Don't try to normalize proj coordinate operations constructed directly

from the proj string via the transform context This isn't possible -- only proj coordinate operations constructed from a src/dest CRS pair can be normalized, not those constructed from a proj string. It was redundant in any case, since we always normalize the available operations before giving users a choice of them. So just add some big bold warnings to the dox in case anyone is manually manipulating and adding custom operations, that these also MUST be pre-normalized Refs #33121, conversation in OSGeo/PROJ#1794
qgis · Dec 13, 2019 · 82a84ff · 82a84ff
1 parent 8994a4b
commit 82a84ff
Show file tree

Hide file tree

Showing 3 changed files with 13 additions and 11 deletions.
diff --git a/python/core/auto_generated/qgscoordinatetransformcontext.sip.in b/python/core/auto_generated/qgscoordinatetransformcontext.sip.in
@@ -134,12 +134,20 @@ from the specified ``sourceCrs`` to the specified ``destinationCrs``.
 string. If ``coordinateOperationProjString`` is empty, then the default Proj operation
 will be used when transforming between the coordinate reference systems.
 
+.. warning::
+
+   coordinateOperationProjString MUST be a proj string which has been normalized for
+   visualization, and must be constructed so that coordinates are always input and output
+   with x/y coordinate ordering. (Proj strings output by utilities such as projinfo will NOT
+   automatically normalize the axis order!).
+
 Returns ``True`` if the new coordinate operation was added successfully.
 
 .. seealso:: :py:func:`coordinateOperations`
 
 .. seealso:: :py:func:`removeCoordinateOperation`
 
+
 .. note::
 
    Requires Proj 6.0 or later. Builds based on earlier Proj versions will ignore this setting,

diff --git a/src/core/qgscoordinatetransform_p.cpp b/src/core/qgscoordinatetransform_p.cpp
@@ -355,17 +355,6 @@ ProjData QgsCoordinateTransformPrivate::threadLocalProjData()
 
       transform.reset();
     }
-    else
-    {
-      // transform may have either the source or destination CRS using swapped axis order. For QGIS, we ALWAYS need regular x/y axis order
-      transform.reset( proj_normalize_for_visualization( context, transform.get() ) );
-      if ( !transform )
-      {
-        const QString err = QObject::tr( "Cannot normalize transform between %1 and %2" ).arg( mSourceCRS.authid(),
-                            mDestCRS.authid() );
-        QgsMessageLog::logMessage( err, QString(), Qgis::Critical );
-      }
-    }
   }
 
   QString nonAvailableError;

diff --git a/src/core/qgscoordinatetransformcontext.h b/src/core/qgscoordinatetransformcontext.h
@@ -140,6 +140,11 @@ class CORE_EXPORT QgsCoordinateTransformContext
      * string. If \a coordinateOperationProjString is empty, then the default Proj operation
      * will be used when transforming between the coordinate reference systems.
      *
+     * \warning coordinateOperationProjString MUST be a proj string which has been normalized for
+     * visualization, and must be constructed so that coordinates are always input and output
+     * with x/y coordinate ordering. (Proj strings output by utilities such as projinfo will NOT
+     * automatically normalize the axis order!).
+     *
      * Returns TRUE if the new coordinate operation was added successfully.
      *
      * \see coordinateOperations()