Chris@16: // Boost.Geometry (aka GGL, Generic Geometry Library)
Chris@16: 
Chris@16: // Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.
Chris@16: // Copyright (c) 2008-2012 Bruno Lalande, Paris, France.
Chris@16: // Copyright (c) 2009-2012 Mateusz Loskot, London, UK.
Chris@101: // Copyright (c) 2014 Adam Wulkiewicz, Lodz, Poland.
Chris@101: 
Chris@101: // This file was modified by Oracle on 2014, 2015.
Chris@101: // Modifications copyright (c) 2014-2015 Oracle and/or its affiliates.
Chris@101: 
Chris@101: // Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
Chris@16: 
Chris@16: // Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
Chris@16: // (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands.
Chris@16: 
Chris@16: // Use, modification and distribution is subject to the Boost Software License,
Chris@16: // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_GEOMETRY_ALGORITHMS_CENTROID_HPP
Chris@16: #define BOOST_GEOMETRY_ALGORITHMS_CENTROID_HPP
Chris@16: 
Chris@16: 
Chris@16: #include <cstddef>
Chris@16: 
Chris@101: #include <boost/core/ignore_unused.hpp>
Chris@16: #include <boost/range.hpp>
Chris@101: 
Chris@101: #include <boost/variant/apply_visitor.hpp>
Chris@101: #include <boost/variant/static_visitor.hpp>
Chris@101: #include <boost/variant/variant_fwd.hpp>
Chris@16: 
Chris@16: #include <boost/geometry/core/closure.hpp>
Chris@16: #include <boost/geometry/core/cs.hpp>
Chris@16: #include <boost/geometry/core/coordinate_dimension.hpp>
Chris@16: #include <boost/geometry/core/exception.hpp>
Chris@16: #include <boost/geometry/core/exterior_ring.hpp>
Chris@16: #include <boost/geometry/core/interior_rings.hpp>
Chris@16: #include <boost/geometry/core/tag_cast.hpp>
Chris@101: #include <boost/geometry/core/tags.hpp>
Chris@101: #include <boost/geometry/core/point_type.hpp>
Chris@16: 
Chris@101: #include <boost/geometry/geometries/concepts/check.hpp>
Chris@101: 
Chris@101: #include <boost/geometry/algorithms/assign.hpp>
Chris@16: #include <boost/geometry/algorithms/convert.hpp>
Chris@101: #include <boost/geometry/algorithms/detail/interior_iterator.hpp>
Chris@101: #include <boost/geometry/algorithms/detail/point_on_border.hpp>
Chris@16: #include <boost/geometry/algorithms/not_implemented.hpp>
Chris@16: #include <boost/geometry/strategies/centroid.hpp>
Chris@16: #include <boost/geometry/strategies/concepts/centroid_concept.hpp>
Chris@101: #include <boost/geometry/strategies/default_strategy.hpp>
Chris@16: #include <boost/geometry/views/closeable_view.hpp>
Chris@16: 
Chris@16: #include <boost/geometry/util/for_each_coordinate.hpp>
Chris@16: #include <boost/geometry/util/select_coordinate_type.hpp>
Chris@16: 
Chris@101: #include <boost/geometry/algorithms/num_points.hpp>
Chris@101: #include <boost/geometry/multi/algorithms/num_points.hpp>
Chris@101: 
Chris@101: #include <boost/geometry/algorithms/detail/centroid/translating_transformer.hpp>
Chris@16: 
Chris@16: 
Chris@16: namespace boost { namespace geometry
Chris@16: {
Chris@16: 
Chris@16: 
Chris@16: #if ! defined(BOOST_GEOMETRY_CENTROID_NO_THROW)
Chris@16: 
Chris@16: /*!
Chris@16: \brief Centroid Exception
Chris@16: \ingroup centroid
Chris@16: \details The centroid_exception is thrown if the free centroid function is called with
Chris@16:     geometries for which the centroid cannot be calculated. For example: a linestring
Chris@16:     without points, a polygon without points, an empty multi-geometry.
