Add proj_normalize_for_visualization()

Fixes #1301

This function takes the output PJ from proj_create_crs_to_crs(),
and add (or undo) the needed axis swap operations so that the
object returned by proj_normalize_for_visualization() has the usual
GIS axis order.
In this implementation, this does something only if the coordinate
system of the source or target CRS, geographic or projected, has
NORTH, EAST ordering.
CompoundCRS wrapping those objects are also handled.

1 files changed, 32 insertions, 0 deletions

diff --git a/src/iso19111/c_api.cpp b/src/iso19111/c_api.cpp
index e62d3f56..1f4cecde 100644
--- a/src/iso19111/c_api.cpp
+++ b/src/iso19111/c_api.cpp
@@ -6767,3 +6767,35 @@ int proj_cs_get_axis_info(PJ_CONTEXT *ctx, const PJ *cs, int index,
     }
     return true;
 }
+
+// ---------------------------------------------------------------------------
+
+/** \brief Returns a PJ* object whose axis order is the one expected for
+ * visualization purposes.
+ *
+ * The input object must be a coordinate operation, that has been created with
+ * proj_create_crs_to_crs().
+ * If the axis order of its source or target CRS is northing,easting, then an
+ * axis swap operation will be inserted.
+ *
+ * @param ctx PROJ context, or NULL for default context
+ * @param obj Object of type CoordinateOperation,
+ * created with proj_create_crs_to_crs() (must not be NULL)
+ * @return a new PJ* object to free with proj_destroy() in case of success, or
+ * nullptr in case of error
+ */
+PJ *proj_normalize_for_visualization(PJ_CONTEXT *ctx, const PJ *obj) {
+    auto co = dynamic_cast<const CoordinateOperation *>(obj->iso_obj.get());
+    if (!co) {
+        proj_log_error(ctx, __FUNCTION__, "Object is not a CoordinateOperation "
+                                          "created with "
+                                          "proj_create_crs_to_crs");
+        return nullptr;
+    }
+    try {
+        return pj_obj_create(ctx, co->normalizeForVisualization());
+    } catch (const std::exception &e) {
+        proj_log_debug(ctx, __FUNCTION__, e.what());
+        return nullptr;
+    }
+}