[FEATURE][processing] allow to create points on all parts in point on…

… surface alg

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

@@ -0,0 +1,46 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ogr:FeatureCollection
+     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+     xsi:schemaLocation="http://ogr.maptools.org/ point_on_multipoly.xsd"
+     xmlns:ogr="http://ogr.maptools.org/"
+     xmlns:gml="http://www.opengis.net/gml">
+  <gml:boundedBy>
+    <gml:Box>
+      <gml:coord><gml:X>0.5</gml:X><gml:Y>0.5</gml:Y></gml:coord>
+      <gml:coord><gml:X>8</gml:X><gml:Y>5.5</gml:Y></gml:coord>
+    </gml:Box>
+  </gml:boundedBy>
+
+  <gml:featureMember>
+    <ogr:point_on_multipoly fid="multipolys.0">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4326"><gml:coordinates>3.5,2.5</gml:coordinates></gml:Point></ogr:geometryProperty>
+      <ogr:Bname>Test</ogr:Bname>
+      <ogr:Bintval>1</ogr:Bintval>
+      <ogr:Bfloatval>0.12300</ogr:Bfloatval>
+    </ogr:point_on_multipoly>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:point_on_multipoly fid="multipolys.1">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4326"><gml:coordinates>7.5,1.0</gml:coordinates></gml:Point></ogr:geometryProperty>
+      <ogr:Bname xsi:nil="true"/>
+      <ogr:Bintval xsi:nil="true"/>
+      <ogr:Bfloatval xsi:nil="true"/>
+    </ogr:point_on_multipoly>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:point_on_multipoly fid="multipolys.1">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4326"><gml:coordinates>8.0,5.5</gml:coordinates></gml:Point></ogr:geometryProperty>
+      <ogr:Bname xsi:nil="true"/>
+      <ogr:Bintval xsi:nil="true"/>
+      <ogr:Bfloatval xsi:nil="true"/>
+    </ogr:point_on_multipoly>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:point_on_multipoly fid="multipolys.2">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4326"><gml:coordinates>0.5,0.5</gml:coordinates></gml:Point></ogr:geometryProperty>
+      <ogr:Bname>Test</ogr:Bname>
+      <ogr:Bintval>2</ogr:Bintval>
+      <ogr:Bfloatval>-0.12300</ogr:Bfloatval>
+    </ogr:point_on_multipoly>
+  </gml:featureMember>
+</ogr:FeatureCollection>

python/plugins/processing/tests/testdata/expected/point_on_multipoly.xsd

@@ -0,0 +1,45 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xs:schema targetNamespace="http://ogr.maptools.org/" xmlns:ogr="http://ogr.maptools.org/" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:gml="http://www.opengis.net/gml" elementFormDefault="qualified" version="1.0">
+<xs:import namespace="http://www.opengis.net/gml" schemaLocation="http://schemas.opengis.net/gml/2.1.2/feature.xsd"/>
+<xs:element name="FeatureCollection" type="ogr:FeatureCollectionType" substitutionGroup="gml:_FeatureCollection"/>
+<xs:complexType name="FeatureCollectionType">
+  <xs:complexContent>
+    <xs:extension base="gml:AbstractFeatureCollectionType">
+      <xs:attribute name="lockId" type="xs:string" use="optional"/>
+      <xs:attribute name="scope" type="xs:string" use="optional"/>
+    </xs:extension>
+  </xs:complexContent>
+</xs:complexType>
+<xs:element name="point_on_multipoly" type="ogr:point_on_multipoly_Type" substitutionGroup="gml:_Feature"/>
+<xs:complexType name="point_on_multipoly_Type">
+  <xs:complexContent>
+    <xs:extension base="gml:AbstractFeatureType">
+      <xs:sequence>
+        <xs:element name="geometryProperty" type="gml:PointPropertyType" nillable="true" minOccurs="0" maxOccurs="1"/>
+        <xs:element name="Bname" nillable="true" minOccurs="0" maxOccurs="1">
+          <xs:simpleType>
+            <xs:restriction base="xs:string">
+              <xs:maxLength value="4"/>
+            </xs:restriction>
+          </xs:simpleType>
+        </xs:element>
+        <xs:element name="Bintval" nillable="true" minOccurs="0" maxOccurs="1">
+          <xs:simpleType>
+            <xs:restriction base="xs:integer">
+              <xs:totalDigits value="10"/>
+            </xs:restriction>
+          </xs:simpleType>
+        </xs:element>
+        <xs:element name="Bfloatval" nillable="true" minOccurs="0" maxOccurs="1">
+          <xs:simpleType>
+            <xs:restriction base="xs:decimal">
+              <xs:totalDigits value="21"/>
+              <xs:fractionDigits value="5"/>
+            </xs:restriction>
+          </xs:simpleType>
+        </xs:element>
+      </xs:sequence>
+    </xs:extension>
+  </xs:complexContent>
+</xs:complexType>
+</xs:schema>

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

@@ -881,6 +881,18 @@ tests:
         name: expected/point_on_poly.gml
         type: vector
 
+  - algorithm: native:pointonsurface
+    name: Point on all parts of multi polygon surface
+    params:
+      INPUT:
+        name: multipolys.gml
+        type: vector
+      ALL_PARTS: true
+    results:
+      OUTPUT:
+        name: expected/point_on_multipoly.gml
+        type: vector
+
   - algorithm: qgis:pointonsurface
     name: Point on multipoint surface
     params:

src/analysis/processing/qgsalgorithmpointonsurface.cpp

@@ -16,6 +16,7 @@
  ***************************************************************************/
 
