithm::tags() const
+{
+  return QObject::tr( "filter,proxy,redirect,route" ).split( ',' );
+}
+
+QString QgsFilterAlgorithm::group() const
+{
+  return QObject::tr( "Vector geometry" );
+}
+
+QString QgsFilterAlgorithm::groupId() const
+{
+  return QStringLiteral( "vectorgeometry" );
+}
+
+QgsProcessingAlgorithm::Flags QgsFilterAlgorithm::flags() const
+{
+  return FlagHideFromToolbox;
+}
+
+QString QgsFilterAlgorithm::shortHelpString() const
+{
+  return QObject::tr( "This algorithm filters features from the input layer and redirects them to one or several outputs." );
+}
+
+QgsFilterAlgorithm *QgsFilterAlgorithm::createInstance() const
+{
+  return new QgsFilterAlgorithm();
+}
+
+QgsProcessingAlgorithmConfigurationWidget *QgsFilterAlgorithm::createModelerWidget() const
+{
+  return new QgsFilterAlgorithmConfigurationWidget();
+}
+
+QgsFilterAlgorithm::~QgsFilterAlgorithm()
+{
+  qDeleteAll( mOutputs );
+}
+
+void QgsFilterAlgorithm::initAlgorithm( const QVariantMap &configuration )
+{
+  addParameter( new QgsProcessingParameterFeatureSource( QStringLiteral( "INPUT" ), QObject::tr( "Input layer" ) ) );
+
+  const QVariantList outputs = configuration.value( QStringLiteral( "outputs" ) ).toList();
+  for ( const QVariant &output : outputs )
+  {
+    const QVariantMap outputDef = output.toMap();
+    const QString name = QStringLiteral( "OUTPUT_%1" ).arg( outputDef.value( QStringLiteral( "name" ) ).toString() );
+    QgsProcessingParameterFeatureSink *outputParam = new QgsProcessingParameterFeatureSink( name, outputDef.value( QStringLiteral( "name" ) ).toString() );
+    outputParam->setFlags( QgsProcessingParameterDefinition::FlagHidden );
+    addParameter( outputParam );
+    mOutputs.append( new Output( name, outputDef.value( QStringLiteral( "expression" ) ).toString() ) );
+  }
+}
+
+
+QgsFilterAlgorithmConfigurationWidget::QgsFilterAlgorithmConfigurationWidget( QWidget *parent )
+  : QgsProcessingAlgorithmConfigurationWidget( parent )
+{
+  setContentsMargins( 0, 0, 0, 0 );
+
+  mOutputExpressionWidget = new QTableWidget();
+  mOutputExpressionWidget->setColumnCount( 2 );
+  mOutputExpressionWidget->setHorizontalHeaderItem( 0, new QTableWidgetItem( tr( "Output Name" ) ) );
+  mOutputExpressionWidget->setHorizontalHeaderItem( 1, new QTableWidgetItem( tr( "Filter Expression" ) ) );
+  mOutputExpressionWidget->horizontalHeader()->setStretchLastSection( true );
+  QGridLayout *layout = new QGridLayout();
+  setLayout( layout );
+
+  layout->addWidget( new QLabel( tr( "Outputs and filters" ) ), 0, 0, 1, 2 );
+  layout->addWidget( mOutputExpressionWidget, 1, 0, 4, 1 );
+  QToolButton *addOutputButton = new QToolButton();
+  addOutputButton->setIcon( QgsApplication::getThemeIcon( QStringLiteral( "/mActionAddLayer.svg" ) ) );
+  addOutputButton->setText( tr( "Add Output" ) );
+
+  QToolButton *removeOutputButton = new QToolButton();
+  removeOutputButton->setIcon( QgsApplication::getThemeIcon( QStringLiteral( "/mActionRemoveLayer.svg" ) ) );
+  removeOutputButton->setToolTip( tr( "Remove Selected Outputs" ) );
+
+  layout->addWidget( addOutputButton, 2, 1, 1, 1 );
+  layout->addWidget( removeOutputButton, 3, 1, 1, 1 );
+
+  connect( addOutputButton, &QToolButton::clicked, this, &QgsFilterAlgorithmConfigurationWidget::addOutput );
+  connect( removeOutputButton, &QToolButton::clicked, this, &QgsFilterAlgorithmConfigurationWidget::removeSelectedOutputs );
+
+  connect( mOutputExpressionWidget->selectionModel(), &QItemSelectionModel::selectionChanged, [removeOutputButton, this]