Chris@16: \qbk{
Chris@16: [heading See also]
Chris@16: \* [link geometry.reference.algorithms.centroid the centroid function]
Chris@16: }
Chris@16: 
Chris@16:  */
Chris@16: class centroid_exception : public geometry::exception
Chris@16: {
Chris@16: public:
Chris@16: 
Chris@101:     /*!
Chris@101:     \brief The default constructor
Chris@101:     */
Chris@16:     inline centroid_exception() {}
Chris@16: 
Chris@101:     /*!
Chris@101:     \brief Returns the explanatory string.
Chris@101:     \return Pointer to a null-terminated string with explanatory information.
Chris@101:     */
Chris@16:     virtual char const* what() const throw()
Chris@16:     {
Chris@16:         return "Boost.Geometry Centroid calculation exception";
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: #endif
Chris@16: 
Chris@16: 
Chris@16: #ifndef DOXYGEN_NO_DETAIL
Chris@16: namespace detail { namespace centroid
Chris@16: {
Chris@16: 
Chris@16: struct centroid_point
Chris@16: {
Chris@16:     template<typename Point, typename PointCentroid, typename Strategy>
Chris@16:     static inline void apply(Point const& point, PointCentroid& centroid,
Chris@16:             Strategy const&)
Chris@16:     {
Chris@16:         geometry::convert(point, centroid);
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: template
Chris@16: <
Chris@16:     typename Indexed,
Chris@16:     typename Point,
Chris@101:     std::size_t Dimension = 0,
Chris@101:     std::size_t DimensionCount = dimension<Indexed>::type::value
Chris@16: >
Chris@16: struct centroid_indexed_calculator
Chris@16: {
Chris@16:     typedef typename select_coordinate_type
Chris@16:         <
Chris@16:             Indexed, Point
Chris@16:         >::type coordinate_type;
Chris@16:     static inline void apply(Indexed const& indexed, Point& centroid)
Chris@16:     {
Chris@16:         coordinate_type const c1 = get<min_corner, Dimension>(indexed);
Chris@16:         coordinate_type const c2 = get<max_corner, Dimension>(indexed);
Chris@16:         coordinate_type m = c1 + c2;
Chris@16:         coordinate_type const two = 2;
Chris@16:         m /= two;
Chris@16: 
Chris@16:         set<Dimension>(centroid, m);
Chris@16: 
Chris@16:         centroid_indexed_calculator
Chris@16:             <
Chris@101:                 Indexed, Point, Dimension + 1
Chris@16:             >::apply(indexed, centroid);
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: 
Chris@16: template<typename Indexed, typename Point, std::size_t DimensionCount>
Chris@16: struct centroid_indexed_calculator<Indexed, Point, DimensionCount, DimensionCount>
Chris@16: {
Chris@16:     static inline void apply(Indexed const& , Point& )
Chris@16:     {
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: 
Chris@16: struct centroid_indexed
Chris@16: {
Chris@16:     template<typename Indexed, typename Point, typename Strategy>
Chris@16:     static inline void apply(Indexed const& indexed, Point& centroid,
Chris@16:             Strategy const&)
Chris@16:     {
Chris@16:         centroid_indexed_calculator
Chris@16:             <
Chris@101:                 Indexed, Point
Chris@16:             >::apply(indexed, centroid);
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: 
Chris@16: // There is one thing where centroid is different from e.g. within.
Chris@16: // If the ring has only one point, it might make sense that
Chris@16: // that point is the centroid.
Chris@16: template<typename Point, typename Range>
Chris@16: inline bool range_ok(Range const& range, Point& centroid)
Chris@16: {
Chris@16:     std::size_t const n = boost::size(range);
Chris@16:     if (n > 1)
Chris@16:     {
Chris@16:         return true;
Chris@16:     }
Chris@16:     else if (n <= 0)
Chris@16:     {
Chris@16: #if ! defined(BOOST_GEOMETRY_CENTROID_NO_THROW)
Chris@16:         throw centroid_exception();
Chris@101: #else
Chris@101:         return false;
Chris@16: #endif
Chris@16:     }
Chris@16:     else // if (n == 1)
Chris@16:     {
Chris@16:         // Take over the first point in a "coordinate neutral way"
Chris@16:         geometry::convert(*boost::begin(range), centroid);
Chris@16:         return false;
Chris@16:     }
Chris@101:     //return true; // unreachable
Chris@16: }
Chris@16: 
Chris@16: /*!
