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287 lines
7.3 KiB
287 lines
7.3 KiB
// Boost.Geometry (aka GGL, Generic Geometry Library) |
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// Copyright (c) 2007-2011 Barend Gehrels, Amsterdam, the Netherlands. |
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// Copyright (c) 2008-2011 Bruno Lalande, Paris, France. |
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// Copyright (c) 2009-2011 Mateusz Loskot, London, UK. |
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// Parts of Boost.Geometry are redesigned from Geodan's Geographic Library |
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// (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands. |
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// Use, modification and distribution is subject to the Boost Software License, |
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// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
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// http://www.boost.org/LICENSE_1_0.txt) |
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#ifndef BOOST_GEOMETRY_ALGORITHMS_AREA_HPP |
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#define BOOST_GEOMETRY_ALGORITHMS_AREA_HPP |
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#include <boost/concept_check.hpp> |
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#include <boost/mpl/if.hpp> |
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#include <boost/range/functions.hpp> |
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#include <boost/range/metafunctions.hpp> |
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#include <boost/geometry/core/closure.hpp> |
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#include <boost/geometry/core/exterior_ring.hpp> |
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#include <boost/geometry/core/interior_rings.hpp> |
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#include <boost/geometry/core/point_order.hpp> |
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#include <boost/geometry/core/ring_type.hpp> |
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#include <boost/geometry/geometries/concepts/check.hpp> |
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#include <boost/geometry/algorithms/detail/calculate_null.hpp> |
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#include <boost/geometry/algorithms/detail/calculate_sum.hpp> |
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#include <boost/geometry/strategies/area.hpp> |
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#include <boost/geometry/strategies/default_area_result.hpp> |
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#include <boost/geometry/strategies/concepts/area_concept.hpp> |
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#include <boost/geometry/util/math.hpp> |
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#include <boost/geometry/util/order_as_direction.hpp> |
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#include <boost/geometry/views/closeable_view.hpp> |
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#include <boost/geometry/views/reversible_view.hpp> |
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namespace boost { namespace geometry |
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{ |
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#ifndef DOXYGEN_NO_DETAIL |
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namespace detail { namespace area |
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{ |
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template<typename Box, typename Strategy> |
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struct box_area |
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{ |
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typedef typename coordinate_type<Box>::type return_type; |
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static inline return_type apply(Box const& box, Strategy const&) |
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{ |
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// Currently only works for 2D Cartesian boxes |
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assert_dimension<Box, 2>(); |
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return_type const dx = get<max_corner, 0>(box) |
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- get<min_corner, 0>(box); |
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return_type const dy = get<max_corner, 1>(box) |
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- get<min_corner, 1>(box); |
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return dx * dy; |
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} |
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}; |
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template |
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< |
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typename Ring, |
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iterate_direction Direction, |
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closure_selector Closure, |
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typename Strategy |
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> |
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struct ring_area |
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{ |
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BOOST_CONCEPT_ASSERT( (geometry::concept::AreaStrategy<Strategy>) ); |
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typedef typename Strategy::return_type type; |
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static inline type apply(Ring const& ring, Strategy const& strategy) |
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{ |
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assert_dimension<Ring, 2>(); |
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// Ignore warning (because using static method sometimes) on strategy |
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boost::ignore_unused_variable_warning(strategy); |
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// An open ring has at least three points, |
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// A closed ring has at least four points, |
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// if not, there is no (zero) area |
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if (boost::size(ring) |
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< core_detail::closure::minimum_ring_size<Closure>::value) |
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{ |
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return type(); |
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} |
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typedef typename reversible_view<Ring const, Direction>::type rview_type; |
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typedef typename closeable_view |
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< |
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rview_type const, Closure |
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>::type view_type; |
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typedef typename boost::range_iterator<view_type const>::type iterator_type; |
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rview_type rview(ring); |
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view_type view(rview); |
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typename Strategy::state_type state; |
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iterator_type it = boost::begin(view); |
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iterator_type end = boost::end(view); |
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for (iterator_type previous = it++; |
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it != end; |
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++previous, ++it) |
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{ |
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strategy.apply(*previous, *it, state); |
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} |
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return strategy.result(state); |
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} |
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}; |
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}} // namespace detail::area |
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#endif // DOXYGEN_NO_DETAIL |
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#ifndef DOXYGEN_NO_DISPATCH |
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namespace dispatch |
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{ |
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template |
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< |
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typename Tag, |
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typename Geometry, |
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typename Strategy |
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> |
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struct area |
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: detail::calculate_null |
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< |
