When exporting CRS information from GDAL >= 3.0, use WKT2 format

to avoid loss of CRS information

src/core/providers/gdal/qgsgdalprovider.cpp

@@ -293,6 +293,7 @@ QgsGdalProvider *QgsGdalProvider::clone() const
   return new QgsGdalProvider( *this );
 }
 
+#if GDAL_VERSION_NUM < GDAL_COMPUTE_VERSION(3,0,0)
 bool QgsGdalProvider::crsFromWkt( const char *wkt )
 {
 
@@ -330,6 +331,7 @@ bool QgsGdalProvider::crsFromWkt( const char *wkt )
 
   return mCrs.isValid();
 }
+#endif
 
 bool QgsGdalProvider::getCachedGdalHandles( QgsGdalProvider *provider,
     GDALDatasetH &gdalBaseDataset,
@@ -2716,10 +2718,30 @@ void QgsGdalProvider::initBaseDataset()
   // Get the layer's projection info and set up the
   // QgsCoordinateTransform for this layer
   // NOTE: we must do this before metadata is called
-
+#if GDAL_VERSION_NUM >= GDAL_COMPUTE_VERSION(3,0,0)
+  QString crsWkt;
+  if ( OGRSpatialReferenceH spatialRefSys = GDALGetSpatialRef( mGdalDataset ) )
+  {
+    crsWkt = QgsOgrUtils::OGRSpatialReferenceToWkt( spatialRefSys );
+  }
+  if ( crsWkt.isEmpty() )
+  {
+    if ( OGRSpatialReferenceH spatialRefSys = GDALGetGCPSpatialRef( mGdalDataset ) )
+    {
+      crsWkt = QgsOgrUtils::OGRSpatialReferenceToWkt( spatialRefSys );
+    }
+  }
+  if ( !crsWkt.isEmpty() )
+  {
+    mCrs = QgsCoordinateReferenceSystem::fromWkt( crsWkt );
+  }
+  else
+  {
+#else
   if ( !crsFromWkt( GDALGetProjectionRef( mGdalDataset ) ) &&
        !crsFromWkt( GDALGetGCPProjection( mGdalDataset ) ) )
   {
+#endif
     if ( mGdalBaseDataset != mGdalDataset &&
          GDALGetMetadata( mGdalBaseDataset, "RPC" ) )
     {

src/core/providers/gdal/qgsgdalprovider.h

@@ -239,8 +239,10 @@ class QgsGdalProvider : public QgsRasterDataProvider, QgsGdalProviderBase
     // update mode
     bool mUpdate;
 
+#if GDAL_VERSION_NUM < GDAL_COMPUTE_VERSION(3,0,0)
     // initialize CRS from wkt
     bool crsFromWkt( const char *wkt );
+#endif
 
     //! Do some initialization on the dataset (e.g. handling of south-up datasets)
     void initBaseDataset();

src/core/providers/ogr/qgsogrprovider.cpp

@@ -3698,20 +3698,9 @@ QgsCoordinateReferenceSystem QgsOgrProvider::crs() const
   // add towgs84 parameter
   QgsCoordinateReferenceSystem::setupESRIWktFix();
 
-  OGRSpatialReferenceH mySpatialRefSys = mOgrLayer->GetSpatialRef();
-  if ( mySpatialRefSys )
+  if ( OGRSpatialReferenceH spatialRefSys = mOgrLayer->GetSpatialRef() )
   {
-    // get the proj4 text
-    char *pszProj4 = nullptr;
-    OSRExportToProj4( mySpatialRefSys, &pszProj4 );
-    QgsDebugMsgLevel( pszProj4, 4 );
-    CPLFree( pszProj4 );
-
-    char *pszWkt = nullptr;
-    OSRExportToWkt( mySpatialRefSys, &pszWkt );
-
-    srs = QgsCoordinateReferenceSystem::fromWkt( pszWkt );
-    CPLFree( pszWkt );
+    srs = QgsOgrUtils::OGRSpatialReferenceToCrs( spatialRefSys );
   }
   else
   {

src/core/qgscoordinatereferencesystem.cpp

@@ -38,6 +38,7 @@
 #include "qgis.h" //const vals declared here
 #include "qgslocalec.h"
 #include "qgssettings.h"
+#include "qgsogrutils.h"
 
