JSONFG reader/writer: report/write measure unit and description

Author: rouault

apps/ogr2ogr_lib.cpp

@@ -4868,6 +4868,29 @@ SetupTargetLayer::Setup(OGRLayer *poSrcLayer, const char *pszNewLayerName,
             oCoordPrec.dfMResolution = psOptions->dfMRes;
         }
 
+        // For JSONFG
+        CSLConstList papszMeasures = poSrcLayer->GetMetadata("MEASURES");
+        if (papszMeasures && pszDestCreationOptions)
+        {
+            for (const char *pszItem : {"UNIT", "DESCRIPTION"})
+            {
+                const char *pszValue =
+                    CSLFetchNameValue(papszMeasures, pszItem);
+                if (pszValue)
+                {
+                    const std::string osOptionName =
+                        std::string("MEASURE_").append(pszItem);
+                    if (strstr(pszDestCreationOptions, osOptionName.c_str()) &&
+                        CSLFetchNameValue(m_papszLCO, osOptionName.c_str()) ==
+                            nullptr)
+                    {
+                        papszLCOTemp = CSLSetNameValue(
+                            papszLCOTemp, osOptionName.c_str(), pszValue);
+                    }
+                }
+            }
+        }
+
         auto poSrcDriver = m_poSrcDS->GetDriver();
 
         // Force FID column as 64 bit if the source feature has a 64 bit FID,

autotest/ogr/ogr_jsonfg.py

@@ -1627,3 +1627,60 @@ def test_jsonfg_write_circular_string_longer_than_11_points(tmp_vsimem):
             f.GetGeometryRef().ExportToIsoWkt()
             == "COMPOUNDCURVE (CIRCULARSTRING (0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 0,10 0),CIRCULARSTRING (10 0,11 0,12 0))"
         )
+
+
+@pytest.mark.parametrize("single_layer", ["YES", "NO"])
+def test_jsonfg_write_read_measure_unit_description(tmp_vsimem, single_layer):
+
+    out_filename = tmp_vsimem / "out.json"
+    with gdal.GetDriverByName("JSONFG").CreateVector(
+        out_filename, options=["SINGLE_LAYER=" + single_layer]
+    ) as ds:
+        srs = osr.SpatialReference(epsg=32631)
+        lyr = ds.CreateLayer(
+            "test",
+            srs=srs,
+            options=["MEASURE_UNIT=my_unit", "MEASURE_DESCRIPTION=my_description"],
+        )
+        f = ogr.Feature(lyr.GetLayerDefn())
+        g = ogr.CreateGeometryFromWkt("POINT M (1 2 3)")
+        f.SetGeometry(g)
+        lyr.CreateFeature(f)
+
+    with gdal.VSIFile(out_filename, "rb") as f:
+        j = json.loads(f.read())
+        if single_layer == "YES":
+            assert "measures" in j
+            assert j["measures"] == {
+                "enabled": True,
+                "unit": "my_unit",
+                "description": "my_description",
+            }
+        else:
+            assert "measures" in j["features"][0]
+            assert j["features"][0]["measures"] == {
+                "enabled": True,
+                "unit": "my_unit",
+                "description": "my_description",
+            }
+
+    with ogr.Open(out_filename) as ds:
+        lyr = ds.GetLayer(0)
+        assert lyr.GetMetadata_Dict("MEASURES") == {
+            "UNIT": "my_unit",
+            "DESCRIPTION": "my_description",
+        }
+        f = lyr.GetNextFeature()
+        assert f.GetGeometryRef().ExportToIsoWkt() == "POINT M (1 2 3)"
+
+    out2_filename = tmp_vsimem / "out2.json"
+    gdal.VectorTranslate(out2_filename, out_filename, format="JSONFG")
+
+    with ogr.Open(out2_filename) as ds:
+        lyr = ds.GetLayer(0)
+        assert lyr.GetMetadata_Dict("MEASURES") == {
+            "UNIT": "my_unit",
+            "DESCRIPTION": "my_description",
+        }
+        f = lyr.GetNextFeature()
+        assert f.GetGeometryRef().ExportToIsoWkt() == "POINT M (1 2 3)"

doc/source/drivers/vector/jsonfg.rst

@@ -108,6 +108,16 @@ Circular-arc geometry support
 Reading and writing of CircularString, CompoundCurve, CurvePolygon, MultiCurve
 and MultiSurface geometries is supported.
 
