[FEATURE][processing] Add algorithm to swap x/y coordinate values

This algorithm swaps the X and Y coordinate values in input
geometries. It can be used to repair geometries which have
accidentally had their latitude and longitude values reversed.

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

@@ -0,0 +1,58 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ogr:FeatureCollection
+     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+     xsi:schemaLocation="http://ogr.maptools.org/ swap_xy.xsd"
+     xmlns:ogr="http://ogr.maptools.org/"
+     xmlns:gml="http://www.opengis.net/gml">
+  <gml:boundedBy>
+    <gml:Box>
+      <gml:coord><gml:X>-3</gml:X><gml:Y>-1</gml:Y></gml:coord>
+      <gml:coord><gml:X>6</gml:X><gml:Y>10</gml:Y></gml:coord>
+    </gml:Box>
+  </gml:boundedBy>
+
+  <gml:featureMember>
+    <ogr:swap_xy fid="polys.0">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>-1,-1 3,-1 3,3 2,3 2,2 -1,2 -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:swap_xy>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:swap_xy fid="polys.1">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>5,5 4,6 4,4 5,5</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+      <ogr:name>Aaaaa</ogr:name>
+      <ogr:intval>-33</ogr:intval>
+      <ogr:floatval>0</ogr:floatval>
+    </ogr:swap_xy>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:swap_xy fid="polys.2">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>5,2 6,2 6,3 5,3 5,2</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+      <ogr:name>bbaaa</ogr:name>
+      <ogr:floatval>0.123</ogr:floatval>
+    </ogr:swap_xy>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:swap_xy fid="polys.3">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>1,6 1,10 -3,10 -3,6 1,6</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs><gml:innerBoundaryIs><gml:LinearRing><gml:coordinates>0,7 -2,7 -2,9 0,9 0,7</gml:coordinates></gml:LinearRing></gml:innerBoundaryIs></gml:Polygon></ogr:geometryProperty>
+      <ogr:name>ASDF</ogr:name>
+      <ogr:intval>0</ogr:intval>
+    </ogr:swap_xy>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:swap_xy fid="polys.4">
+      <ogr:intval>120</ogr:intval>
+      <ogr:floatval>-100291.43213</ogr:floatval>
+    </ogr:swap_xy>
+  </gml:featureMember>
+  <gml:featureMember>
+    <ogr:swap_xy fid="polys.5">
+      <ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>2,3 1,6 -3,6 -1,2 2,2 2,3</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:swap_xy>
+  </gml:featureMember>
+</ogr:FeatureCollection>

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

@@ -0,0 +1,43 @@
+<?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="swap_xy" type="ogr:swap_xy_Type" substitutionGroup="gml:_Feature"/>
+<xs:complexType name="swap_xy_Type">
+  <xs:complexContent>
+    <xs:extension base="gml:AbstractFeatureType">
+      <xs:sequence>
+        <xs:element name="geometryProperty" type="gml:PolygonPropertyType" nillable="true" minOccurs="0" maxOccurs="1"/>
+        <xs:element name="name" nillable="true" minOccurs="0" maxOccurs="1">
+          <xs:simpleType>
+            <xs:restriction base="xs:string">
+              <xs:maxLength value="5"/>
+            </xs:restriction>
+          </xs:simpleType>
+        </xs:element>
+        <xs:element name="intval" 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="floatval" nillable="true" minOccurs="0" maxOccurs="1">
+          <xs:simpleType>
+            <xs:restriction base="xs:decimal">
+            </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

@@ -4944,3 +4944,14 @@ tests:
       OUTPUT:
         name: expected/concave_hull_points_07.gml
         type: vector
+
+  - algorithm: native:swapxy
+    name: Swap XY coordinates
+    params:
+      INPUT:
+        name: polys.gml
+        type: vector
+    results:
+      OUTPUT:
+        name: expected/swap_xy.gml
+        type: vector

src/analysis/CMakeLists.txt

@@ -68,6 +68,7 @@ SET(QGIS_ANALYSIS_SRCS
   processing/qgsalgorithmsnaptogrid.cpp
   processing/qgsalgorithmsplitwithlines.cpp
   processing/qgsalgorithmstringconcatenation.cpp
+  processing/qgsalgorithmswapxy.cpp
   processing/qgsalgorithmsubdivide.cpp
   processing/qgsalgorithmtransect.cpp
   processing/qgsalgorithmtransform.cpp

