[FEATURE] New processing algorithm "extract/clip by extent"

Allows extract a subset of another layer using an extent, with
optional setting to clip geometries to the extent

python/plugins/processing/tests/testdata/expected/extract_by_extent.gfs

@@ -0,0 +1,33 @@
+<GMLFeatureClassList>
+  <GMLFeatureClass>
+    <Name>extract_by_extent</Name>
+    <ElementPath>extract_by_extent</ElementPath>
+    <!--POLYGON-->
+    <GeometryType>3</GeometryType>
+    <SRSName>EPSG:4326</SRSName>
+    <DatasetSpecificInfo>
+      <FeatureCount>3</FeatureCount>
+      <ExtentXMin>-1.00000</ExtentXMin>
+      <ExtentXMax>10.00000</ExtentXMax>
+      <ExtentYMin>-3.00000</ExtentYMin>
+      <ExtentYMax>3.00000</ExtentYMax>
+    </DatasetSpecificInfo>
+    <PropertyDefn>
+      <Name>name</Name>
+      <ElementPath>name</ElementPath>
+      <Type>String</Type>
+      <Width>5</Width>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>intval</Name>
+      <ElementPath>intval</ElementPath>
+      <Type>Integer</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>floatval</Name>
+      <ElementPath>floatval</ElementPath>
+      <Type>String</Type>
+      <Width>18</Width>
+    </PropertyDefn>
+  </GMLFeatureClass>
+</GMLFeatureClassList>

python/plugins/processing/tests/testdata/expected/extract_by_extent.gml

@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ogr:FeatureCollection
+     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+     xsi:schemaLocation=""
+     xmlns:ogr="http://ogr.maptools.org/"
+     xmlns:gml="http://www.opengis.net/gml">
+  <gml:boundedBy>
+    <gml:Box>
+      <gml:coord><gml:X>-1</gml:X><gml:Y>-3</gml:Y></gml:coord>
+      <gml:coord><gml:X>6</gml:X><gml:Y>3</gml:Y></gml:coord>
+    </gml:Box>
+  </gml:boundedBy>
+                                                                                                                                                        
+  <gml:featureMember>
+    <ogr:extract_by_extent fid="polys.0">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>-1,-1 -1,3 3,3 3,2 2,2 2,-1 -1,-1</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+      <ogr:name>aaaaa</ogr:name>
+      <ogr:intval>33</ogr:intval>
+      <ogr:floatval>44.123456</ogr:floatval>
+    </ogr:extract_by_extent>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:extract_by_extent fid="polys.5">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>3,2 6,1 6,-3 2,-1 2,2 3,2</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+      <ogr:name>elim</ogr:name>
+      <ogr:intval>2</ogr:intval>
+      <ogr:floatval>3.33</ogr:floatval>
+    </ogr:extract_by_extent>
+  </gml:featureMember>
+</ogr:FeatureCollection>

python/plugins/processing/tests/testdata/expected/extract_by_extent_clip.gfs

@@ -0,0 +1,32 @@
+<GMLFeatureClassList>
+  <GMLFeatureClass>
+    <Name>extract_by_extent_clip</Name>
+    <ElementPath>extract_by_extent_clip</ElementPath>
+    <!--MULTIPOLYGON-->
+    <GeometryType>6</GeometryType>
+    <SRSName>EPSG:4326</SRSName>
+    <DatasetSpecificInfo>
+      <FeatureCount>2</FeatureCount>
+      <ExtentXMin>-1.00000</ExtentXMin>
+      <ExtentXMax>4.77500</ExtentXMax>
+      <ExtentYMin>-2.38750</ExtentYMin>
+      <ExtentYMax>3.00000</ExtentYMax>
+    </DatasetSpecificInfo>
+    <PropertyDefn>
+      <Name>name</Name>
+      <ElementPath>name</ElementPath>
+      <Type>String</Type>
+      <Width>5</Width>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>intval</Name>
+      <ElementPath>intval</ElementPath>
+      <Type>Integer</Type>
+    </PropertyDefn>
+    <PropertyDefn>
+      <Name>floatval</Name>
+      <ElementPath>floatval</ElementPath>
+      <Type>Real</Type>
+    </PropertyDefn>
+  </GMLFeatureClass>
+</GMLFeatureClassList>