+Geometry measure support
+------------------------
+
+.. versionadded:: 3.12
+
+Geometry with measure values (M component) can be read and written. The unit
+and description of the measure, if included in the file, is reported in the
+``MEASURES`` layer metadata domain. On the writing side, the :lco:`MEASURE_UNIT`
+and :lco:`MEASURE_DESCRIPTION` layer creation option can be set.
+
 Configuration options
 ---------------------
 
@@ -210,6 +220,18 @@ The following layer creation options are supported:
 
       Auto-generate feature ids
 
+-  .. lco:: MEASURE_UNIT
+      :choices: <string>
+      :since: 3.12
+
+      Unit of measures (M) values
+
+-  .. lco:: MEASURE_DESCRIPTION
+      :choices: <string>
+      :since: 3.12
+
+      Description of measures (M) values
+
 VSI Virtual File System API support
 -----------------------------------
 

ogr/ogrsf_frmts/jsonfg/ogr_jsonfg.h

@@ -236,6 +236,9 @@ class OGRJSONFGWriteLayer final : public OGRLayer
     bool m_bPolyhedraWritten = false;
     bool m_bCurveWritten = false;
     bool m_bMeasureWritten = false;
+    bool bLayerLevelMeasuresWritten_ = false;
+    std::string osMeasureUnit_{};
+    std::string osMeasureDescription_{};
 
     OGRGeoJSONWriteOptions oWriteOptions_{};
     OGRGeoJSONWriteOptions oWriteOptionsPlace_{};
@@ -415,6 +418,8 @@ class OGRJSONFGReader
     char chNestedAttributeSeparator_ = 0;
     bool bArrayAsString_ = false;
     bool bDateAsString_ = false;
+    std::string osMeasureUnit_{};
+    std::string osMeasureDescription_{};
 
     /** Layer building context, specific to one layer. */
     struct LayerDefnBuildContext
@@ -515,6 +520,14 @@ class OGRJSONFGReader
          * AnalyzeWithStreamingParser() mode) */
         OGRJSONFGStreamedLayer *poStreamedLayer = nullptr;
 
+        bool bSameMeasureMetadata = true;
+
+        //! Measure unit
+        std::string osMeasureUnit{};
+
+        //! Measure description
+        std::string osMeasureDescription{};
+
         LayerDefnBuildContext() = default;
         LayerDefnBuildContext(LayerDefnBuildContext &&) = default;
         LayerDefnBuildContext &operator=(LayerDefnBuildContext &&) = default;

ogr/ogrsf_frmts/jsonfg/ogrjsonfgdriver.cpp

@@ -135,6 +135,10 @@ void RegisterOGRJSONFG()
         "  </Option>"
         "  <Option name='ID_GENERATE' type='boolean' "
         "description='Auto-generate feature ids' default='NO'/>"
+        "  <Option name='MEASURE_UNIT' type='string' "
+        "description='Unit of measures (M) values'/>"
+        "  <Option name='MEASURE_DESCRIPTION' type='string' "
+        "description='Description of measures (M) values'/>"
         "</LayerCreationOptionList>");
 
     poDriver->SetMetadataItem(

ogr/ogrsf_frmts/jsonfg/ogrjsonfgreader.cpp

@@ -446,6 +446,32 @@ bool OGRJSONFGReader::FinalizeGenerateLayerDefns(bool bStreamedLayer)
         }
     }
 
