[FEATURE][processing] New 'assign projection' algorithm

This algorithm assigns a new projection to a vector layer.
It creates a new layer with the exact same features and
geometries as the input one, but assigned to a new CRS.
E.g. the geometries are not reprojected, they are just
assigned to a different CRS.

This algorithm can be used to repair layers which have
been assigned an incorrect projection.

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

@@ -0,0 +1,77 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ogr:FeatureCollection
+     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+     xsi:schemaLocation="http://ogr.maptools.org/ assign_projection.xsd"
+     xmlns:ogr="http://ogr.maptools.org/"
+     xmlns:gml="http://www.opengis.net/gml">
+  <gml:boundedBy>
+    <gml:Box>
+      <gml:coord><gml:X>0</gml:X><gml:Y>-5</gml:Y></gml:coord>
+      <gml:coord><gml:X>8</gml:X><gml:Y>3</gml:Y></gml:coord>
+    </gml:Box>
+  </gml:boundedBy>
+                                                                                                                                                               
+  <gml:featureMember>
+    <ogr:assign_projection fid="points.0">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4283"><gml:coordinates>1,1</gml:coordinates></gml:Point></ogr:geometryProperty>
+      <ogr:id>1</ogr:id>
+      <ogr:id2>2</ogr:id2>
+    </ogr:assign_projection>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:assign_projection fid="points.1">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4283"><gml:coordinates>3,3</gml:coordinates></gml:Point></ogr:geometryProperty>
+      <ogr:id>2</ogr:id>
+      <ogr:id2>1</ogr:id2>
+    </ogr:assign_projection>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:assign_projection fid="points.2">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4283"><gml:coordinates>2,2</gml:coordinates></gml:Point></ogr:geometryProperty>
+      <ogr:id>3</ogr:id>
+      <ogr:id2>0</ogr:id2>
+    </ogr:assign_projection>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:assign_projection fid="points.3">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4283"><gml:coordinates>5,2</gml:coordinates></gml:Point></ogr:geometryProperty>
+      <ogr:id>4</ogr:id>
+      <ogr:id2>2</ogr:id2>
+    </ogr:assign_projection>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:assign_projection fid="points.4">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4283"><gml:coordinates>4,1</gml:coordinates></gml:Point></ogr:geometryProperty>
+      <ogr:id>5</ogr:id>
+      <ogr:id2>1</ogr:id2>
+    </ogr:assign_projection>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:assign_projection fid="points.5">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4283"><gml:coordinates>0,-5</gml:coordinates></gml:Point></ogr:geometryProperty>
+      <ogr:id>6</ogr:id>
+      <ogr:id2>0</ogr:id2>
+    </ogr:assign_projection>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:assign_projection fid="points.6">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4283"><gml:coordinates>8,-1</gml:coordinates></gml:Point></ogr:geometryProperty>
+      <ogr:id>7</ogr:id>
+      <ogr:id2>0</ogr:id2>
+    </ogr:assign_projection>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:assign_projection fid="points.7">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4283"><gml:coordinates>7,-1</gml:coordinates></gml:Point></ogr:geometryProperty>
+      <ogr:id>8</ogr:id>
+      <ogr:id2>0</ogr:id2>
+    </ogr:assign_projection>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:assign_projection fid="points.8">
+      <ogr:geometryProperty><gml:Point srsName="EPSG:4283"><gml:coordinates>0,-1</gml:coordinates></gml:Point></ogr:geometryProperty>
+      <ogr:id>9</ogr:id>
+      <ogr:id2>0</ogr:id2>
+    </ogr:assign_projection>
+  </gml:featureMember>
+</ogr:FeatureCollection>

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

@@ -0,0 +1,37 @@
+<?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="assign_projection" type="ogr:assign_projection_Type" substitutionGroup="gml:_Feature"/>
+<xs:complexType name="assign_projection_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="id" nillable="true" minOccurs="0" maxOccurs="1">
+          <xs:simpleType>
+            <xs:restriction base="xs:long">
+              <xs:totalDigits value="10"/>
+            </xs:restriction>
+          </xs:simpleType>
+        </xs:element>
+        <xs:element name="id2" nillable="true" minOccurs="0" maxOccurs="1">
+          <xs:simpleType>
+            <xs:restriction base="xs:long">
+              <xs:totalDigits value="10"/>
+            </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