 #include "qgsalgorithmpointonsurface.h"
+#include "qgsgeometrycollection.h"
 
 ///@cond PRIVATE
 
@@ -59,19 +60,72 @@ QgsPointOnSurfaceAlgorithm *QgsPointOnSurfaceAlgorithm::createInstance() const
   return new QgsPointOnSurfaceAlgorithm();
 }
 
-QgsFeatureList QgsPointOnSurfaceAlgorithm::processFeature( const QgsFeature &f, QgsProcessingContext &, QgsProcessingFeedback *feedback )
+void QgsPointOnSurfaceAlgorithm::initParameters( const QVariantMap & )
 {
+  std::unique_ptr< QgsProcessingParameterBoolean> allParts = qgis::make_unique< QgsProcessingParameterBoolean >(
+        QStringLiteral( "ALL_PARTS" ),
+        QObject::tr( "Create point on surface for each part" ),
+        false );
+  allParts->setIsDynamic( true );
+  allParts->setDynamicPropertyDefinition( QgsPropertyDefinition( QStringLiteral( "All parts" ), QObject::tr( "Create point on surface for each part" ), QgsPropertyDefinition::Boolean ) );
+  allParts->setDynamicLayerParameterName( QStringLiteral( "INPUT" ) );
+  addParameter( allParts.release() );
+}
+
+bool QgsPointOnSurfaceAlgorithm::prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback * )
+{
+  mAllParts = parameterAsBool( parameters, QStringLiteral( "ALL_PARTS" ), context );
+  mDynamicAllParts = QgsProcessingParameters::isDynamic( parameters, QStringLiteral( "ALL_PARTS" ) );
+  if ( mDynamicAllParts )
+    mAllPartsProperty = parameters.value( QStringLiteral( "ALL_PARTS" ) ).value< QgsProperty >();
+
+  return true;
+}
+
+QgsFeatureList QgsPointOnSurfaceAlgorithm::processFeature( const QgsFeature &f, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
+{
+  QgsFeatureList list;
   QgsFeature feature = f;
   if ( feature.hasGeometry() )
   {
-    QgsGeometry outputGeometry = feature.geometry().pointOnSurface();
-    if ( !outputGeometry )
+    QgsGeometry geom = feature.geometry();
+
+    bool allParts = mAllParts;
+    if ( mDynamicAllParts )
+      allParts = mAllPartsProperty.valueAsBool( context.expressionContext(), allParts );
+
+    if ( allParts && geom.isMultipart() )
     {
-      feedback->pushInfo( QObject::tr( "Error calculating point on surface for feature %1: %2" ).arg( feature.id() ).arg( outputGeometry.lastError() ) );
+      const QgsGeometryCollection *geomCollection = static_cast<const QgsGeometryCollection *>( geom.constGet() );
+
+      for ( int i = 0; i < geomCollection->partCount(); ++i )
+      {
+        QgsGeometry partGeometry( geomCollection->geometryN( i )->clone() );
+        QgsGeometry outputGeometry = partGeometry.pointOnSurface();
+        if ( !outputGeometry )
+        {
+          feedback->pushInfo( QObject::tr( "Error calculating point on surface for feature %1 part %2: %3" ).arg( feature.id() ).arg( i ).arg( outputGeometry.lastError() ) );
+        }
+        feature.setGeometry( outputGeometry );
+        list << feature;
+      }
     }
-    feature.setGeometry( outputGeometry );
+    else
+    {
+      QgsGeometry outputGeometry = feature.geometry().pointOnSurface();
+      if ( !outputGeometry )
+      {
+        feedback->pushInfo( QObject::tr( "Error calculating point on surface for feature %1: %2" ).arg( feature.id() ).arg( outputGeometry.lastError() ) );
+      }
+      feature.setGeometry( outputGeometry );
+      list << feature;
+    }
+  }
+  else
+  {
+    list << feature;
   }
-  return QgsFeatureList() << feature;
+  return list;
 }
 
 ///@endcond

src/analysis/processing/qgsalgorithmpointonsurface.h

@@ -41,14 +41,23 @@ class QgsPointOnSurfaceAlgorithm : public QgsProcessingFeatureBasedAlgorithm
     QString groupId() const override;
     QString shortHelpString() const override;
     QgsPointOnSurfaceAlgorithm *createInstance() const override SIP_FACTORY;
+    void initParameters( const QVariantMap &configuration = QVariantMap() ) override;
 
   protected:
 
     QString outputName() const override;
     QgsProcessing::SourceType outputLayerType() const override { return QgsProcessing::TypeVectorPoint; }
     QgsWkbTypes::Type outputWkbType( QgsWkbTypes::Type inputWkbType ) const override { Q_UNUSED( inputWkbType ); return QgsWkbTypes::Point; }
 
+    bool prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
     QgsFeatureList processFeature( const QgsFeature &feature,  QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
+
+  private:
+
+    bool mAllParts = false;
+    bool mDynamicAllParts = false;
+    QgsProperty mAllPartsProperty;
+
 };
 
 ///@endcond PRIVATE