+  {
+    removeOutputButton->setEnabled( !mOutputExpressionWidget->selectionModel()->selectedIndexes().isEmpty() );
+  } );
+}
+
+QVariantMap QgsFilterAlgorithmConfigurationWidget::configuration() const
+{
+  QVariantList outputs;
+
+  for ( int i = 0; i < mOutputExpressionWidget->rowCount(); ++i )
+  {
+    QVariantMap output;
+    output.insert( QStringLiteral( "name" ), mOutputExpressionWidget->item( i, 0 )->text() );
+    output.insert( QStringLiteral( "expression" ), mOutputExpressionWidget->item( i, 1 )->text() );
+    outputs.append( output );
+  }
+
+  QVariantMap map;
+  map.insert( "outputs", outputs );
+
+  return map;
+}
+
+
+QVariantMap QgsFilterAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
+{
+  std::unique_ptr< QgsFeatureSource > source( parameterAsSource( parameters, QStringLiteral( "INPUT" ), context ) );
+  if ( !source )
+    return QVariantMap();
+
+  QgsExpressionContext expressionContext = context.expressionContext();
+  for ( Output *output : qgis::as_const( mOutputs ) )
+  {
+    output->sink.reset( parameterAsSink( parameters, output->name, context, output->destinationIdentifier, source->fields(), source->wkbType(), source->sourceCrs() ) );
+    output->expression.prepare( &expressionContext );
+  }
+
+  long count = source->featureCount();
+
+  QgsFeature f;
+  QgsFeatureIterator it = source->getFeatures();
+
+  double step = count > 0 ? 100.0 / count : 1;
+  int current = 0;
+
+  while ( it.nextFeature( f ) )
+  {
+    if ( feedback->isCanceled() )
+    {
+      break;
+    }
+
+    expressionContext.setFeature( f );
+
+    for ( Output *output : qgis::as_const( mOutputs ) )
+    {
+      if ( output->expression.evaluate( &expressionContext ).toBool() )
+        output->sink->addFeature( f, QgsFeatureSink::FastInsert );
+    }
+
+    feedback->setProgress( current * step );
+    current++;
+  }
+
+  QVariantMap outputs;
+  for ( const Output *output : qgis::as_const( mOutputs ) )
+  {
+    outputs.insert( output->name, output->destinationIdentifier );
+  }
+  return outputs;
+}
+
+
+void QgsFilterAlgorithmConfigurationWidget::setConfiguration( const QVariantMap &configuration )
+{
+  mOutputExpressionWidget->setRowCount( 0 );
+  int currentRow = 0;
+  const QVariantList outputs = configuration.value( "outputs" ).toList();
+
+  for ( const QVariant &outputvar : outputs )
+  {
+    const QVariantMap output = outputvar.toMap();
+    mOutputExpressionWidget->insertRow( currentRow );
+    mOutputExpressionWidget->setItem( currentRow, 0, new QTableWidgetItem( output.value( "name" ).toString() ) );
+    mOutputExpressionWidget->setItem( currentRow, 1, new QTableWidgetItem( output.value( "expression" ).toString() ) );
+
+    currentRow++;
+  }
+
+  if ( outputs.isEmpty() )
+    addOutput();
+}
+
+void QgsFilterAlgorithmConfigurationWidget::removeSelectedOutputs()
+{
+  QItemSelection selection( mOutputExpressionWidget->selectionModel()->selection() );
+
+  QList<int> rows;
+  const QModelIndexList indexes = selection.indexes();
+  for ( const QModelIndex &index : indexes )
+  {
+    rows.append( index.row() );
+  }
+
+  qSort( rows );
+
+  int prev = -1;
+  for ( int i = rows.count() - 1; i >= 0; i -= 1 )
+  {
+    int current = rows[i];
+    if ( current != prev )
+    {
+      mOutputExpressionWidget->removeRow( current );
+      prev = current;
+    }
+  }
+}
+
+void QgsFilterAlgorithmConfigurationWidget::addOutput()
+{
+  mOutputExpressionWidget->setRowCount( mOutputExpressionWidget->rowCount() + 1 );
+}