| // Boost.Geometry (aka GGL, Generic Geometry Library) |
| |
| // Copyright (c) 2007-2011 Barend Gehrels, Amsterdam, the Netherlands. |
| // Copyright (c) 2008-2011 Bruno Lalande, Paris, France. |
| // Copyright (c) 2009-2011 Mateusz Loskot, London, UK. |
| |
| // Parts of Boost.Geometry are redesigned from Geodan's Geographic Library |
| // (geolib/GGL), copyright (c) 1995-2010 Geodan, 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) |
| |
| #ifndef BOOST_GEOMETRY_ALGORITHMS_AREA_HPP |
| #define BOOST_GEOMETRY_ALGORITHMS_AREA_HPP |
| |
| #include <boost/concept_check.hpp> |
| #include <boost/mpl/if.hpp> |
| #include <boost/range/functions.hpp> |
| #include <boost/range/metafunctions.hpp> |
| |
| |
| #include <boost/geometry/core/closure.hpp> |
| #include <boost/geometry/core/exterior_ring.hpp> |
| #include <boost/geometry/core/interior_rings.hpp> |
| #include <boost/geometry/core/point_order.hpp> |
| #include <boost/geometry/core/ring_type.hpp> |
| |
| #include <boost/geometry/geometries/concepts/check.hpp> |
| |
| #include <boost/geometry/algorithms/detail/calculate_null.hpp> |
| #include <boost/geometry/algorithms/detail/calculate_sum.hpp> |
| |
| #include <boost/geometry/strategies/area.hpp> |
| #include <boost/geometry/strategies/default_area_result.hpp> |
| |
| #include <boost/geometry/strategies/concepts/area_concept.hpp> |
| |
| #include <boost/geometry/util/math.hpp> |
| #include <boost/geometry/util/order_as_direction.hpp> |
| #include <boost/geometry/views/closeable_view.hpp> |
| #include <boost/geometry/views/reversible_view.hpp> |
| |
| |
| namespace boost { namespace geometry |
| { |
| |
| #ifndef DOXYGEN_NO_DETAIL |
| namespace detail { namespace area |
| { |
| |
| template<typename Box, typename Strategy> |
| struct box_area |
| { |
| typedef typename coordinate_type<Box>::type return_type; |
| |
| static inline return_type apply(Box const& box, Strategy const&) |
| { |
| // Currently only works for 2D Cartesian boxes |
| assert_dimension<Box, 2>(); |
| |
| return_type const dx = get<max_corner, 0>(box) |
| - get<min_corner, 0>(box); |
| return_type const dy = get<max_corner, 1>(box) |
| - get<min_corner, 1>(box); |
| |
| return dx * dy; |
| } |
| }; |
| |
| |
| template |
| < |
| typename Ring, |
| iterate_direction Direction, |
| closure_selector Closure, |
| typename Strategy |
| > |
| struct ring_area |
| { |
| BOOST_CONCEPT_ASSERT( (geometry::concept::AreaStrategy<Strategy>) ); |
| |
| typedef typename Strategy::return_type type; |
| |
| static inline type apply(Ring const& ring, Strategy const& strategy) |
| { |
| assert_dimension<Ring, 2>(); |
| |
| // Ignore warning (because using static method sometimes) on strategy |
| boost::ignore_unused_variable_warning(strategy); |
| |
| // An open ring has at least three points, |
| // A closed ring has at least four points, |
| // if not, there is no (zero) area |
| if (boost::size(ring) |
| < core_detail::closure::minimum_ring_size<Closure>::value) |
| { |
| return type(); |
| } |
| |
| typedef typename reversible_view<Ring const, Direction>::type rview_type; |
| typedef typename closeable_view |
| < |
| rview_type const, Closure |
| >::type view_type; |
| typedef typename boost::range_iterator<view_type const>::type iterator_type; |
| |
| rview_type rview(ring); |
| view_type view(rview); |
| typename Strategy::state_type state; |
| iterator_type it = boost::begin(view); |
| iterator_type end = boost::end(view); |
| |
| for (iterator_type previous = it++; |
| it != end; |
| ++previous, ++it) |
| { |
| strategy.apply(*previous, *it, state); |
| } |
| |
| return strategy.result(state); |
| } |
| }; |
| |
| |
| }} // namespace detail::area |
| |
| |
| #endif // DOXYGEN_NO_DETAIL |
| |
| |
| #ifndef DOXYGEN_NO_DISPATCH |
