include/geos/simplify/TaggedLineStringSimplifier.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/TaggedLineStringSimplifier.java r536 (JTS-1.12+)
  17  *
  18  **********************************************************************
  19  *
  20  * NOTES: This class can be optimized to work with vector<Coordinate*>
  21  *        rather then with CoordinateSequence
  22  *
  23  **********************************************************************/
  24
  25 #ifndef GEOS_SIMPLIFY_TAGGEDLINESTRINGSIMPLIFIER_H
  26 #define GEOS_SIMPLIFY_TAGGEDLINESTRINGSIMPLIFIER_H
  27
  28 #include <geos/export.h>
  29 #include <cstddef>
  30 #include <vector>
  31 #include <memory>
  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 // Forward declarations
  39 namespace geos {
  40         namespace algorithm {
  41                 class LineIntersector;
  42         }
  43         namespace geom {
  44                 class CoordinateSequence;
  45                 class LineSegment;
  46         }
  47         namespace simplify {
  48                 class TaggedLineSegment;
  49                 class TaggedLineString;
  50                 class LineSegmentIndex;
  51         }
  52 }
  53
  54 namespace geos {
  55 namespace simplify { // geos::simplify
  56
  57
  58 /** \brief
  59  * Simplifies a TaggedLineString, preserving topology
  60  * (in the sense that no new intersections are introduced).
  61  * Uses the recursive Douglas-Peucker algorithm.
  62  *
  63  */
  64 class GEOS_DLL TaggedLineStringSimplifier {
  65
  66 public:
  67
  68         TaggedLineStringSimplifier(LineSegmentIndex* inputIndex,
  69                 LineSegmentIndex* outputIndex);
  70
  71         /** \brief
  72          * Sets the distance tolerance for the simplification.
  73          *
  74          * All vertices in the simplified geometry will be within this
  75          * distance of the original geometry.
  76          *
  77          * @param d the approximation tolerance to use
  78          */
  79         void setDistanceTolerance(double d);
  80
  81         /**
  82          * Simplifies the given {@link TaggedLineString}
  83          * using the distance tolerance specified.
  84          *
  85          * @param line the linestring to simplify
  86          */
  87         void simplify(TaggedLineString* line);
  88
  89
  90 private:
  91
  92         // externally owned
  93         LineSegmentIndex* inputIndex;
  94
  95         // externally owned
  96         LineSegmentIndex* outputIndex;
  97
  98         std::auto_ptr<algorithm::LineIntersector> li;
  99
 100         /// non-const as segments are possibly added to it
 101         TaggedLineString* line;
 102
 103         const geom::CoordinateSequence* linePts;
 104
 105         double distanceTolerance;
 106
 107         void simplifySection(std::size_t i, std::size_t j,
 108                         std::size_t depth);
 109
 110         static std::size_t findFurthestPoint(
 111                         const geom::CoordinateSequence* pts,
 112                         std::size_t i, std::size_t j,
 113                         double& maxDistance);
 114
 115         bool hasBadIntersection(const TaggedLineString* parentLine,
 116                        const std::vector<std::size_t>& sectionIndex,
 117                        const geom::LineSegment& candidateSeg);
 118
 119         bool hasBadInputIntersection(const TaggedLineString* parentLine,
 120                        const std::vector<std::size_t>& sectionIndex,
 121                        const geom::LineSegment& candidateSeg);
 122
 123         bool hasBadOutputIntersection(const geom::LineSegment& candidateSeg);
 124
 125         bool hasInteriorIntersection(const geom::LineSegment& seg0,
 126                         const geom::LineSegment& seg1) const;
 127
 128         std::auto_ptr<TaggedLineSegment> flatten(
 129                         std::size_t start, std::size_t end);
 130
 131         /** \brief
 132          * Tests whether a segment is in a section of a TaggedLineString
 133          *
 134          * @param line
 135          * @param sectionIndex
 136          * @param seg
 137          * @return
 138          */
 139         static bool isInLineSection(
 140                 const TaggedLineString* parentLine,
 141                 const std::vector<std::size_t>& sectionIndex,
 142                 const TaggedLineSegment* seg);
 143
 144         /** \brief
 145          * Remove the segs in the section of the line
 146          *
 147          * @param line
 148          * @param pts
 149          * @param sectionStartIndex
 150          * @param sectionEndIndex
 151          */
 152         void remove(const TaggedLineString* line,
 153                         std::size_t start,
 154                         std::size_t end);
 155
 156 };
 157
 158 inline void
 159 TaggedLineStringSimplifier::setDistanceTolerance(double d)
 160 {
 161         distanceTolerance = d;
 162 }
 163
 164 } // namespace geos::simplify
 165 } // namespace geos
 166
 167 #ifdef _MSC_VER
 168 #pragma warning(pop)
 169 #endif
 170
 171 #endif // GEOS_SIMPLIFY_TAGGEDLINESTRINGSIMPLIFIER_H
 172