373 lines
10 KiB
C++
373 lines
10 KiB
C++
// Boost.Geometry (aka GGL, Generic Geometry Library)
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// Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.
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// Copyright (c) 2008-2012 Bruno Lalande, Paris, France.
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// Copyright (c) 2009-2012 Mateusz Loskot, London, UK.
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// Copyright (c) 2017-2022 Adam Wulkiewicz, Lodz, Poland.
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// This file was modified by Oracle on 2017-2021.
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// Modifications copyright (c) 2017-2021 Oracle and/or its affiliates.
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// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
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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/core/ignore_unused.hpp>
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#include <boost/range/begin.hpp>
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#include <boost/range/end.hpp>
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#include <boost/range/size.hpp>
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#include <boost/range/value_type.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/point_type.hpp>
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#include <boost/geometry/core/ring_type.hpp>
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#include <boost/geometry/core/tags.hpp>
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#include <boost/geometry/core/visit.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/algorithms/detail/throw_on_empty_input.hpp>
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#include <boost/geometry/algorithms/detail/multi_sum.hpp>
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#include <boost/geometry/algorithms/detail/visit.hpp>
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#include <boost/geometry/algorithms/area_result.hpp>
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#include <boost/geometry/algorithms/default_area_result.hpp>
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#include <boost/geometry/geometries/adapted/boost_variant.hpp> // For backward compatibility
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#include <boost/geometry/geometries/concepts/check.hpp>
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#include <boost/geometry/strategies/area/services.hpp>
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#include <boost/geometry/strategies/area/cartesian.hpp>
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#include <boost/geometry/strategies/area/geographic.hpp>
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#include <boost/geometry/strategies/area/spherical.hpp>
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#include <boost/geometry/strategies/concepts/area_concept.hpp>
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#include <boost/geometry/strategies/default_strategy.hpp>
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#include <boost/geometry/util/math.hpp>
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#include <boost/geometry/views/detail/closed_clockwise_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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struct box_area
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{
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template <typename Box, typename Strategies>
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static inline auto
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apply(Box const& box, Strategies const& strategies)
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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 strategies.area(box).apply(box);
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}
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};
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struct ring_area
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{
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template <typename Ring, typename Strategies>
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static inline typename area_result<Ring, Strategies>::type
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apply(Ring const& ring, Strategies const& strategies)
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{
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using strategy_type = decltype(strategies.area(ring));
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BOOST_CONCEPT_ASSERT( (geometry::concepts::AreaStrategy<Ring, strategy_type>) );
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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(strategies);
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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) < detail::minimum_ring_size<Ring>::value)
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{
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return typename area_result<Ring, Strategies>::type();
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}
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detail::closed_clockwise_view<Ring const> const view(ring);
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auto it = boost::begin(view);
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auto const end = boost::end(view);
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strategy_type const strategy = strategies.area(ring);
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typename strategy_type::template state<Ring> state;
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for (auto previous = it++; it != end; ++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 Geometry,
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typename Tag = typename tag<Geometry>::type
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>
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struct area : detail::calculate_null
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{
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template <typename Strategy>
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static inline typename area_result<Geometry, Strategy>::type
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apply(Geometry const& geometry, Strategy const& strategy)
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{
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return calculate_null::apply
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<
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typename area_result<Geometry, Strategy>::type
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>(geometry, strategy);
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}
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};
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template <typename Geometry>
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struct area<Geometry, box_tag> : detail::area::box_area
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{};
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template <typename Ring>
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struct area<Ring, ring_tag>
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: detail::area::ring_area
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{};
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template <typename Polygon>
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struct area<Polygon, polygon_tag> : detail::calculate_polygon_sum
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{
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template <typename Strategy>
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static inline typename area_result<Polygon, Strategy>::type
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apply(Polygon const& polygon, Strategy const& strategy)
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{
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return calculate_polygon_sum::apply
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<
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typename area_result<Polygon, Strategy>::type,
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detail::area::ring_area
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>(polygon, strategy);
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}
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};
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template <typename MultiGeometry>
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struct area<MultiGeometry, multi_polygon_tag> : detail::multi_sum
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{
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template <typename Strategy>
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static inline typename area_result<MultiGeometry, Strategy>::type
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apply(MultiGeometry const& multi, Strategy const& strategy)
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{
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return multi_sum::apply
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<
