src/geom/util/GeometryCombiner.cpp

   1 /**********************************************************************
   2  *
   3  * GEOS - Geometry Engine Open Source
   4  * http://geos.osgeo.org
   5  *
   6  * Copyright (C) 2006-2011 Refractions Research Inc.
   7  *
   8  * This is free software; you can redistribute and/or modify it under
   9  * the terms of the GNU Lesser General Public Licence as published
  10  * by the Free Software Foundation.
  11  * See the COPYING file for more information.
  12  *
  13  **********************************************************************
  14  *
  15  * Last port: geom/util/GeometryCombiner.java r320 (JTS-1.12)
  16  *
  17  **********************************************************************/
  18
  19 #include <geos/geom/util/GeometryCombiner.h>
  20 #include <geos/geom/Geometry.h>
  21 #include <geos/geom/GeometryFactory.h>
  22 #include <geos/geom/GeometryCollection.h>
  23
  24 namespace geos {
  25 namespace geom { // geos.geom
  26 namespace util { // geos.geom.util
  27
  28 Geometry* GeometryCombiner::combine(std::vector<Geometry*> const& geoms)
  29 {
  30     GeometryCombiner combiner(geoms);
  31     return combiner.combine();
  32 }
  33
  34 Geometry* GeometryCombiner::combine(const Geometry* g0, const Geometry* g1)
  35 {
  36     std::vector<Geometry*> geoms;
  37     geoms.push_back(const_cast<Geometry*>(g0));
  38     geoms.push_back(const_cast<Geometry*>(g1));
  39
  40     GeometryCombiner combiner(geoms);
  41     return combiner.combine();
  42 }
  43
  44 Geometry* GeometryCombiner::combine(const Geometry* g0, const Geometry* g1,
  45                                     const Geometry* g2)
  46 {
  47     std::vector<Geometry*> geoms;
  48     geoms.push_back(const_cast<Geometry*>(g0));
  49     geoms.push_back(const_cast<Geometry*>(g1));
  50     geoms.push_back(const_cast<Geometry*>(g2));
  51
  52     GeometryCombiner combiner(geoms);
  53     return combiner.combine();
  54 }
  55
  56 GeometryCombiner::GeometryCombiner(std::vector<Geometry*> const& geoms)
  57   : geomFactory(extractFactory(geoms)), skipEmpty(false), inputGeoms(geoms)
  58 {
  59 }
  60
  61 GeometryFactory const*
  62 GeometryCombiner::extractFactory(std::vector<Geometry*> const& geoms)
  63 {
  64     return geoms.empty() ? NULL : geoms.front()->getFactory();
  65 }
  66
  67 Geometry* GeometryCombiner::combine()
  68 {
  69     std::vector<Geometry*> elems;
  70
  71     std::vector<Geometry*>::const_iterator end = inputGeoms.end();
  72     for (std::vector<Geometry*>::const_iterator i = inputGeoms.begin();
  73          i != end; ++i)
  74     {
  75         extractElements(*i, elems);
  76     }
  77
  78     if (elems.empty()) {
  79         if (geomFactory != NULL) {
  80             return geomFactory->createGeometryCollection(NULL);
  81         }
  82         return NULL;
  83     }
  84
  85     // return the "simplest possible" geometry
  86     return geomFactory->buildGeometry(elems);
  87 }
  88
  89 void
  90 GeometryCombiner::extractElements(Geometry* geom, std::vector<Geometry*>& elems)
  91 {
  92     if (geom == NULL)
  93         return;
  94
  95     for (std::size_t i = 0; i < geom->getNumGeometries(); ++i) {
  96         Geometry* elemGeom = const_cast<Geometry*>(geom->getGeometryN(i));
  97         if (skipEmpty && elemGeom->isEmpty())
  98             continue;
  99         elems.push_back(elemGeom);
 100     }
 101 }
 102
 103 } // namespace geos.geom.util
 104 } // namespace geos.geom
 105 } // namespace geos
 106