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typename Strategy::return_type, |
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Geometry, |
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Strategy |
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> {}; |
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template |
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< |
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typename Geometry, |
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typename Strategy |
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> |
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struct area<box_tag, Geometry, Strategy> |
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: detail::area::box_area<Geometry, Strategy> |
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{}; |
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template |
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< |
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typename Ring, |
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typename Strategy |
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> |
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struct area<ring_tag, Ring, Strategy> |
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: detail::area::ring_area |
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< |
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Ring, |
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order_as_direction<geometry::point_order<Ring>::value>::value, |
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geometry::closure<Ring>::value, |
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Strategy |
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> |
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{}; |
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template |
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< |
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typename Polygon, |
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typename Strategy |
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> |
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struct area<polygon_tag, Polygon, Strategy> |
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: detail::calculate_polygon_sum |
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< |
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typename Strategy::return_type, |
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Polygon, |
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Strategy, |
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detail::area::ring_area |
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< |
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typename ring_type<Polygon const>::type, |
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order_as_direction<geometry::point_order<Polygon>::value>::value, |
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geometry::closure<Polygon>::value, |
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Strategy |
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> |
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> |
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{}; |
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} // namespace dispatch |
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#endif // DOXYGEN_NO_DISPATCH |
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/*! |
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\brief \brief_calc{area} |
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\ingroup area |
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\details \details_calc{area}. \details_default_strategy |
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The area algorithm calculates the surface area of all geometries having a surface, namely |
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box, polygon, ring, multipolygon. The units are the square of the units used for the points |
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defining the surface. If subject geometry is defined in meters, then area is calculated |
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in square meters. |
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The area calculation can be done in all three common coordinate systems, Cartesian, Spherical |
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and Geographic as well. |
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\tparam Geometry \tparam_geometry |
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\param geometry \param_geometry |
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\return \return_calc{area} |
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\qbk{[include reference/algorithms/area.qbk]} |
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\qbk{[heading Examples]} |
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\qbk{[area] [area_output]} |
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*/ |
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template <typename Geometry> |
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inline typename default_area_result<Geometry>::type area(Geometry const& geometry) |
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{ |
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concept::check<Geometry const>(); |
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typedef typename point_type<Geometry>::type point_type; |
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typedef typename strategy::area::services::default_strategy |
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< |
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typename cs_tag<point_type>::type, |
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point_type |
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>::type strategy_type; |
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return dispatch::area |
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< |
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typename tag<Geometry>::type, |
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Geometry, |
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strategy_type |
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>::apply(geometry, strategy_type()); |
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} |
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/*! |
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\brief \brief_calc{area} \brief_strategy |
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\ingroup area |
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\details \details_calc{area} \brief_strategy. \details_strategy_reasons |
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\tparam Geometry \tparam_geometry |
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\tparam Strategy \tparam_strategy{Area} |
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\param geometry \param_geometry |
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\param strategy \param_strategy{area} |
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\return \return_calc{area} |
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\qbk{distinguish,with strategy} |
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\qbk{ |
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[include reference/algorithms/area.qbk] |
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[heading Example] |
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[area_with_strategy] |
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[area_with_strategy_output] |
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[heading Available Strategies] |
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\* [link geometry.reference.strategies.strategy_area_surveyor Surveyor (cartesian)] |
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\* [link geometry.reference.strategies.strategy_area_huiller Huiller (spherical)] |
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} |
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*/ |
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template <typename Geometry, typename Strategy> |
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inline typename Strategy::return_type area( |
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Geometry const& geometry, Strategy const& strategy) |
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{ |
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concept::check<Geometry const>(); |
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return dispatch::area |
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< |
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typename tag<Geometry>::type, |
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Geometry, |
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Strategy |
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>::apply(geometry, strategy); |
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} |
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}} // namespace boost::geometry |
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#endif // BOOST_GEOMETRY_ALGORITHMS_AREA_HPP
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