ceph/src/boost/libs/geometry/doc/src/examples/algorithms/is_valid_failure.cpp

   1 // Boost.Geometry (aka GGL, Generic Geometry Library)
   2 // QuickBook Example
   3
   4 // Copyright (c) 2015, Oracle and/or its affiliates
   5
   6 // Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
   7
   8 // Licensed under the Boost Software License version 1.0.
   9 // http://www.boost.org/users/license.html
  10
  11 //[is_valid_failure
  12 //` Checks whether a geometry is valid and, if not valid, checks if it could be fixed by bg::correct; if so bg::correct is called on the geometry
  13
  14 #include <iostream>
  15
  16 #include <boost/geometry.hpp>
  17 #include <boost/geometry/geometries/point_xy.hpp>
  18 #include <boost/geometry/geometries/polygon.hpp>
  19 /*<-*/ #include "create_svg_one.hpp" /*->*/
  20
  21 int main()
  22 {
  23     typedef boost::geometry::model::d2::point_xy<double> point_type;
  24     typedef boost::geometry::model::polygon<point_type> polygon_type;
  25
  26     polygon_type poly;
  27     boost::geometry::read_wkt("POLYGON((0 0,0 10,10 10,10 0),(0 0,9 2,9 1,0 0),(0 0,2 9,1 9,0 0))", poly);
  28
  29     std::cout << "original geometry: " << boost::geometry::dsv(poly) << std::endl;
  30     boost::geometry::validity_failure_type failure;
  31     bool valid = boost::geometry::is_valid(poly, failure);
  32
  33     // if the invalidity is only due to lack of closing points and/or wrongly oriented rings, then bg::correct can fix it
  34     bool could_be_fixed = (failure == boost::geometry::failure_not_closed
  35                            || boost::geometry::failure_wrong_orientation);
  36     std::cout << "is valid? " << (valid ? "yes" : "no") << std::endl;
  37     if (! valid)
  38     {
  39         std::cout << "can boost::geometry::correct remedy invalidity? " << (could_be_fixed ? "possibly yes" : "no") << std::endl;
  40         if (could_be_fixed)
  41         {
  42             boost::geometry::correct(poly);
  43             std::cout << "after correction: " << (boost::geometry::is_valid(poly) ? "valid" : "still invalid") << std::endl;
  44             std::cout << "corrected geometry: " << boost::geometry::dsv(poly) << std::endl;
  45         }
  46     }
  47     /*<-*/ create_svg("is_valid_failure_example.svg", poly); /*->*/
  48     return 0;
  49 }
  50
  51 //]
  52
  53 //[is_valid_failure_output
  54 /*`
  55 Output:
  56 [pre
  57 original geometry: (((0, 0), (0, 10), (10, 10), (10, 0)), ((0, 0), (9, 2), (9, 1), (0, 0)), ((0, 0), (2, 9), (1, 9), (0, 0)))
  58 is valid? no
  59 can boost::geometry::correct remedy invalidity? possibly yes
  60 after correction: valid
  61 corrected geometry: (((0, 0), (0, 10), (10, 10), (10, 0), (0, 0)), ((0, 0), (9, 1), (9, 2), (0, 0)), ((0, 0), (2, 9), (1, 9), (0, 0)))
  62
  63 [$img/algorithms/is_valid_failure_example.png]
  64
  65 ]
  66
  67 */
  68 //]