+    json_object *poMeasures = nullptr;
+    if (json_object_object_get_ex(poObject_, "measures", &poMeasures) &&
+        json_object_get_type(poMeasures) == json_type_object)
+    {
+        json_object *poEnabled = nullptr;
+        if (json_object_object_get_ex(poMeasures, "enabled", &poEnabled) &&
+            json_object_get_type(poEnabled) == json_type_boolean &&
+            json_object_get_boolean(poEnabled))
+        {
+            json_object *poUnit = nullptr;
+            if (json_object_object_get_ex(poMeasures, "unit", &poUnit) &&
+                json_object_get_type(poUnit) == json_type_string)
+            {
+                osMeasureUnit_ = json_object_get_string(poUnit);
+            }
+
+            json_object *poDescription = nullptr;
+            if (json_object_object_get_ex(poMeasures, "description",
+                                          &poDescription) &&
+                json_object_get_type(poDescription) == json_type_string)
+            {
+                osMeasureDescription_ = json_object_get_string(poDescription);
+            }
+        }
+    }
+
     // Finalize layer definition building and create OGRLayer objects
     for (auto &oBuildContextIter : oMapBuildContext_)
     {
@@ -673,6 +699,38 @@ void OGRJSONFGReader::FinalizeBuildContext(LayerDefnBuildContext &oBuildContext,
     if (oBuildContext.bNeedFID64)
         poLayer->SetMetadataItem(OLMD_FID64, "YES");
 
+    if (oBuildContext.bSameMeasureMetadata &&
+        (!oBuildContext.osMeasureUnit.empty() ||
+         !oBuildContext.osMeasureDescription.empty()))
+    {
+        if (!oBuildContext.osMeasureUnit.empty())
+        {
+            poLayer->SetMetadataItem(
+                "UNIT", oBuildContext.osMeasureUnit.c_str(), "MEASURES");
+        }
+
+        if (!oBuildContext.osMeasureDescription.empty())
+        {
+            poLayer->SetMetadataItem("DESCRIPTION",
+                                     oBuildContext.osMeasureDescription.c_str(),
+                                     "MEASURES");
+        }
+    }
+    else
+    {
+        if (!osMeasureUnit_.empty())
+        {
+            poLayer->SetMetadataItem("UNIT", osMeasureUnit_.c_str(),
+                                     "MEASURES");
+        }
+
+        if (!osMeasureDescription_.empty())
+        {
+            poLayer->SetMetadataItem("DESCRIPTION",
+                                     osMeasureDescription_.c_str(), "MEASURES");
+        }
+    }
+
     if (poStreamedLayer)
     {
         poStreamedLayer->SetFeatureCount(oBuildContext.nFeatureCount);
@@ -1058,6 +1116,45 @@ bool OGRJSONFGReader::GenerateLayerDefnFromFeature(json_object *poObj)
         }
     }
 
+    if (poContext->bSameMeasureMetadata)
+    {
+        json_object *poMeasures = nullptr;
+        if (json_object_object_get_ex(poObj, "measures", &poMeasures) &&
+            json_object_get_type(poMeasures) == json_type_object)
+        {
+            json_object *poEnabled = nullptr;
+            if (json_object_object_get_ex(poMeasures, "enabled", &poEnabled) &&
+                json_object_get_type(poEnabled) == json_type_boolean &&
+                json_object_get_boolean(poEnabled))
+            {
+                json_object *poUnit = nullptr;
+                if (json_object_object_get_ex(poMeasures, "unit", &poUnit) &&
+                    json_object_get_type(poUnit) == json_type_string)
+                {
+                    if (poContext->osMeasureUnit.empty())
+                        poContext->osMeasureUnit =
+                            json_object_get_string(poUnit);
+                    else if (poContext->osMeasureUnit !=
+                             json_object_get_string(poUnit))
+                        poContext->bSameMeasureMetadata = false;
+                }
+
+                json_object *poDescription = nullptr;
+                if (json_object_object_get_ex(poMeasures, "description",
+                                              &poDescription) &&
+                    json_object_get_type(poDescription) == json_type_string)
+                {
+                    if (poContext->osMeasureDescription.empty())
+                        poContext->osMeasureDescription =
+                            json_object_get_string(poDescription);
+                    else if (poContext->osMeasureDescription !=
+                             json_object_get_string(poDescription))
+                        poContext->bSameMeasureMetadata = false;
+                }
+            }
+        }
+    }
+
     /* -------------------------------------------------------------------- */
     /*      Deal with place / geometry                                      */
     /* -------------------------------------------------------------------- */