src/analysis/processing/qgsalgorithmswapxy.cpp

@@ -0,0 +1,82 @@
+/***************************************************************************
+                         qgsalgorithmswapxy.cpp
+                         ------------------------
+    begin                : April 2018
+    copyright            : (C) 2018 by Nyall Dawson
+    email                : nyall dot dawson 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.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#include "qgsalgorithmswapxy.h"
+
+///@cond PRIVATE
+
+QString QgsSwapXYAlgorithm::name() const
+{
+  return QStringLiteral( "swapxy" );
+}
+
+QString QgsSwapXYAlgorithm::displayName() const
+{
+  return QObject::tr( "Swap X and Y coordinates" );
+}
+
+QStringList QgsSwapXYAlgorithm::tags() const
+{
+  return QObject::tr( "invert,flip,swap,latitude,longitude" ).split( ',' );
+}
+
+QString QgsSwapXYAlgorithm::group() const
+{
+  return QObject::tr( "Vector geometry" );
+}
+
+QString QgsSwapXYAlgorithm::groupId() const
+{
+  return QStringLiteral( "vectorgeometry" );
+}
+
+QString QgsSwapXYAlgorithm::outputName() const
+{
+  return QObject::tr( "Swapped" );
+}
+
+QString QgsSwapXYAlgorithm::shortHelpString() const
+{
+  return QObject::tr( "This algorithm swaps the X and Y coordinate values in input geometries. It can be used to repair geometries "
+                      "which have accidentally had their latitude and longitude values reversed." );
+}
+
+QgsSwapXYAlgorithm *QgsSwapXYAlgorithm::createInstance() const
+{
+  return new QgsSwapXYAlgorithm();
+}
+
+QgsFeatureList QgsSwapXYAlgorithm::processFeature( const QgsFeature &f, QgsProcessingContext &, QgsProcessingFeedback * )
+{
+  QgsFeatureList list;
+  QgsFeature feature = f;
+  if ( feature.hasGeometry() )
+  {
+    QgsGeometry geom = feature.geometry();
+    std::unique_ptr< QgsAbstractGeometry > swappedGeom( geom.constGet()->clone() );
+    swappedGeom->swapXy();
+    feature.setGeometry( QgsGeometry( std::move( swappedGeom ) ) );
+    list << feature;
+  }
+  else
+  {
+    list << feature;
+  }
+  return list;
+}
+
+///@endcond

src/analysis/processing/qgsalgorithmswapxy.h

@@ -0,0 +1,56 @@
+/***************************************************************************
+                         qgsalgorithmswapxy.h
+                         ----------------------
+    begin                : April 2018
+    copyright            : (C) 2018 by Nyall Dawson
+    email                : nyall dot dawson 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.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#ifndef QGSALGORITHMSWAPXY_H
+#define QGSALGORITHMSWAPXY_H
+
+#define SIP_NO_FILE
+
+#include "qgis.h"
+#include "qgsprocessingalgorithm.h"
+
+///@cond PRIVATE
+
+/**
+ * Native swap x-y coordinates algorithm.
+ */
+class QgsSwapXYAlgorithm : public QgsProcessingFeatureBasedAlgorithm
+{
+
+  public:
+
+    QgsSwapXYAlgorithm() = default;
+    QString name() const override;
+    QString displayName() const override;
+    QStringList tags() const override;
+    QString group() const override;
+    QString groupId() const override;
+    QString shortHelpString() const override;
+    QgsSwapXYAlgorithm *createInstance() const override SIP_FACTORY;
+
+  protected:
+
+    QString outputName() const override;
+    QgsFeatureList processFeature( const QgsFeature &feature,  QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
+
+};
+
+///@endcond PRIVATE
+
+#endif // QGSALGORITHMSWAPXY_H
+
+

src/analysis/processing/qgsnativealgorithms.cpp

@@ -66,6 +66,7 @@
 #include "qgsalgorithmsplitwithlines.h"
 #include "qgsalgorithmstringconcatenation.h"
 #include "qgsalgorithmsubdivide.h"
+#include "qgsalgorithmswapxy.h"
 #include "qgsalgorithmtransect.h"
 #include "qgsalgorithmtransform.h"
 #include "qgsalgorithmtranslate.h"
@@ -164,6 +165,7 @@ void QgsNativeAlgorithms::loadAlgorithms()
   addAlgorithm( new QgsSplitWithLinesAlgorithm() );
   addAlgorithm( new QgsStringConcatenationAlgorithm() );
   addAlgorithm( new QgsSubdivideAlgorithm() );
+  addAlgorithm( new QgsSwapXYAlgorithm() );
   addAlgorithm( new QgsTransectAlgorithm() );
   addAlgorithm( new QgsTransformAlgorithm() );
   addAlgorithm( new QgsTranslateAlgorithm() );