include/geos/simplify/TopologyPreservingSimplifier.h

   1 /**********************************************************************
   2  * $Id$
   3  *
   4  * GEOS - Geometry Engine Open Source
   5  * http://geos.refractions.net
   6  *
   7  * Copyright (C) 2006 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 Licence as published
  11  * by the Free Software Foundation.
  12  * See the COPYING file for more information.
  13  *
  14  **********************************************************************
  15  *
  16  * Last port: simplify/TopologyPreservingSimplifier.java r536 (JTS-1.12+)
  17  *
  18  **********************************************************************
  19  *
  20  * NOTES:
  21  *
  22  **********************************************************************/
  23
  24 #ifndef GEOS_SIMPLIFY_TOPOLOGYPRESERVINGSIMPLIFIER_H
  25 #define GEOS_SIMPLIFY_TOPOLOGYPRESERVINGSIMPLIFIER_H
  26
  27 #include <geos/export.h>
  28 #include <geos/geom/Geometry.h>
  29 #include <geos/simplify/TaggedLinesSimplifier.h>
  30 #include <memory> // for auto_ptr
  31 #include <map>
  32
  33 #ifdef _MSC_VER
  34 #pragma warning(push)
  35 #pragma warning(disable: 4251) // warning C4251: needs to have dll-interface to be used by clients of class
  36 #endif
  37
  38 namespace geos {
  39 namespace simplify { // geos::simplify
  40
  41 /** \brief
  42  *
  43  * Simplifies a geometry, ensuring that
  44  * the result is a valid geometry having the
  45  * same dimension and number of components as the input.
  46  *
  47  * The simplification uses a maximum distance difference algorithm
  48  * similar to the one used in the Douglas-Peucker algorithm.
  49  *
  50  * In particular, if the input is an areal geometry
  51  * ( Polygon or MultiPolygon )
  52  *
  53  *  -  The result has the same number of shells and holes (rings) as the input,
  54  *     in the same order
  55  *  -  The result rings touch at <b>no more</b> than the number of touching point in the input
  56  *     (although they may touch at fewer points)
  57  *
  58  */
  59 class GEOS_DLL TopologyPreservingSimplifier
  60 {
  61
  62 public:
  63
  64         static std::auto_ptr<geom::Geometry> simplify(
  65                         const geom::Geometry* geom,
  66                         double tolerance);
  67
  68         TopologyPreservingSimplifier(const geom::Geometry* geom);
  69
  70         /** \brief
  71          * Sets the distance tolerance for the simplification.
  72          *
  73          * All vertices in the simplified geometry will be within this
  74          * distance of the original geometry.
  75          * The tolerance value must be non-negative.  A tolerance value
  76          * of zero is effectively a no-op.
  77          *
  78          * @param distanceTolerance the approximation tolerance to use
  79          */
  80         void setDistanceTolerance(double tolerance);
  81
  82         std::auto_ptr<geom::Geometry> getResultGeometry();
  83
  84 private:
  85
  86         const geom::Geometry* inputGeom;
  87
  88         std::auto_ptr<TaggedLinesSimplifier> lineSimplifier;
  89
  90 };
  91
  92 } // namespace geos::simplify
  93 } // namespace geos
  94
  95 #ifdef _MSC_VER
  96 #pragma warning(pop)
  97 #endif
  98
  99 #endif // GEOS_SIMPLIFY_TOPOLOGYPRESERVINGSIMPLIFIER_H
 100
 101 /**********************************************************************
 102  * $Log$
 103  * Revision 1.3  2006/04/13 16:04:10  strk
 104  * Made TopologyPreservingSimplifier implementation successfully build
 105  *
 106  * Revision 1.2  2006/04/13 14:25:17  strk
 107  * TopologyPreservingSimplifier initial port
 108  *
 109  **********************************************************************/