restore behavior of QgsGeometry::combine on line strings (fixes #13274)

qgis · Oct 5, 2015 · ac3f390 · ac3f390
1 parent 52e7628
commit ac3f390
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Showing 3 changed files with 28 additions and 5 deletions.
diff --git a/src/core/geometry/qgsgeometry.cpp b/src/core/geometry/qgsgeometry.cpp
@@ -2297,6 +2297,3 @@ QDataStream& operator>>( QDataStream& in, QgsGeometry& geometry )
   geometry.fromWkb(( unsigned char* )data, byteArray.size() );
   return in;
 }
-
-
-
diff --git a/src/core/geometry/qgsgeos.cpp b/src/core/geometry/qgsgeos.cpp
@@ -1083,8 +1083,22 @@ QgsAbstractGeometryV2* QgsGeos::overlay( const QgsAbstractGeometryV2& geom, Over
         opGeom.reset( GEOSDifference_r( geosinit.ctxt, mGeos, geosGeom.get() ) );
         break;
       case UNION:
-        opGeom.reset( GEOSUnion_r( geosinit.ctxt, mGeos, geosGeom.get() ) );
-        break;
+      {
+        GEOSGeometry *unionGeometry = GEOSUnion_r( geosinit.ctxt, mGeos, geosGeom.get() );
+
+        if ( unionGeometry && GEOSGeomTypeId_r( geosinit.ctxt, unionGeometry ) == GEOS_MULTILINESTRING )
+        {
+          GEOSGeometry *mergedLines = GEOSLineMerge_r( geosinit.ctxt, unionGeometry );
+          if ( mergedLines )
+          {
+            GEOSGeom_destroy_r( geosinit.ctxt, unionGeometry );
+            unionGeometry = mergedLines;
+          }
+        }
+
+        opGeom.reset( unionGeometry );
+      }
+      break;
       case SYMDIFFERENCE:
         opGeom.reset( GEOSSymDifference_r( geosinit.ctxt, mGeos, geosGeom.get() ) );
         break;

diff --git a/tests/src/python/test_qgsgeometry.py b/tests/src/python/test_qgsgeometry.py
@@ -1377,5 +1377,17 @@ def testRegression13055(self):
         wkt = p.exportToWkt()
         assert compareWkt(expWkt, wkt), "testRegression13055 failed: mismatch Expected:\n%s\nGot:\n%s\n" % (expWkt, wkt)
 
+    def testRegression13274(self):
+        """ See http://hub.qgis.org/issues/13274
+            Testing that two combined linestrings produce another line string if possible
+        """
+        a = QgsGeometry.fromWkt('LineString (0 0, 1 0)')
+        b = QgsGeometry.fromWkt('LineString (1 0, 2 0)')
+        c = a.combine(b)
+
+        expWkt = 'LineString (0 0, 1 0, 2 0)'
+        wkt = c.exportToWkt()
+        assert compareWkt(expWkt, wkt), "testRegression13274 failed: mismatch Expected:\n%s\nGot:\n%s\n" % (expWkt, wkt)
+
 if __name__ == '__main__':
     unittest.main()