[OGR provider] Make extent() return a isNull() rectangle on empty layer (fixes #16721)

rouault · rouault · commit 3ff0f6979407 · 2017-11-12T14:56:05.000+01:00
diff --git a/src/providers/ogr/qgsogrprovider.cpp b/src/providers/ogr/qgsogrprovider.cpp
@@ -1097,25 +1097,25 @@ QgsRectangle QgsOgrProvider::extent() const
     }
 #endif
 
+    mExtent->MinX = std::numeric_limits<double>::max();
+    mExtent->MinY = std::numeric_limits<double>::max();
+    mExtent->MaxX = -std::numeric_limits<double>::max();
+    mExtent->MaxY = -std::numeric_limits<double>::max();
+
     // TODO: This can be expensive, do we really need it!
     if ( mOgrLayer == mOgrOrigLayer )
     {
       mOgrLayer->GetExtent( mExtent, true );
     }
     else
     {
-      mExtent->MinX = std::numeric_limits<double>::max();
-      mExtent->MinY = std::numeric_limits<double>::max();
-      mExtent->MaxX = -std::numeric_limits<double>::max();
-      mExtent->MaxY = -std::numeric_limits<double>::max();
-
       gdal::ogr_feature_unique_ptr f;
 
       mOgrLayer->ResetReading();
       while ( f.reset( mOgrLayer->GetNextFeature() ), f )
       {
         OGRGeometryH g = OGR_F_GetGeometryRef( f.get() );
-        if ( g )
+        if ( g && !OGR_G_IsEmpty( g ) )
         {
           OGREnvelope env;
           OGR_G_GetEnvelope( g, &env );
diff --git a/tests/src/python/test_provider_ogr_gpkg.py b/tests/src/python/test_provider_ogr_gpkg.py
@@ -589,6 +589,8 @@ def testGeopackageRefreshIfTableListUpdated(self):
 
         vl = QgsVectorLayer(u'{}'.format(tmpfile) + "|layername=" + "test", 'test', u'ogr')
 
+        self.assertTrue(vl.extent().isNull())
+
         time.sleep(1) # so timestamp gets updated
         ds = ogr.Open(tmpfile, update=1)
         ds.CreateLayer('test2', geom_type=ogr.wkbPoint)

Original file line number	Diff line number	Diff line change
`@@ -1097,25 +1097,25 @@ QgsRectangle QgsOgrProvider::extent() const`
`1097`	`1097`	`}`
`1098`	`1098`	`#endif`
`1099`	`1099`
	`1100`	`+ mExtent->MinX = std::numeric_limits<double>::max();`
	`1101`	`+ mExtent->MinY = std::numeric_limits<double>::max();`
	`1102`	`+ mExtent->MaxX = -std::numeric_limits<double>::max();`
	`1103`	`+ mExtent->MaxY = -std::numeric_limits<double>::max();`
	`1104`	`+`
`1100`	`1105`	`// TODO: This can be expensive, do we really need it!`
`1101`	`1106`	`if ( mOgrLayer == mOgrOrigLayer )`
`1102`	`1107`	`{`
`1103`	`1108`	`mOgrLayer->GetExtent( mExtent, true );`
`1104`	`1109`	`}`
`1105`	`1110`	`else`
`1106`	`1111`	`{`
`1107`		`- mExtent->MinX = std::numeric_limits<double>::max();`
`1108`		`- mExtent->MinY = std::numeric_limits<double>::max();`
`1109`		`- mExtent->MaxX = -std::numeric_limits<double>::max();`
`1110`		`- mExtent->MaxY = -std::numeric_limits<double>::max();`
`1111`		`-`
`1112`	`1112`	`gdal::ogr_feature_unique_ptr f;`
`1113`	`1113`
`1114`	`1114`	`mOgrLayer->ResetReading();`
`1115`	`1115`	`while ( f.reset( mOgrLayer->GetNextFeature() ), f )`
`1116`	`1116`	`{`
`1117`	`1117`	`OGRGeometryH g = OGR_F_GetGeometryRef( f.get() );`
`1118`		`- if ( g )`
	`1118`	`+ if ( g && !OGR_G_IsEmpty( g ) )`
`1119`	`1119`	`{`
`1120`	`1120`	`OGREnvelope env;`
`1121`	`1121`	`OGR_G_GetEnvelope( g, &env );`