ogr/ogrsf_frmts/jsonfg/ogrjsonfgwritelayer.cpp

@@ -71,6 +71,10 @@ OGRJSONFGWriteLayer::OGRJSONFGWriteLayer(
     bWriteFallbackGeometry_ = CPLTestBool(
         CSLFetchNameValueDef(papszOptions, "WRITE_GEOMETRY", "TRUE"));
 
+    osMeasureUnit_ = CSLFetchNameValueDef(papszOptions, "MEASURE_UNIT", "");
+    osMeasureDescription_ =
+        CSLFetchNameValueDef(papszOptions, "MEASURE_DESCRIPTION", "");
+
     VSILFILE *fp = poDS_->GetOutputFile();
     if (poDS_->IsSingleOutputLayer())
     {
@@ -81,6 +85,32 @@ OGRJSONFGWriteLayer::OGRJSONFGWriteLayer(
         json_object_put(poFeatureType);
         if (!osCoordRefSys.empty())
             VSIFPrintfL(fp, "\"coordRefSys\" : %s,\n", osCoordRefSys.c_str());
+
+        if (!osMeasureUnit_.empty() || !osMeasureDescription_.empty())
+        {
+            m_bMeasureWritten = true;
+            bLayerLevelMeasuresWritten_ = true;
+            VSIFPrintfL(fp, "\"measures\": {\n");
+            VSIFPrintfL(fp, "  \"enabled\": true");
+            if (!osMeasureUnit_.empty())
+            {
+                auto poUnit = json_object_new_string(osMeasureUnit_.c_str());
+                VSIFPrintfL(fp, ",\n  \"unit\": %s",
+                            json_object_to_json_string_ext(
+                                poUnit, JSON_C_TO_STRING_SPACED));
+                json_object_put(poUnit);
+            }
+            if (!osMeasureDescription_.empty())
+            {
+                auto poDescription =
+                    json_object_new_string(osMeasureDescription_.c_str());
+                VSIFPrintfL(fp, ",\n  \"description\": %s",
+                            json_object_to_json_string_ext(
+                                poDescription, JSON_C_TO_STRING_SPACED));
+                json_object_put(poDescription);
+            }
+            VSIFPrintfL(fp, "\n},\n");
+        }
     }
 }
 
@@ -365,10 +395,36 @@ OGRErr OGRJSONFGWriteLayer::ICreateFeature(OGRFeature *poFeature)
         }
 
         if (poGeom->IsMeasured())
+        {
+            if (!bLayerLevelMeasuresWritten_)
+            {
+                json_object *poMeasures = json_object_new_object();
+                json_object_object_add(poMeasures, "enabled",
+                                       json_object_new_boolean(true));
+                if (!poDS_->IsSingleOutputLayer())
+                {
+                    if (!osMeasureUnit_.empty())
+                    {
+                        json_object_object_add(
+                            poMeasures, "unit",
+                            json_object_new_string(osMeasureUnit_.c_str()));
+                    }
+                    if (!osMeasureDescription_.empty())
+                    {
+                        json_object_object_add(
+                            poMeasures, "description",
+                            json_object_new_string(
+                                osMeasureDescription_.c_str()));
+                    }
+                }
+                json_object_object_add(poObj, "measures", poMeasures);
+            }
+        }
+        else if (bLayerLevelMeasuresWritten_)
         {
             json_object *poMeasures = json_object_new_object();
             json_object_object_add(poMeasures, "enabled",
-                                   json_object_new_boolean(true));
+                                   json_object_new_boolean(false));
             json_object_object_add(poObj, "measures", poMeasures);
         }
     }