TopoJSON: read a top level 'crs' member (fixes OSGeo#12216)

Author: rouault

autotest/ogr/data/topojson/topojson_with_crs.topojson

@@ -0,0 +1,14 @@
+{
+"type":"Topology",
+"crs": { "type": "name", "properties": { "name": "urn:ogc:def:crs:OGC:1.3:CRS84" } },
+"arcs": [
+[[0.0, 0.0], [10, 0], [0, 10]],
+],
+"transform": {
+"scale": [1.0,10.0],"translate": [100.0,1000.0]
+},
+"objects": {
+"a_layer" : {"type": "GeometryCollection", "geometries" : [ {"type": "LineString", "arcs": [0], "properties": { "name": "line", "id": "foo"} } ] },
+"foo" : {"type": "LineString", "arcs": [0], "id" : "1" }
+}
+}

autotest/ogr/ogr_topojson.py

@@ -135,11 +135,13 @@ def test_ogr_topojson_no_transform():
     ds = ogr.Open("data/topojson/topojson3.topojson")
     lyr = ds.GetLayer(0)
     assert lyr.GetName() == "a_layer"
+    assert lyr.GetSpatialRef() is None
     feat = lyr.GetNextFeature()
     ogrtest.check_feature_geometry(feat, "LINESTRING (0 0,10 0,0 10,10 0,0 0)")
 
     lyr = ds.GetLayer(1)
     assert lyr.GetName() == "TopoJSON"
+    assert lyr.GetSpatialRef() is None
     feat = lyr.GetNextFeature()
     ogrtest.check_feature_geometry(feat, "LINESTRING (0 0,10 0,0 10,10 0,0 0)")
     ds = None
@@ -174,3 +176,17 @@ def test_ogr_topojson_force_opening_url():
 
     drv = gdal.IdentifyDriverEx("http://example.com", allowed_drivers=["TopoJSON"])
     assert drv.GetDescription() == "TopoJSON"
+
+
+###############################################################################
+# Test CRS support
+
+
+def test_ogr_topojson_crs():
+
+    ds = ogr.Open("data/topojson/topojson_with_crs.topojson")
+    lyr = ds.GetLayer(0)
+    assert lyr.GetSpatialRef().GetAuthorityCode(None) == "4326"
+
+    lyr = ds.GetLayer(1)
+    assert lyr.GetSpatialRef().GetAuthorityCode(None) == "4326"

ogr/ogrsf_frmts/geojson/ogrtopojsonreader.cpp

@@ -14,6 +14,7 @@
 #include "ogrgeojsonutils.h"
 #include "ogrlibjsonutils.h"
 #include "ogr_geojson.h"
+#include "ogrgeojsongeometry.h"
 #include <json.h>  // JSON-C
 #include "ogr_api.h"
 
@@ -456,9 +457,9 @@ EstablishLayerDefn(int nPrevFieldIdx, std::vector<int> &anCurFieldIndices,
 
 static bool
 ParseObjectMain(const char *pszId, json_object *poObj,
-                OGRGeoJSONDataSource *poDS, OGRGeoJSONLayer **ppoMainLayer,
-                json_object *poArcs, ScalingParams *psParams,
-                std::vector<int> &anCurFieldIndices,
+                const OGRSpatialReference *poSRS, OGRGeoJSONDataSource *poDS,
+                OGRGeoJSONLayer **ppoMainLayer, json_object *poArcs,
+                ScalingParams *psParams, std::vector<int> &anCurFieldIndices,
                 std::map<std::string, int> &oMapFieldNameToIdx,
                 std::vector<std::unique_ptr<OGRFieldDefn>> &apoFieldDefn,
                 gdal::DirectedAcyclicGraph<int, std::string> &dag,
@@ -498,6 +499,9 @@ ParseObjectMain(const char *pszId, json_object *poObj,
                     poLayer->SetSupportsZGeometries(false);
                     OGRFeatureDefn *poDefn = poLayer->GetLayerDefn();
 
+                    whileUnsealing(poDefn)->GetGeomFieldDefn(0)->SetSpatialRef(
+                        poSRS);
+
                     const auto nGeometries =
                         json_object_array_length(poGeometries);
                     // First pass to establish schema.
@@ -573,6 +577,10 @@ ParseObjectMain(const char *pszId, json_object *poObj,
 
                     (*ppoMainLayer)->SetSupportsZGeometries(false);
 
+                    whileUnsealing((*ppoMainLayer)->GetLayerDefn())
+                        ->GetGeomFieldDefn(0)
+                        ->SetSpatialRef(poSRS);
+
                     apoFieldDefn.emplace_back(
                         std::make_unique<OGRFieldDefn>("id", OFTString));
                     oMapFieldNameToIdx["id"] = 0;
@@ -701,6 +709,8 @@ void OGRTopoJSONReader::ReadLayers(OGRGeoJSONDataSource *poDS)
     if (poObjects == nullptr)
         return;
 
+    OGRSpatialReference *poSRS = OGRGeoJSONReadSpatialReference(poGJObject_);
+
     std::vector<int> anCurFieldIndices;
     std::map<std::string, int> oMapFieldNameToIdx;
     std::vector<std::unique_ptr<OGRFieldDefn>> apoFieldDefn;
@@ -717,10 +727,10 @@ void OGRTopoJSONReader::ReadLayers(OGRGeoJSONDataSource *poDS)
         json_object_object_foreachC(poObjects, it)
         {
             json_object *poObj = it.val;
-            bNeedSecondPass |=
-                ParseObjectMain(it.key, poObj, poDS, &poMainLayer, poArcs,
-                                &sParams, anCurFieldIndices, oMapFieldNameToIdx,
-                                apoFieldDefn, dag, aoSetUndeterminedTypeFields);
+            bNeedSecondPass |= ParseObjectMain(
+                it.key, poObj, poSRS, poDS, &poMainLayer, poArcs, &sParams,
+                anCurFieldIndices, oMapFieldNameToIdx, apoFieldDefn, dag,
+                aoSetUndeterminedTypeFields);
         }
         if (bNeedSecondPass)
         {
@@ -751,10 +761,10 @@ void OGRTopoJSONReader::ReadLayers(OGRGeoJSONDataSource *poDS)
         for (auto i = decltype(nObjects){0}; i < nObjects; i++)
         {
             json_object *poObj = json_object_array_get_idx(poObjects, i);
-            bNeedSecondPass |=
-                ParseObjectMain(nullptr, poObj, poDS, &poMainLayer, poArcs,
-                                &sParams, anCurFieldIndices, oMapFieldNameToIdx,
-                                apoFieldDefn, dag, aoSetUndeterminedTypeFields);
+            bNeedSecondPass |= ParseObjectMain(
+                nullptr, poObj, poSRS, poDS, &poMainLayer, poArcs, &sParams,
+                anCurFieldIndices, oMapFieldNameToIdx, apoFieldDefn, dag,
+                aoSetUndeterminedTypeFields);
         }
         if (bNeedSecondPass)
         {
@@ -781,4 +791,7 @@ void OGRTopoJSONReader::ReadLayers(OGRGeoJSONDataSource *poDS)
         poMainLayer->DetectGeometryType();
         poDS->AddLayer(poMainLayer);
     }
+
+    if (poSRS)
+        poSRS->Release();
 }