Partial revert BoundCRS identification change

Sync behavior with the new GDAL behavior, where a CRS defined using a proj string alone will be considered equivalent to the underlying source crs. (cherry picked from commit 2e37301)
qgis · Dec 20, 2019 · 7ddd181 · 7ddd181
1 parent 3d82440
commit 7ddd181
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Showing 4 changed files with 23 additions and 13 deletions.
diff --git a/src/core/qgscoordinatereferencesystem.cpp b/src/core/qgscoordinatereferencesystem.cpp
@@ -838,7 +838,7 @@ bool QgsCoordinateReferenceSystem::createFromProj( const QString &projString )
   {
     QString authName;
     QString authCode;
-    if ( QgsProjUtils::identifyCrs( crs.get(), authName, authCode ) )
+    if ( QgsProjUtils::identifyCrs( crs.get(), authName, authCode, QgsProjUtils::FlagMatchBoundCrsToUnderlyingSourceCrs ) )
     {
       const QString authid = QStringLiteral( "%1:%2" ).arg( authName, authCode );
       if ( createFromOgcWmsCrs( authid ) )

diff --git a/src/core/qgsprojutils.cpp b/src/core/qgsprojutils.cpp
@@ -184,7 +184,7 @@ QgsProjUtils::proj_pj_unique_ptr QgsProjUtils::crsToSingleCrs( const PJ *crs )
   return nullptr;
 }
 
-bool QgsProjUtils::identifyCrs( const PJ *crs, QString &authName, QString &authCode )
+bool QgsProjUtils::identifyCrs( const PJ *crs, QString &authName, QString &authCode, IdentifyFlags flags )
 {
   authName.clear();
   authCode.clear();
@@ -207,8 +207,11 @@ bool QgsProjUtils::identifyCrs( const PJ *crs, QString &authName, QString &authC
         {
           case PJ_TYPE_BOUND_CRS:
             // proj_identify also matches bound CRSes to the source CRS. But they are not the same as the source CRS, so we don't
-            // consider them a candidate for a match here
-            continue;
+            // consider them a candidate for a match here (depending on the identify flags, that is!)
+            if ( flags & FlagMatchBoundCrsToUnderlyingSourceCrs )
+              break;
+            else
+              continue;
 
           default:
             break;

diff --git a/src/core/qgsprojutils.h b/src/core/qgsprojutils.h
@@ -103,13 +103,20 @@ class CORE_EXPORT QgsProjUtils
      */
     static proj_pj_unique_ptr crsToSingleCrs( const PJ *crs );
 
+    //! Flags controlling CRS identification behavior
+    enum IdentifyFlag
+    {
+      FlagMatchBoundCrsToUnderlyingSourceCrs = 1 << 0, //!< Allow matching a BoundCRS object to its underlying SourceCRS
+    };
+    Q_DECLARE_FLAGS( IdentifyFlags, IdentifyFlag )
+
     /**
      * Attempts to identify a \a crs, matching it to a known authority and code within
      * an acceptable level of tolerance.
      *
      * Returns TRUE if a matching authority and code was found.
      */
-    static bool identifyCrs( const PJ *crs, QString &authName, QString &authCode );
+    static bool identifyCrs( const PJ *crs, QString &authName, QString &authCode, IdentifyFlags flags = nullptr );
 
     /**
      * Returns TRUE if a coordinate operation (specified via proj string) is available.
@@ -176,5 +183,6 @@ class CORE_EXPORT QgsProjContext
 #endif
 };
 
+Q_DECLARE_OPERATORS_FOR_FLAGS( QgsProjUtils::IdentifyFlags )
 #endif
 #endif // QGSPROJUTILS_H
diff --git a/tests/src/core/testqgscoordinatereferencesystem.cpp b/tests/src/core/testqgscoordinatereferencesystem.cpp
@@ -429,17 +429,16 @@ void TestQgsCoordinateReferenceSystem::fromProj4EPSG20936()
 {
 #if PROJ_VERSION_MAJOR>=6
   QgsCoordinateReferenceSystem crs = QgsCoordinateReferenceSystem::fromProj( QStringLiteral( "+proj=utm +zone=36 +south +a=6378249.145 +b=6356514.966398753 +towgs84=-143,-90,-294,0,0,0,0 +units=m +no_defs" ) );
-  QVERIFY( crs.isValid() );
-  QCOMPARE( crs.toWkt(), QStringLiteral( R"""(PROJCS["unknown",GEOGCS["unknown",DATUM["unknown",SPHEROID["unknown",6378249.145,293.466307699995],TOWGS84[-143,-90,-294,0,0,0,0]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",33],PARAMETER["scale_factor",0.9996],PARAMETER["false_easting",500000],PARAMETER["false_northing",10000000],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH]])""" ) );
-  QCOMPARE( crs.toProj(), QStringLiteral( "+proj=utm +zone=36 +south +a=6378249.145 +b=6356514.966398753 +towgs84=-143,-90,-294,0,0,0,0 +units=m +no_defs" ) );
 
-  // should ideally be EPSG:20936, but see https://github.com/OSGeo/PROJ/issues/1805
-  // so instead we get a BoundCRS of EPSG:20936 created from the proj string, which must be a user CRS (not EPSG:20936 itself!)
-#if 0
+  // For consistency with GDAL, we treat BoundCRS defined from a proj string as equivalent to their underlying CRS (ie. in this case EPSG:20936)
+
+  QVERIFY( crs.isValid() );
   QCOMPARE( crs.authid(), QStringLiteral( "EPSG:20936" ) );
-#endif
+  // must NOT be a BoundCRS!
+  QCOMPARE( crs.toWkt(), QStringLiteral( R"""(PROJCS["Arc 1950 / UTM zone 36S",GEOGCS["Arc 1950",DATUM["Arc_1950",SPHEROID["Clarke 1880 (Arc)",6378249.145,293.4663077,AUTHORITY["EPSG","7013"]],AUTHORITY["EPSG","6209"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4209"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",33],PARAMETER["scale_factor",0.9996],PARAMETER["false_easting",500000],PARAMETER["false_northing",10000000],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["EPSG","20936"]])""" ) );
+  QCOMPARE( crs.toProj(), QStringLiteral( "+proj=utm +zone=36 +south +a=6378249.145 +rf=293.4663077 +towgs84=-143,-90,-294,0,0,0,0 +units=m +no_defs" ) );
 
-  QCOMPARE( crs.ellipsoidAcronym(), QStringLiteral( "PARAMETER:6378249.14499999955296516:6356514.96639875322580338" ) );
+  QCOMPARE( crs.ellipsoidAcronym(), QStringLiteral( "EPSG:7013" ) );
 #endif
 }