| namespace dispatch |
| { |
| |
| template |
| < |
| typename Tag, |
| typename Geometry, |
| typename Strategy |
| > |
| struct area |
| : detail::calculate_null |
| < |
| typename Strategy::return_type, |
| Geometry, |
| Strategy |
| > {}; |
| |
| |
| template |
| < |
| typename Geometry, |
| typename Strategy |
| > |
| struct area<box_tag, Geometry, Strategy> |
| : detail::area::box_area<Geometry, Strategy> |
| {}; |
| |
| |
| template |
| < |
| typename Ring, |
| typename Strategy |
| > |
| struct area<ring_tag, Ring, Strategy> |
| : detail::area::ring_area |
| < |
| Ring, |
| order_as_direction<geometry::point_order<Ring>::value>::value, |
| geometry::closure<Ring>::value, |
| Strategy |
| > |
| {}; |
| |
| |
| template |
| < |
| typename Polygon, |
| typename Strategy |
| > |
| struct area<polygon_tag, Polygon, Strategy> |
| : detail::calculate_polygon_sum |
| < |
| typename Strategy::return_type, |
| Polygon, |
| Strategy, |
| detail::area::ring_area |
| < |
| typename ring_type<Polygon const>::type, |
| order_as_direction<geometry::point_order<Polygon>::value>::value, |
| geometry::closure<Polygon>::value, |
| Strategy |
| > |
| > |
| {}; |
| |
| |
| } // namespace dispatch |
| #endif // DOXYGEN_NO_DISPATCH |
| |
| |
| |
| /*! |
| \brief \brief_calc{area} |
| \ingroup area |
| \details \details_calc{area}. \details_default_strategy |
| |
| The area algorithm calculates the surface area of all geometries having a surface, namely |
| box, polygon, ring, multipolygon. The units are the square of the units used for the points |
| defining the surface. If subject geometry is defined in meters, then area is calculated |
| in square meters. |
| |
| The area calculation can be done in all three common coordinate systems, Cartesian, Spherical |
| and Geographic as well. |
| |
| \tparam Geometry \tparam_geometry |
| \param geometry \param_geometry |
| \return \return_calc{area} |
| |
| \qbk{[include reference/algorithms/area.qbk]} |
| \qbk{[heading Examples]} |
| \qbk{[area] [area_output]} |
| */ |
| template <typename Geometry> |
| inline typename default_area_result<Geometry>::type area(Geometry const& geometry) |
| { |
| concept::check<Geometry const>(); |
| |
| typedef typename point_type<Geometry>::type point_type; |
| typedef typename strategy::area::services::default_strategy |
| < |
| typename cs_tag<point_type>::type, |
| point_type |
| >::type strategy_type; |
| |
| return dispatch::area |
| < |
| typename tag<Geometry>::type, |
| Geometry, |
| strategy_type |
| >::apply(geometry, strategy_type()); |
| } |
| |
| /*! |
| \brief \brief_calc{area} \brief_strategy |
| \ingroup area |
| \details \details_calc{area} \brief_strategy. \details_strategy_reasons |
| \tparam Geometry \tparam_geometry |
| \tparam Strategy \tparam_strategy{Area} |
| \param geometry \param_geometry |
| \param strategy \param_strategy{area} |
| \return \return_calc{area} |
| |
| \qbk{distinguish,with strategy} |
| |
| \qbk{ |
| [include reference/algorithms/area.qbk] |
| |
| [heading Example] |
| [area_with_strategy] |
| [area_with_strategy_output] |
| |
| [heading Available Strategies] |
| \* [link geometry.reference.strategies.strategy_area_surveyor Surveyor (cartesian)] |
| \* [link geometry.reference.strategies.strategy_area_huiller Huiller (spherical)] |
| } |
| */ |
| template <typename Geometry, typename Strategy> |
| inline typename Strategy::return_type area( |
| Geometry const& geometry, Strategy const& strategy) |
| { |
| concept::check<Geometry const>(); |
| |
| return dispatch::area |
| < |
| typename tag<Geometry>::type, |
| Geometry, |
| Strategy |
| >::apply(geometry, strategy); |
| } |
| |
| |
| }} // namespace boost::geometry |
| |
| |
| #endif // BOOST_GEOMETRY_ALGORITHMS_AREA_HPP |