python/plugins/processing/tests/testdata/expected/extract_by_extent_clip.gml

@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ogr:FeatureCollection
+     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+     xsi:schemaLocation=""
+     xmlns:ogr="http://ogr.maptools.org/"
+     xmlns:gml="http://www.opengis.net/gml">
+  <gml:boundedBy>
+    <gml:Box>
+      <gml:coord><gml:X>-1</gml:X><gml:Y>-2.3875</gml:Y></gml:coord>
+      <gml:coord><gml:X>4.775</gml:X><gml:Y>3</gml:Y></gml:coord>
+    </gml:Box>
+  </gml:boundedBy>
+                                                                                                                                               
+  <gml:featureMember>
+    <ogr:extract_by_extent_clip fid="polys.0">
+      <ogr:geometryProperty><gml:MultiPolygon srsName="EPSG:4326"><gml:polygonMember><gml:Polygon><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>-1,-1 -1,3 3,3 3,2 2,2 2,-1 -1,-1</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></gml:polygonMember></gml:MultiPolygon></ogr:geometryProperty>
+      <ogr:name>aaaaa</ogr:name>
+      <ogr:intval>33</ogr:intval>
+      <ogr:floatval>44.123456</ogr:floatval>
+    </ogr:extract_by_extent_clip>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:extract_by_extent_clip fid="polys.5">
+      <ogr:geometryProperty><gml:MultiPolygon srsName="EPSG:4326"><gml:polygonMember><gml:Polygon><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>3,2 4.775,1.40833333333333 4.775,-2.3875 2,-1 2,2 3,2</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></gml:polygonMember></gml:MultiPolygon></ogr:geometryProperty>
+      <ogr:name>elim</ogr:name>
+      <ogr:intval>2</ogr:intval>
+      <ogr:floatval>3.33</ogr:floatval>
+    </ogr:extract_by_extent_clip>
+  </gml:featureMember>
+</ogr:FeatureCollection>

python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml

@@ -3937,4 +3937,30 @@ tests:
         - name
         compare:
           fields:
-            fid: skip
+            fid: skip
+
+  - algorithm: native:extractbyextent
+    name: Extract by extent
+    params:
+      CLIP: false
+      EXTENT: -1.1650000000000003,4.775,-2.444285714285715,3.4171428571428573
+      INPUT:
+        name: polys.gml
+        type: vector
+    results:
+      OUTPUT:
+        name: expected/extract_by_extent.gml
+        type: vector
+
+  - algorithm: native:extractbyextent
+    name: Extract by extent (clipped)
+    params:
+      CLIP: true
+      EXTENT: -1.1650000000000003,4.775,-2.444285714285715,3.4171428571428573
+      INPUT:
+        name: polys.gml
+        type: vector
+    results:
+      OUTPUT:
+        name: expected/extract_by_extent_clip.gml
+        type: vector

src/core/processing/qgsnativealgorithms.cpp

@@ -82,6 +82,7 @@ void QgsNativeAlgorithms::loadAlgorithms()
   addAlgorithm( new QgsMergeLinesAlgorithm() );
   addAlgorithm( new QgsSmoothAlgorithm() );
   addAlgorithm( new QgsSimplifyAlgorithm() );
+  addAlgorithm( new QgsExtractByExtentAlgorithm() );
 }
 
 void QgsCentroidAlgorithm::initAlgorithm( const QVariantMap & )
@@ -1811,7 +1812,77 @@ QgsFeature QgsSimplifyAlgorithm::processFeature( const QgsFeature &feature, QgsP
   return f;
 }
 
