[ogr] Read GPX elevation values as geometry Z values

(cherry-picked from 4080aad)

src/providers/ogr/qgsogrprovider.cpp

@@ -2841,6 +2841,7 @@ void QgsOgrProvider::open( OpenMode mode )
   QgsDebugMsg( "mLayerName: " + mLayerName );
   QgsDebugMsg( "mSubsetString: " + mSubsetString );
   CPLSetConfigOption( "OGR_ORGANIZE_POLYGONS", "ONLY_CCW" );  // "SKIP" returns MULTIPOLYGONs for multiringed POLYGONs
+  CPLSetConfigOption( "GPX_ELE_AS_25D", "YES" );  // use GPX elevation as z values
 
   if ( mFilePath.startsWith( "MySQL:" ) && !mLayerName.isEmpty() && !mFilePath.endsWith( ",tables=" + mLayerName ) )
   {

tests/src/python/test_provider_ogr.py

@@ -153,5 +153,23 @@ def testNoDanglingFileDescriptorAfterCloseVariant2(self):
         os.unlink(datasource)
         self.assertFalse(os.path.exists(datasource))
 
+    def testGpxElevation(self):
+        # GPX without elevation data
+        datasource = os.path.join(TEST_DATA_DIR, 'noelev.gpx')
+        vl = QgsVectorLayer(u'{}|layername=routes'.format(datasource), u'test', u'ogr')
+        self.assertTrue(vl.isValid())
+        f = next(vl.getFeatures())
+        self.assertEqual(f.constGeometry().geometry().wkbType(), QgsWKBTypes.LineString)
+
+        # GPX with elevation data
+        datasource = os.path.join(TEST_DATA_DIR, 'elev.gpx')
+        vl = QgsVectorLayer(u'{}|layername=routes'.format(datasource), u'test', u'ogr')
+        self.assertTrue(vl.isValid())
+        f = next(vl.getFeatures())
+        self.assertEqual(f.constGeometry().geometry().wkbType(), QgsWKBTypes.LineString25D)
+        self.assertEqual(f.constGeometry().geometry().pointN(0).z(), 1)
+        self.assertEqual(f.constGeometry().geometry().pointN(1).z(), 2)
+        self.assertEqual(f.constGeometry().geometry().pointN(2).z(), 3)
+
 if __name__ == '__main__':
     unittest.main()

tests/testdata/elev.gpx

@@ -0,0 +1,15 @@
+<?xml version="1.0"?>
+<gpx version="1.1" creator="GDAL 1.11.3" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.topografix.com/GPX/1/1" xsi:schemaLocation="http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd">
+<metadata><bounds minlat="56.134840267383296" minlon="-3.877982991747363" maxlat="56.135514185147493" maxlon="-3.852565020533009"/></metadata>                  
+<rte>
+  <rtept lat="56.134840267383296" lon="-3.877982991747363">
+    <ele>1</ele>
+  </rtept>
+  <rtept lat="56.134933668432737" lon="-3.865962243986197">
+    <ele>2</ele>
+  </rtept>
+  <rtept lat="56.135514185147493" lon="-3.852565020533009">
+    <ele>3</ele>
+  </rtept>
+</rte>
+</gpx>

tests/testdata/noelev.gpx

@@ -0,0 +1,12 @@
+<?xml version="1.0"?>
+<gpx version="1.1" creator="GDAL 1.11.3" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.topografix.com/GPX/1/1" xsi:schemaLocation="http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd">
+<metadata><bounds minlat="56.134840267383240" minlon="-3.877982991747359" maxlat="56.135514185147436" maxlon="-3.852565020533005"/></metadata>                  
+<rte>
+  <rtept lat="56.13484026738324" lon="-3.877982991747359">
+  </rtept>
+  <rtept lat="56.13493366843268" lon="-3.865962243986193">
+  </rtept>
+  <rtept lat="56.135514185147436" lon="-3.852565020533005">
+  </rtept>
+</rte>
+</gpx>