Chris@101:     \brief Calculate the centroid of a Ring or a Linestring.
Chris@16: */
Chris@16: template <closure_selector Closure>
Chris@16: struct centroid_range_state
Chris@16: {
Chris@101:     template<typename Ring, typename PointTransformer, typename Strategy>
Chris@16:     static inline void apply(Ring const& ring,
Chris@101:                              PointTransformer const& transformer,
Chris@101:                              Strategy const& strategy,
Chris@101:                              typename Strategy::state_type& state)
Chris@16:     {
Chris@101:         boost::ignore_unused(strategy);
Chris@101: 
Chris@101:         typedef typename geometry::point_type<Ring const>::type point_type;
Chris@16:         typedef typename closeable_view<Ring const, Closure>::type view_type;
Chris@16: 
Chris@16:         typedef typename boost::range_iterator<view_type const>::type iterator_type;
Chris@16: 
Chris@16:         view_type view(ring);
Chris@16:         iterator_type it = boost::begin(view);
Chris@16:         iterator_type end = boost::end(view);
Chris@16: 
Chris@101:         typename PointTransformer::result_type
Chris@101:             previous_pt = transformer.apply(*it);
Chris@101: 
Chris@101:         for ( ++it ; it != end ; ++it)
Chris@16:         {
Chris@101:             typename PointTransformer::result_type
Chris@101:                 pt = transformer.apply(*it);
Chris@101: 
Chris@101:             strategy.apply(static_cast<point_type const&>(previous_pt),
Chris@101:                            static_cast<point_type const&>(pt),
Chris@101:                            state);
Chris@101:             
Chris@101:             previous_pt = pt;
Chris@16:         }
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: template <closure_selector Closure>
Chris@16: struct centroid_range
Chris@16: {
Chris@16:     template<typename Range, typename Point, typename Strategy>
Chris@101:     static inline bool apply(Range const& range, Point& centroid,
Chris@101:                              Strategy const& strategy)
Chris@16:     {
Chris@16:         if (range_ok(range, centroid))
Chris@16:         {
Chris@101:             // prepare translation transformer
Chris@101:             translating_transformer<Range> transformer(*boost::begin(range));
Chris@101:             
Chris@16:             typename Strategy::state_type state;
Chris@101:             centroid_range_state<Closure>::apply(range, transformer,
Chris@101:                                                  strategy, state);
Chris@101:             
Chris@101:             if ( strategy.result(state, centroid) )
Chris@101:             {
Chris@101:                 // translate the result back
Chris@101:                 transformer.apply_reverse(centroid);
Chris@101:                 return true;
Chris@101:             }
Chris@16:         }
Chris@101: 
Chris@101:         return false;
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: 
Chris@16: /*!
Chris@16:     \brief Centroid of a polygon.
Chris@16:     \note Because outer ring is clockwise, inners are counter clockwise,
Chris@16:     triangle approach is OK and works for polygons with rings.
