src/algorithm/CentroidLine.cpp

   1 /**********************************************************************
   2  *
   3  * GEOS - Geometry Engine Open Source
   4  * http://geos.osgeo.org
   5  *
   6  * Copyright (C) 2001-2002 Vivid Solutions Inc.
   7  * Copyright (C) 2005 Refractions Research Inc.
   8  *
   9  * This is free software; you can redistribute and/or modify it under
  10  * the terms of the GNU Lesser General Public Licence as published
  11  * by the Free Software Foundation.
  12  * See the COPYING file for more information.
  13  *
  14  **********************************************************************
  15  *
  16  **********************************************************************/
  17
  18 #include <geos/algorithm/CentroidLine.h>
  19 #include <geos/geom/Coordinate.h>
  20 #include <geos/geom/CoordinateSequence.h>
  21 #include <geos/geom/Geometry.h>
  22 #include <geos/geom/GeometryCollection.h>
  23 #include <geos/geom/LineString.h>
  24
  25 #include <typeinfo>
  26
  27 using namespace geos::geom;
  28
  29 namespace geos {
  30 namespace algorithm { // geos.algorithm
  31
  32 /*public*/
  33 void
  34 CentroidLine::add(const Geometry *geom)
  35 {
  36         const LineString* ls = dynamic_cast<const LineString*>(geom);
  37         if ( ls )
  38         {
  39                 add(ls->getCoordinatesRO());
  40                 return;
  41         }
  42
  43         const GeometryCollection* gc = dynamic_cast<const GeometryCollection*>(geom);
  44         if (gc)
  45         {
  46         for(std::size_t i=0, n=gc->getNumGeometries(); i<n; i++) {
  47                         add(gc->getGeometryN(i));
  48                 }
  49         }
  50 }
  51
  52 /*public*/
  53 void
  54 CentroidLine::add(const CoordinateSequence *pts)
  55 {
  56         std::size_t const npts=pts->getSize();
  57
  58         for(std::size_t i=1; i<npts; ++i)
  59         {
  60                 const Coordinate &p1=pts->getAt(i-1);
  61                 const Coordinate &p2=pts->getAt(i);
  62
  63                 double segmentLen=p1.distance(p2);
  64                 totalLength+=segmentLen;
  65                 double midx=(p1.x+p2.x)/2;
  66                 centSum.x+=segmentLen*midx;
  67                 double midy=(p1.y+p2.y)/2;
  68                 centSum.y+=segmentLen*midy;
  69         }
  70 }
  71
  72 Coordinate *
  73 CentroidLine::getCentroid() const
  74 {
  75         return new Coordinate(centSum.x/totalLength, centSum.y/totalLength);
  76 }
  77
  78 bool
  79 CentroidLine::getCentroid(Coordinate& c) const
  80 {
  81         if ( totalLength == 0.0 ) return false;
  82         c=Coordinate(centSum.x/totalLength, centSum.y/totalLength);
  83         return true;
  84 }
  85
  86 } // namespace geos.algorithm
  87 } // namespace geos