1 // Boost.Geometry (aka GGL, Generic Geometry Library)
2 // QuickBook Example
3
4 // Copyright (c) 2011-2012 Barend Gehrels, Amsterdam, the Netherlands.
5
6 // Use, modification and distribution is subject to the Boost Software License,
7 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
8 // http://www.boost.org/LICENSE_1_0.txt)
9
10 //[for_each_point
11 //` Convenient usage of for_each_point, rounding all points of a geometry
12
13 #include <iostream>
14
15 #include <boost/geometry.hpp>
16 #include <boost/geometry/geometries/point_xy.hpp>
17 #include <boost/geometry/geometries/polygon.hpp>
18
19
20
21 template <typename Point>
22 class round_coordinates
23 {
24 private :
25 typedef typename boost::geometry::coordinate_type<Point>::type coordinate_type;
26 coordinate_type factor;
27
round(coordinate_type value)28 inline coordinate_type round(coordinate_type value)
29 {
30 return floor(0.5 + (value / factor)) * factor;
31 }
32
33 public :
round_coordinates(coordinate_type f)34 round_coordinates(coordinate_type f)
35 : factor(f)
36 {}
37
operator ()(Point & p)38 inline void operator()(Point& p)
39 {
40 using boost::geometry::get;
41 using boost::geometry::set;
42 set<0>(p, round(get<0>(p)));
43 set<1>(p, round(get<1>(p)));
44 }
45 };
46
47
main()48 int main()
49 {
50 typedef boost::geometry::model::d2::point_xy<double> point;
51 boost::geometry::model::polygon<point> poly;
52 boost::geometry::read_wkt("POLYGON((0 0,1.123 9.987,8.876 2.234,0 0),(3.345 4.456,7.654 8.765,9.123 5.432,3.345 4.456))", poly);
53 boost::geometry::for_each_point(poly, round_coordinates<point>(0.1));
54 std::cout << "Rounded: " << boost::geometry::wkt(poly) << std::endl;
55 return 0;
56 }
57
58 //]
59
60
61 //[for_each_point_output
62 /*`
63 Output:
64 [pre
65 Rounded: POLYGON((0 0,1.1 10,8.9 2.2,0 0),(3.3 4.5,7.7 8.8,9.1 5.4,3.3 4.5))
66 ]
67 */
68 //]
69