OGR VRT: fix SrcRegion.clip at OGRVRTLayer level

Fixes OSGeo#11519

Author: rouault

autotest/ogr/ogr_vrt.py

@@ -624,6 +624,35 @@ def test_ogr_vrt_16(tmp_path):
     vrt_ds = None
 
 
+###############################################################################
+# Test SrcRegion.clip
+
+
+@pytest.mark.require_driver("CSV")
+@pytest.mark.require_geos
+def test_ogr_vrt_SrcRegion_clip(tmp_path):
+
+    f = open(tmp_path / "test.csv", "wb")
+    f.write("wkt_geom,val1,val2\n".encode("ascii"))
+    f.write('"LINESTRING (-1 0.5,1.5 0.5)",,\n'.encode("ascii"))
+    f.close()
+
+    vrt_xml = f"""
+<OGRVRTDataSource>
+    <OGRVRTLayer name="test">
+        <SrcDataSource relativeToVRT="0">{tmp_path}/test.csv</SrcDataSource>
+        <SrcLayer>test</SrcLayer>
+        <GeometryField encoding="WKT" field="wkt_geom"/>
+        <SrcRegion clip="true">POLYGON((0 0,0 1,1 1,1 0,0 0))</SrcRegion>
+    </OGRVRTLayer>
+</OGRVRTDataSource>"""
+    vrt_ds = ogr.Open(vrt_xml)
+    vrt_lyr = vrt_ds.GetLayerByName("test")
+    feat = vrt_lyr.GetNextFeature()
+    geom = feat.GetGeometryRef()
+    assert geom.ExportToWkt() == "LINESTRING (0.0 0.5,1.0 0.5)"
+
+
 ###############################################################################
 # Test explicit field definitions.
 

ogr/ogrsf_frmts/vrt/ogrvrtlayer.cpp

@@ -461,9 +461,10 @@ bool OGRVRTLayer::ParseGeometryField(CPLXMLNode *psNode,
     }
 
     // Do we have a SrcRegion?
-    const char *pszSrcRegion = CPLGetXMLValue(psNode, "SrcRegion", nullptr);
-    if (pszSrcRegion == nullptr && poProps == apoGeomFieldProps[0])
-        pszSrcRegion = CPLGetXMLValue(psNodeParent, "SrcRegion", nullptr);
+    const CPLXMLNode *psSrcRegionNode = CPLGetXMLNode(psNode, "SrcRegion");
+    if (psSrcRegionNode == nullptr && poProps == apoGeomFieldProps[0])
+        psSrcRegionNode = CPLGetXMLNode(psNodeParent, "SrcRegion");
+    const char *pszSrcRegion = CPLGetXMLValue(psSrcRegionNode, "", nullptr);
     if (pszSrcRegion != nullptr)
     {
         OGRGeometryFactory::createFromWkt(pszSrcRegion, nullptr,
@@ -475,7 +476,7 @@ bool OGRVRTLayer::ParseGeometryField(CPLXMLNode *psNode,
         }
 
         poProps->bSrcClip =
-            CPLTestBool(CPLGetXMLValue(psNode, "SrcRegion.clip", "FALSE"));
+            CPLTestBool(CPLGetXMLValue(psSrcRegionNode, "clip", "FALSE"));
     }
 
     // Set Extent if provided.