Chris@16: */
Chris@16: struct centroid_polygon_state
Chris@16: {
Chris@101:     template<typename Polygon, typename PointTransformer, typename Strategy>
Chris@16:     static inline void apply(Polygon const& poly,
Chris@101:                              PointTransformer const& transformer,
Chris@101:                              Strategy const& strategy,
Chris@101:                              typename Strategy::state_type& state)
Chris@16:     {
Chris@16:         typedef typename ring_type<Polygon>::type ring_type;
Chris@16:         typedef centroid_range_state<geometry::closure<ring_type>::value> per_ring;
Chris@16: 
Chris@101:         per_ring::apply(exterior_ring(poly), transformer, strategy, state);
Chris@16: 
Chris@101:         typename interior_return_type<Polygon const>::type
Chris@101:             rings = interior_rings(poly);
Chris@101: 
Chris@101:         for (typename detail::interior_iterator<Polygon const>::type
Chris@101:                 it = boost::begin(rings); it != boost::end(rings); ++it)
Chris@16:         {
Chris@101:             per_ring::apply(*it, transformer, strategy, state);
Chris@16:         }
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: struct centroid_polygon
Chris@16: {
Chris@16:     template<typename Polygon, typename Point, typename Strategy>
Chris@101:     static inline bool apply(Polygon const& poly, Point& centroid,
Chris@101:                              Strategy const& strategy)
Chris@16:     {
Chris@16:         if (range_ok(exterior_ring(poly), centroid))
Chris@16:         {
Chris@101:             // prepare translation transformer
Chris@101:             translating_transformer<Polygon>
Chris@101:                 transformer(*boost::begin(exterior_ring(poly)));
Chris@101:             
Chris@16:             typename Strategy::state_type state;
Chris@101:             centroid_polygon_state::apply(poly, transformer, strategy, state);
Chris@101:             
Chris@101:             if ( strategy.result(state, centroid) )
Chris@101:             {
Chris@101:                 // translate the result back
Chris@101:                 transformer.apply_reverse(centroid);
Chris@101:                 return true;
Chris@101:             }
Chris@101:         }
Chris@101: 
Chris@101:         return false;
Chris@101:     }
Chris@101: };
Chris@101: 
Chris@101: 
Chris@101: /*!
Chris@101:     \brief Building block of a multi-point, to be used as Policy in the
Chris@101:         more generec centroid_multi
Chris@101: */
Chris@101: struct centroid_multi_point_state
Chris@101: {
Chris@101:     template <typename Point, typename PointTransformer, typename Strategy>
Chris@101:     static inline void apply(Point const& point,
Chris@101:                              PointTransformer const& transformer,
Chris@101:                              Strategy const& strategy,
Chris@101:                              typename Strategy::state_type& state)
Chris@101:     {
Chris@101:         boost::ignore_unused(strategy);
Chris@101:         strategy.apply(static_cast<Point const&>(transformer.apply(point)),
Chris@101:                        state);
Chris@101:     }
Chris@101: };
Chris@101: 
Chris@101: 
Chris@101: /*!
Chris@101:     \brief Generic implementation which calls a policy to calculate the
Chris@101:         centroid of the total of its single-geometries
Chris@101:     \details The Policy is, in general, the single-version, with state. So
Chris@101:         detail::centroid::centroid_polygon_state is used as a policy for this
Chris@101:         detail::centroid::centroid_multi
Chris@101: 
Chris@101: */
Chris@101: template <typename Policy>
Chris@101: struct centroid_multi
Chris@101: {
Chris@101:     template <typename Multi, typename Point, typename Strategy>
Chris@101:     static inline bool apply(Multi const& multi,
Chris@101:                              Point& centroid,
Chris@101:                              Strategy const& strategy)
Chris@101:     {
Chris@101: #if ! defined(BOOST_GEOMETRY_CENTROID_NO_THROW)