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typename area_result<MultiGeometry, Strategy>::type,
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area<typename boost::range_value<MultiGeometry>::type>
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>(multi, strategy);
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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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namespace resolve_strategy
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{
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template
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<
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typename Strategy,
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bool IsUmbrella = strategies::detail::is_umbrella_strategy<Strategy>::value
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>
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struct area
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{
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template <typename Geometry>
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static inline typename area_result<Geometry, Strategy>::type
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apply(Geometry const& geometry, Strategy const& strategy)
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{
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return dispatch::area<Geometry>::apply(geometry, strategy);
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}
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};
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template <typename Strategy>
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struct area<Strategy, false>
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{
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template <typename Geometry>
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static auto apply(Geometry const& geometry, Strategy const& strategy)
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{
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using strategies::area::services::strategy_converter;
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return dispatch::area
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<
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Geometry
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>::apply(geometry, strategy_converter<Strategy>::get(strategy));
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}
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};
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template <>
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struct area<default_strategy, false>
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{
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template <typename Geometry>
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static inline typename area_result<Geometry>::type
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apply(Geometry const& geometry, default_strategy)
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{
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typedef typename strategies::area::services::default_strategy
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<
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Geometry
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>::type strategy_type;
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return dispatch::area<Geometry>::apply(geometry, strategy_type());
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}
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};
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} // namespace resolve_strategy
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namespace resolve_dynamic
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{
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template <typename Geometry, typename Tag = typename geometry::tag<Geometry>::type>
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struct area
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{
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template <typename Strategy>
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static inline typename area_result<Geometry, Strategy>::type
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apply(Geometry const& geometry, Strategy const& strategy)
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{
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return resolve_strategy::area<Strategy>::apply(geometry, strategy);
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}
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};
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template <typename Geometry>
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struct area<Geometry, dynamic_geometry_tag>
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{
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template <typename Strategy>
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static inline typename area_result<Geometry, Strategy>::type
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apply(Geometry const& geometry, Strategy const& strategy)
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{
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typename area_result<Geometry, Strategy>::type result = 0;
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traits::visit<Geometry>::apply([&](auto const& g)
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{
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result = area<util::remove_cref_t<decltype(g)>>::apply(g, strategy);
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}, geometry);
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return result;
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}
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};
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template <typename Geometry>
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struct area<Geometry, geometry_collection_tag>
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{
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template <typename Strategy>
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static inline typename area_result<Geometry, Strategy>::type
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apply(Geometry const& geometry, Strategy const& strategy)
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{
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typename area_result<Geometry, Strategy>::type result = 0;
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detail::visit_breadth_first([&](auto const& g)
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{
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result += area<util::remove_cref_t<decltype(g)>>::apply(g, strategy);
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return true;
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}, geometry);
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return result;
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}
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};
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} // namespace resolve_dynamic
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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 area_result<Geometry>::type
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area(Geometry const& geometry)
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{
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concepts::check<Geometry const>();
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// detail::throw_on_empty_input(geometry);
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return resolve_dynamic::area<Geometry>::apply(geometry, default_strategy());
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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 Available Strategies]
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\* [link geometry.reference.strategies.strategy_area_cartesian Cartesian]
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\* [link geometry.reference.strategies.strategy_area_spherical Spherical]
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\* [link geometry.reference.strategies.strategy_area_geographic Geographic]
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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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}
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*/
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template <typename Geometry, typename Strategy>
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inline typename area_result<Geometry, Strategy>::type
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area(Geometry const& geometry, Strategy const& strategy)
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{
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concepts::check<Geometry const>();
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// detail::throw_on_empty_input(geometry);
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return resolve_dynamic::area<Geometry>::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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