1 /**********************************************************************
2  *
3  * GEOS - Geometry Engine Open Source
4  * http://geos.osgeo.org
5  *
6  * Copyright (C) 2006 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 Licence as published
10  * by the Free Software Foundation.
11  * See the COPYING file for more information.
12  *
13  **********************************************************************
14  *
15  * Last port: simplify/DouglasPeuckerSimplifier.java rev. 1.5 (JTS-1.7)
16  *
17  **********************************************************************/
18 
19 #ifndef GEOS_SIMPLIFY_DOUBGLASPEUCKERSIMPLIFIER_H
20 #define GEOS_SIMPLIFY_DOUBGLASPEUCKERSIMPLIFIER_H
21 
22 #include <geos/export.h>
23 #include <memory> // for unique_ptr
24 
25 // Forward declarations
26 namespace geos {
27 namespace geom {
28 class Geometry;
29 }
30 }
31 
32 namespace geos {
33 namespace simplify { // geos::simplify
34 
35 
36 /** \brief
37  * Simplifies a Geometry using the standard Douglas-Peucker algorithm.
38  *
39  * Ensures that any polygonal geometries returned are valid.
40  * Simple lines are not guaranteed to remain simple after simplification.
41  *
42  * Note that in general D-P does not preserve topology -
43  * e.g. polygons can be split, collapse to lines or disappear
44  * holes can be created or disappear,
45  * and lines can cross.
46  * To simplify geometry while preserving topology use TopologyPreservingSimplifier.
47  * (However, using D-P is significantly faster).
48  *
49  */
50 class GEOS_DLL DouglasPeuckerSimplifier {
51 
52 public:
53 
54     static std::unique_ptr<geom::Geometry> simplify(
55         const geom::Geometry* geom,
56         double tolerance);
57 
58     DouglasPeuckerSimplifier(const geom::Geometry* geom);
59 
60     /** \brief
61      * Sets the distance tolerance for the simplification.
62      *
63      * All vertices in the simplified geometry will be within this
64      * distance of the original geometry.
65      * The tolerance value must be non-negative.  A tolerance value
66      * of zero is effectively a no-op.
67      *
68      * @param tolerance the approximation tolerance to use
69      */
70     void setDistanceTolerance(double tolerance);
71 
72     std::unique_ptr<geom::Geometry> getResultGeometry();
73 
74 
75 private:
76 
77     const geom::Geometry* inputGeom;
78 
79     double distanceTolerance;
80 };
81 
82 
83 } // namespace geos::simplify
84 } // namespace geos
85 
86 #endif // GEOS_SIMPLIFY_DOUBGLASPEUCKERSIMPLIFIER_H
87