Chris@101:         // If there is nothing in any of the ranges, it is not possible
Chris@101:         // to calculate the centroid
Chris@101:         if (geometry::num_points(multi) == 0)
Chris@101:         {
Chris@101:             throw centroid_exception();
Chris@101:         }
Chris@101: #endif
Chris@101: 
Chris@101:         // prepare translation transformer
Chris@101:         translating_transformer<Multi> transformer(multi);
Chris@101: 
Chris@101:         typename Strategy::state_type state;
Chris@101: 
Chris@101:         for (typename boost::range_iterator<Multi const>::type
Chris@101:                 it = boost::begin(multi);
Chris@101:             it != boost::end(multi);
Chris@101:             ++it)
Chris@101:         {
Chris@101:             Policy::apply(*it, transformer, strategy, state);
Chris@101:         }
Chris@101: 
Chris@101:         if ( strategy.result(state, centroid) )
Chris@101:         {
Chris@101:             // translate the result back
Chris@101:             transformer.apply_reverse(centroid);
Chris@101:             return true;
Chris@101:         }
Chris@101:         
Chris@101:         return false;
Chris@101:     }
Chris@101: };
Chris@101: 
Chris@101: 
Chris@101: template <typename Algorithm>
Chris@101: struct centroid_linear_areal
Chris@101: {
Chris@101:     template <typename Geometry, typename Point, typename Strategy>
Chris@101:     static inline void apply(Geometry const& geom,
Chris@101:                              Point& centroid,
Chris@101:                              Strategy const& strategy)
Chris@101:     {
Chris@101:         if ( ! Algorithm::apply(geom, centroid, strategy) )
Chris@101:         {
Chris@101:             geometry::point_on_border(centroid, geom);
Chris@16:         }
Chris@16:     }
Chris@16: };
Chris@16: 
Chris@16: 
Chris@16: }} // namespace detail::centroid
Chris@16: #endif // DOXYGEN_NO_DETAIL
Chris@16: 
Chris@16: 
Chris@16: #ifndef DOXYGEN_NO_DISPATCH
Chris@16: namespace dispatch
Chris@16: {
Chris@16: 
Chris@16: template
Chris@16: <
Chris@16:     typename Geometry,
Chris@16:     typename Tag = typename tag<Geometry>::type
Chris@16: >
Chris@16: struct centroid: not_implemented<Tag>
Chris@16: {};
Chris@16: 
Chris@16: template <typename Geometry>
Chris@16: struct centroid<Geometry, point_tag>
Chris@16:     : detail::centroid::centroid_point
Chris@16: {};
Chris@16: 
Chris@16: template <typename Box>
Chris@16: struct centroid<Box, box_tag>
Chris@16:     : detail::centroid::centroid_indexed
Chris@16: {};
Chris@16: 
Chris@16: template <typename Segment>
Chris@16: struct centroid<Segment, segment_tag>
Chris@16:     : detail::centroid::centroid_indexed
Chris@16: {};
Chris@16: 
Chris@16: template <typename Ring>
Chris@16: struct centroid<Ring, ring_tag>
Chris@101:     : detail::centroid::centroid_linear_areal
Chris@101:         <
Chris@101:             detail::centroid::centroid_range<geometry::closure<Ring>::value>
Chris@101:         >
Chris@16: {};
Chris@16: 
Chris@16: template <typename Linestring>
Chris@16: struct centroid<Linestring, linestring_tag>
Chris@101:     : detail::centroid::centroid_linear_areal
Chris@101:         <
Chris@101:             detail::centroid::centroid_range<closed>
Chris@101:         >
Chris@101: {};
Chris@16: 
Chris@16: template <typename Polygon>
Chris@16: struct centroid<Polygon, polygon_tag>
Chris@101:     : detail::centroid::centroid_linear_areal
Chris@101:         <
Chris@101:             detail::centroid::centroid_polygon
Chris@101:         >
Chris@101: {};
Chris@101: 
Chris@101: template <typename MultiLinestring>
Chris@101: struct centroid<MultiLinestring, multi_linestring_tag>
Chris@101:     : detail::centroid::centroid_linear_areal
Chris@101:         <
Chris@101:             detail::centroid::centroid_multi
Chris@101:             <
Chris@101:                 detail::centroid::centroid_range_state<closed>
Chris@101:             >
Chris@101:         >
Chris@101: {};
Chris@101: 
Chris@101: template <typename MultiPolygon>