 #include <sqlite3.h>
 #if PROJ_VERSION_MAJOR>=6
@@ -335,7 +336,6 @@ bool QgsCoordinateReferenceSystem::createFromString( const QString &definition )
 bool QgsCoordinateReferenceSystem::createFromUserInput( const QString &definition )
 {
   QString userWkt;
-  char *wkt = nullptr;
   OGRSpatialReferenceH crs = OSRNewSpatialReference( nullptr );
 
   // make sure towgs84 parameter is loaded if using an ESRI definition and gdal >= 1.9
@@ -346,11 +346,7 @@ bool QgsCoordinateReferenceSystem::createFromUserInput( const QString &definitio
 
   if ( OSRSetFromUserInput( crs, definition.toLocal8Bit().constData() ) == OGRERR_NONE )
   {
-    if ( OSRExportToWkt( crs, &wkt ) == OGRERR_NONE )
-    {
-      userWkt = wkt;
-      CPLFree( wkt );
-    }
+    userWkt = QgsOgrUtils::OGRSpatialReferenceToWkt( crs );
     OSRDestroySpatialReference( crs );
   }
   //QgsDebugMsg( "definition: " + definition + " wkt = " + wkt );

src/core/qgsogrutils.cpp

@@ -26,6 +26,8 @@
 #include <cpl_error.h>
 #include <QJsonDocument>
 
+#include "ogr_srs_api.h"
+
 // Starting with GDAL 2.2, there are 2 concepts: unset fields and null fields
 // whereas previously there was only unset fields. For QGIS purposes, both
 // states (unset/null) are equivalent.
@@ -714,3 +716,31 @@ QStringList QgsOgrUtils::cStringListToQStringList( char **stringList )
   return strings;
 }
 
+QString QgsOgrUtils::OGRSpatialReferenceToWkt( OGRSpatialReferenceH srs )
+{
+  if ( !srs )
+    return QString();
+
+  char *pszWkt = nullptr;
+#if GDAL_VERSION_NUM >= GDAL_COMPUTE_VERSION(3,0,0)
+  const QByteArray multiLineOption = QStringLiteral( "MULTILINE=NO" ).toLocal8Bit();
+  const QByteArray formatOption = QStringLiteral( "FORMAT=WKT2" ).toLocal8Bit();
+  const char *const options[] = {multiLineOption.constData(), formatOption.constData(), nullptr};
+  OSRExportToWktEx( srs, &pszWkt, options );
+#else
+  OSRExportToWkt( srs, &pszWkt );
+#endif
+
+  const QString res( pszWkt );
+  CPLFree( pszWkt );
+  return res;
+}
+
+QgsCoordinateReferenceSystem QgsOgrUtils::OGRSpatialReferenceToCrs( OGRSpatialReferenceH srs )
+{
+  const QString wkt = OGRSpatialReferenceToWkt( srs );
+  if ( wkt.isEmpty() )
+    return QgsCoordinateReferenceSystem();
+
+  return QgsCoordinateReferenceSystem::fromWkt( wkt );
+}

src/core/qgsogrutils.h

@@ -268,6 +268,23 @@ class CORE_EXPORT QgsOgrUtils
      * \since QGIS 3.4.9
      */
     static QgsWkbTypes::Type ogrGeometryTypeToQgsWkbType( OGRwkbGeometryType ogrGeomType );
+
+    /**
+     * Returns a WKT string corresponding to the specified OGR \a srs object.
+     *
+     * The WKT string format will be selected using the most appropriate format (usually WKT2 if GDAL 3 is available).
+     *
+     * \since QGIS 3.10.1
+     */
+    static QString OGRSpatialReferenceToWkt( OGRSpatialReferenceH srs );
+
+    /**
+     * Returns a QgsCoordinateReferenceSystem corresponding to the specified OGR \a srs object, or an invalid
+     * QgsCoordinateReferenceSystem if \a srs could not be converted.
+     *
+     * \since QGIS 3.10.1
+     */
+    static QgsCoordinateReferenceSystem OGRSpatialReferenceToCrs( OGRSpatialReferenceH srs );
 };
 
 #endif // QGSOGRUTILS_H