@@ -4148,3 +4148,15 @@ tests:
       OUTPUT:
         name: expected/extract_by_extent_clip.gml
         type: vector
+
+  - algorithm: native:assignprojection
+    name: Assign projection
+    params:
+      CRS: EPSG:4283
+      INPUT:
+        name: custom/points.shp
+        type: vector
+    results:
+      OUTPUT:
+        name: expected/assign_projection.gml
+        type: vector

src/core/processing/qgsnativealgorithms.cpp

@@ -92,6 +92,7 @@ void QgsNativeAlgorithms::loadAlgorithms()
   addAlgorithm( new QgsRasterLayerUniqueValuesReportAlgorithm() );
   addAlgorithm( new QgsJoinByAttributeAlgorithm() );
   addAlgorithm( new QgsJoinWithLinesAlgorithm() );
+  addAlgorithm( new QgsAssignProjectionAlgorithm() );
 }
 
 void QgsSaveSelectedFeatures::initAlgorithm( const QVariantMap & )
@@ -666,6 +667,37 @@ QgsFeature QgsTransformAlgorithm::processFeature( const QgsFeature &f, QgsProces
 }
 
 
+QString QgsAssignProjectionAlgorithm::shortHelpString() const
+{
+  return QObject::tr( "This algorithm assigns a new projection to a vector layer. It creates a new layer with the exact same features "
+                      "and geometries as the input one, but assigned to a new CRS. E.g. the geometries are not reprojected, they are just assigned "
+                      "to a different CRS. This algorithm can be used to repair layers which have been assigned an incorrect projection.\n\n"
+                      "Attributes are not modified by this algorithm." );
+}
+
+QgsAssignProjectionAlgorithm *QgsAssignProjectionAlgorithm::createInstance() const
+{
+  return new QgsAssignProjectionAlgorithm();
+}
+
+void QgsAssignProjectionAlgorithm::initParameters( const QVariantMap & )
+{
+  addParameter( new QgsProcessingParameterCrs( QStringLiteral( "CRS" ), QObject::tr( "Assigned CRS" ), QStringLiteral( "EPSG:4326" ) ) );
+}
+
+bool QgsAssignProjectionAlgorithm::prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback * )
+{
+  mDestCrs = parameterAsCrs( parameters, QStringLiteral( "CRS" ), context );
+  return true;
+}
+
+QgsFeature QgsAssignProjectionAlgorithm::processFeature( const QgsFeature &feature, QgsProcessingFeedback * )
+{
+  return feature;
+}
+
+
+
 void QgsSubdivideAlgorithm::initParameters( const QVariantMap & )
 {
   addParameter( new QgsProcessingParameterNumber( QStringLiteral( "MAX_NODES" ), QObject::tr( "Maximum nodes in parts" ), QgsProcessingParameterNumber::Integer,

src/core/processing/qgsnativealgorithms.h

@@ -131,6 +131,39 @@ class QgsTransformAlgorithm : public QgsProcessingFeatureBasedAlgorithm
 
 };
 
+
+
+/**
+ * Native assign projection algorithm.
+ */
+class QgsAssignProjectionAlgorithm : public QgsProcessingFeatureBasedAlgorithm
+{
+
+  public:
+
+    QgsAssignProjectionAlgorithm() = default;
+    QString name() const override { return QStringLiteral( "assignprojection" ); }
+    QString displayName() const override { return QObject::tr( "Assign projection" ); }
+    virtual QStringList tags() const override { return QObject::tr( "assign,set,transform,reproject,crs,srs,warp" ).split( ',' ); }
+    QString group() const override { return QObject::tr( "Vector general" ); }
+    QString shortHelpString() const override;
+    QgsAssignProjectionAlgorithm *createInstance() const override SIP_FACTORY;
+
+  protected:
+
+    void initParameters( const QVariantMap &configuration = QVariantMap() ) override;
+    QgsCoordinateReferenceSystem outputCrs( const QgsCoordinateReferenceSystem & ) const override { return mDestCrs; }
+    QString outputName() const override { return QObject::tr( "Assigned CRS" ); }
+
+    bool prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
+    QgsFeature processFeature( const QgsFeature &feature, QgsProcessingFeedback *feedback ) override;
+
+  private:
+
+    QgsCoordinateReferenceSystem mDestCrs;
+
+};
+
 /**
  * Native buffer algorithm.
  */