Chris@101: struct centroid<MultiPolygon, multi_polygon_tag>
Chris@101:     : detail::centroid::centroid_linear_areal
Chris@101:         <
Chris@101:             detail::centroid::centroid_multi
Chris@101:             <
Chris@101:                 detail::centroid::centroid_polygon_state
Chris@101:             >
Chris@101:         >
Chris@101: {};
Chris@101: 
Chris@101: template <typename MultiPoint>
Chris@101: struct centroid<MultiPoint, multi_point_tag>
Chris@101:     : detail::centroid::centroid_multi
Chris@101:         <
Chris@101:             detail::centroid::centroid_multi_point_state
Chris@101:         >
Chris@101: {};
Chris@101: 
Chris@16: 
Chris@16: } // namespace dispatch
Chris@16: #endif // DOXYGEN_NO_DISPATCH
Chris@16: 
Chris@16: 
Chris@101: namespace resolve_strategy {
Chris@101: 
Chris@101: template <typename Geometry>
Chris@101: struct centroid
Chris@101: {
Chris@101:     template <typename Point, typename Strategy>
Chris@101:     static inline void apply(Geometry const& geometry, Point& out, Strategy const& strategy)
Chris@101:     {
Chris@101:         dispatch::centroid<Geometry>::apply(geometry, out, strategy);
Chris@101:     }
Chris@101: 
Chris@101:     template <typename Point>
Chris@101:     static inline void apply(Geometry const& geometry, Point& out, default_strategy)
Chris@101:     {
Chris@101:         typedef typename strategy::centroid::services::default_strategy
Chris@101:         <
Chris@101:             typename cs_tag<Geometry>::type,
Chris@101:             typename tag_cast
Chris@101:                 <
Chris@101:                     typename tag<Geometry>::type,
Chris@101:                     pointlike_tag,
Chris@101:                     linear_tag,
Chris@101:                     areal_tag
Chris@101:                 >::type,
Chris@101:             dimension<Geometry>::type::value,
Chris@101:             Point,
Chris@101:             Geometry
Chris@101:         >::type strategy_type;
Chris@101: 
Chris@101:         dispatch::centroid<Geometry>::apply(geometry, out, strategy_type());
Chris@101:     }
Chris@101: };
Chris@101: 
Chris@101: } // namespace resolve_strategy
Chris@101: 
Chris@101: 
Chris@101: namespace resolve_variant {
Chris@101: 
Chris@101: template <typename Geometry>
Chris@101: struct centroid
Chris@101: {
Chris@101:     template <typename Point, typename Strategy>
Chris@101:     static inline void apply(Geometry const& geometry, Point& out, Strategy const& strategy)
Chris@101:     {
Chris@101:         concept::check_concepts_and_equal_dimensions<Point, Geometry const>();
Chris@101:         resolve_strategy::centroid<Geometry>::apply(geometry, out, strategy);
Chris@101:     }
Chris@101: };
Chris@101: 
Chris@101: template <BOOST_VARIANT_ENUM_PARAMS(typename T)>
Chris@101: struct centroid<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)> >
Chris@101: {
Chris@101:     template <typename Point, typename Strategy>
Chris@101:     struct visitor: boost::static_visitor<void>
Chris@101:     {
Chris@101:         Point& m_out;
Chris@101:         Strategy const& m_strategy;
Chris@101: 
Chris@101:         visitor(Point& out, Strategy const& strategy)
Chris@101:         : m_out(out), m_strategy(strategy)
Chris@101:         {}
Chris@101: 
Chris@101:         template <typename Geometry>
Chris@101:         void operator()(Geometry const& geometry) const
Chris@101:         {
Chris@101:             centroid<Geometry>::apply(geometry, m_out, m_strategy);
Chris@101:         }
Chris@101:     };
Chris@101: 
Chris@101:     template <typename Point, typename Strategy>
Chris@101:     static inline void
Chris@101:     apply(boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)> const& geometry,
Chris@101:           Point& out,
Chris@101:           Strategy const& strategy)
Chris@101:     {
Chris@101:         boost::apply_visitor(visitor<Point, Strategy>(out, strategy), geometry);
Chris@101:     }
Chris@101: };
Chris@101: 
Chris@101: } // namespace resolve_variant
Chris@101: 
Chris@101: 
Chris@16: /*!
