boost/libs/geometry/doc/src/examples/algorithms/buffer_with_strategies.cpp

// Boost.Geometry (aka GGL, Generic Geometry Library)
// QuickBook Example

// Copyright (c) 2013, 2014 Barend Gehrels, Amsterdam, the Netherlands.

// Use, modification and distribution is subject to the Boost Software License,
// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)

//[buffer_with_strategies
//` Shows how the buffer algorithm can be used to create a buffer of a linestring

#include <boost/geometry.hpp>
#include <boost/geometry/geometries/point_xy.hpp>
#include <boost/geometry/geometries/geometries.hpp>
/*<-*/ #include "../examples_utils/create_svg_buffer.hpp" /*->*/

int main()
{
    typedef double coordinate_type;
    typedef boost::geometry::model::d2::point_xy<coordinate_type> point;
    typedef boost::geometry::model::polygon<point> polygon;

    // Declare strategies
    const double buffer_distance = 1.0;
    const int points_per_circle = 36;
    boost::geometry::strategy::buffer::distance_symmetric<coordinate_type> distance_strategy(buffer_distance);
    boost::geometry::strategy::buffer::join_round join_strategy(points_per_circle);
    boost::geometry::strategy::buffer::end_round end_strategy(points_per_circle);
    boost::geometry::strategy::buffer::point_circle circle_strategy(points_per_circle);
    boost::geometry::strategy::buffer::side_straight side_strategy;

    // Declare output
    boost::geometry::model::multi_polygon<polygon> result;

    // Declare/fill a linestring
    boost::geometry::model::linestring<point> ls;
    boost::geometry::read_wkt("LINESTRING(0 0,4 5,7 4,10 6)", ls);

    // Create the buffer of a linestring
    boost::geometry::buffer(ls, result,
                distance_strategy, side_strategy,
                join_strategy, end_strategy, circle_strategy);
    /*<-*/ create_svg_buffer("buffer_linestring.svg", ls, result); /*->*/

    // Declare/fill a multi point
    boost::geometry::model::multi_point<point> mp;
    boost::geometry::read_wkt("MULTIPOINT((3 3),(4 4),(6 2))", mp);

    // Create the buffer of a multi point
    boost::geometry::buffer(mp, result,
                distance_strategy, side_strategy,
                join_strategy, end_strategy, circle_strategy);
    /*<-*/ create_svg_buffer("buffer_multi_point.svg", mp, result); /*->*/

    // Declare/fill a multi_polygon
    boost::geometry::model::multi_polygon<polygon> mpol;
    boost::geometry::read_wkt("MULTIPOLYGON(((0 1,2 5,5 3,0 1)),((1 1,5 2,5 0,1 1)))", mpol);

    // Create the buffer of a multi polygon
    boost::geometry::buffer(mpol, result,
                distance_strategy, side_strategy,
                join_strategy, end_strategy, circle_strategy);
    /*<-*/ create_svg_buffer("buffer_multi_polygon.svg", mpol, result); /*->*/

    return 0;
}

//]