+
+
+
+void QgsExtractByExtentAlgorithm::initAlgorithm( const QVariantMap & )
+{
+  addParameter( new QgsProcessingParameterFeatureSource( QStringLiteral( "INPUT" ), QObject::tr( "Input layer" ) ) );
+  addParameter( new QgsProcessingParameterExtent( QStringLiteral( "EXTENT" ), QObject::tr( "Extent" ) ) );
+  addParameter( new QgsProcessingParameterBoolean( QStringLiteral( "CLIP" ), QObject::tr( "Clip features to extent" ), false ) );
+  addParameter( new QgsProcessingParameterFeatureSink( QStringLiteral( "OUTPUT" ), QObject::tr( "Extracted" ) ) );
+}
+
+QString QgsExtractByExtentAlgorithm::shortHelpString() const
+{
+  return QObject::tr( "This algorithm creates a new vector layer that only contains features which fall within a specified extent. "
+                      "Any features which intersect the extent will be included.\n\n"
+                      "Optionally, feature geometries can also be clipped to the extent. If this option is selected, then the output "
+                      "geometries will automatically be converted to multi geometries to ensure uniform output geometry types." );
+}
+
+QgsExtractByExtentAlgorithm *QgsExtractByExtentAlgorithm::createInstance() const
+{
+  return new QgsExtractByExtentAlgorithm();
+}
+
+QVariantMap QgsExtractByExtentAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
+{
+  std::unique_ptr< QgsFeatureSource > featureSource( parameterAsSource( parameters, QStringLiteral( "INPUT" ), context ) );
+  if ( !featureSource )
+    return QVariantMap();
+
+  QgsRectangle extent = parameterAsExtent( parameters, QStringLiteral( "EXTENT" ), context );
+  bool clip = parameterAsBool( parameters, QStringLiteral( "CLIP" ), context );
+
+  // if clipping, we force multi output
+  QgsWkbTypes::Type outType = clip ? QgsWkbTypes::multiType( featureSource->wkbType() ) : featureSource->wkbType();
+
+  QString dest;
+  std::unique_ptr< QgsFeatureSink > sink( parameterAsSink( parameters, QStringLiteral( "OUTPUT" ), context, dest, featureSource->fields(), outType, featureSource->sourceCrs() ) );
+
+  if ( !sink )
+    return QVariantMap();
+
+  QgsGeometry clipGeom = QgsGeometry::fromRect( extent );
+
+  double step = featureSource->featureCount() > 0 ? 100.0 / featureSource->featureCount() : 1;
+  QgsFeatureIterator inputIt = featureSource->getFeatures( QgsFeatureRequest().setFilterRect( extent ).setFlags( QgsFeatureRequest::ExactIntersect ) );
+  QgsFeature f;
+  int i = -1;
+  while ( inputIt.nextFeature( f ) )
+  {
+    i++;
+    if ( feedback->isCanceled() )
+    {
+      break;
+    }
+
+    if ( clip )
+    {
+      QgsGeometry g = f.geometry().intersection( clipGeom );
+      g.convertToMultiType();
+      f.setGeometry( g );
+    }
+
+    sink->addFeature( f, QgsFeatureSink::FastInsert );
+    feedback->setProgress( i * step );
+  }
+
+  QVariantMap outputs;
+  outputs.insert( QStringLiteral( "OUTPUT" ), dest );
+  return outputs;
+}
+
 ///@endcond
 
-
-

src/core/processing/qgsnativealgorithms.h

@@ -662,6 +662,32 @@ class QgsSimplifyAlgorithm : public QgsProcessingFeatureBasedAlgorithm
     std::unique_ptr< QgsMapToPixelSimplifier > mSimplifier;
 
 };
+
+
+/**
+ * Native extract/clip by extent algorithm.
+ */
+class QgsExtractByExtentAlgorithm : public QgsProcessingAlgorithm
+{
+
+  public:
+
+    QgsExtractByExtentAlgorithm() = default;
+    void initAlgorithm( const QVariantMap &configuration = QVariantMap() ) override;
+    QString name() const override { return QStringLiteral( "extractbyextent" ); }
+    QString displayName() const override { return QObject::tr( "Extract/clip by extent" ); }
+    virtual QStringList tags() const override { return QObject::tr( "clip,extract,intersect,intersection,mask,extent" ).split( ',' ); }
+    QString group() const override { return QObject::tr( "Vector overlay" ); }
+    QString shortHelpString() const override;
+    QgsExtractByExtentAlgorithm *createInstance() const override SIP_FACTORY;
+
+  protected:
+
+    virtual QVariantMap processAlgorithm( const QVariantMap &parameters,
+                                          QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
+
+};
+
 ///@endcond PRIVATE
 
 #endif // QGSNATIVEALGORITHMS_H