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, 27 insertions, 0 deletions

diff --git a/test/unit/test_c_api.cpp b/test/unit/test_c_api.cpp
index 486ab0c7..12e98d7e 100644
--- a/test/unit/test_c_api.cpp
+++ b/test/unit/test_c_api.cpp
@@ -3220,4 +3220,31 @@ TEST_F(CApi, proj_get_crs_info_list_from_database) {
         proj_crs_info_list_destroy(list);
     }
 }
+
+// ---------------------------------------------------------------------------
+
+TEST_F(CApi, proj_normalize_for_visualization) {
+
+    {
+        auto P = proj_create(m_ctxt, "+proj=utm +zone=31 +ellps=WGS84");
+        ObjectKeeper keeper_P(P);
+        ASSERT_NE(P, nullptr);
+        auto Pnormalized = proj_normalize_for_visualization(m_ctxt, P);
+        ObjectKeeper keeper_Pnormalized(Pnormalized);
+        EXPECT_EQ(Pnormalized, nullptr);
+    }
+
+    auto P = proj_create_crs_to_crs(m_ctxt, "EPSG:4326", "EPSG:32631", nullptr);
+    ObjectKeeper keeper_P(P);
+    ASSERT_NE(P, nullptr);
+    auto Pnormalized = proj_normalize_for_visualization(m_ctxt, P);
+    ObjectKeeper keeper_Pnormalized(Pnormalized);
+    ASSERT_NE(Pnormalized, nullptr);
+    auto projstr = proj_as_proj_string(m_ctxt, Pnormalized, PJ_PROJ_5, nullptr);
+    ASSERT_NE(projstr, nullptr);
+    EXPECT_EQ(std::string(projstr),
+              "+proj=pipeline +step +proj=unitconvert +xy_in=deg +xy_out=rad "
+              "+step +proj=utm +zone=31 +ellps=WGS84");
+}
+
 } // namespace