Chris@16: \brief \brief_calc{centroid} \brief_strategy
Chris@16: \ingroup centroid
Chris@16: \details \details_calc{centroid,geometric center (or: center of mass)}. \details_strategy_reasons
Chris@16: \tparam Geometry \tparam_geometry
Chris@16: \tparam Point \tparam_point
Chris@16: \tparam Strategy \tparam_strategy{Centroid}
Chris@16: \param geometry \param_geometry
Chris@16: \param c \param_point \param_set{centroid}
Chris@16: \param strategy \param_strategy{centroid}
Chris@16: 
Chris@16: \qbk{distinguish,with strategy}
Chris@16: \qbk{[include reference/algorithms/centroid.qbk]}
Chris@16: \qbk{[include reference/algorithms/centroid_strategies.qbk]}
Chris@16: }
Chris@16: 
Chris@16: */
Chris@16: template<typename Geometry, typename Point, typename Strategy>
Chris@16: inline void centroid(Geometry const& geometry, Point& c,
Chris@16:         Strategy const& strategy)
Chris@16: {
Chris@101:     resolve_variant::centroid<Geometry>::apply(geometry, c, strategy);
Chris@16: }
Chris@16: 
Chris@16: 
Chris@16: /*!
Chris@16: \brief \brief_calc{centroid}
Chris@16: \ingroup centroid
Chris@16: \details \details_calc{centroid,geometric center (or: center of mass)}. \details_default_strategy
Chris@16: \tparam Geometry \tparam_geometry
Chris@16: \tparam Point \tparam_point
Chris@16: \param geometry \param_geometry
Chris@16: \param c The calculated centroid will be assigned to this point reference
Chris@16: 
Chris@16: \qbk{[include reference/algorithms/centroid.qbk]}
Chris@16: \qbk{
Chris@16: [heading Example]
Chris@16: [centroid]
Chris@16: [centroid_output]
Chris@16: }
Chris@16:  */
Chris@16: template<typename Geometry, typename Point>
Chris@16: inline void centroid(Geometry const& geometry, Point& c)
Chris@16: {
Chris@101:     centroid(geometry, c, default_strategy());
Chris@16: }
Chris@16: 
Chris@16: 
Chris@16: /*!
Chris@16: \brief \brief_calc{centroid}
Chris@16: \ingroup centroid
Chris@16: \details \details_calc{centroid,geometric center (or: center of mass)}. \details_return{centroid}.
Chris@16: \tparam Point \tparam_point
Chris@16: \tparam Geometry \tparam_geometry
Chris@16: \param geometry \param_geometry
Chris@16: \return \return_calc{centroid}
Chris@16: 
Chris@16: \qbk{[include reference/algorithms/centroid.qbk]}
Chris@16:  */
Chris@16: template<typename Point, typename Geometry>
Chris@16: inline Point return_centroid(Geometry const& geometry)
Chris@16: {
Chris@16:     Point c;
Chris@16:     centroid(geometry, c);
Chris@16:     return c;
Chris@16: }
Chris@16: 
Chris@16: /*!
Chris@16: \brief \brief_calc{centroid} \brief_strategy
Chris@16: \ingroup centroid
Chris@16: \details \details_calc{centroid,geometric center (or: center of mass)}. \details_return{centroid}. \details_strategy_reasons
Chris@16: \tparam Point \tparam_point
Chris@16: \tparam Geometry \tparam_geometry
Chris@16: \tparam Strategy \tparam_strategy{centroid}
Chris@16: \param geometry \param_geometry
Chris@16: \param strategy \param_strategy{centroid}
Chris@16: \return \return_calc{centroid}
Chris@16: 
Chris@16: \qbk{distinguish,with strategy}
Chris@16: \qbk{[include reference/algorithms/centroid.qbk]}
Chris@16: \qbk{[include reference/algorithms/centroid_strategies.qbk]}
Chris@16:  */
Chris@16: template<typename Point, typename Geometry, typename Strategy>
Chris@16: inline Point return_centroid(Geometry const& geometry, Strategy const& strategy)
Chris@16: {
Chris@16:     Point c;
Chris@16:     centroid(geometry, c, strategy);
Chris@16:     return c;
Chris@16: }
Chris@16: 
Chris@16: 
Chris@16: }} // namespace boost::geometry
Chris@16: 
Chris@16: 
Chris@16: #endif // BOOST_GEOMETRY_ALGORITHMS_CENTROID_HPP