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180 lines
4.5 KiB
180 lines
4.5 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_CORE_CLOSURE_HPP |
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#define BOOST_GEOMETRY_CORE_CLOSURE_HPP |
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#include <boost/mpl/assert.hpp> |
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#include <boost/mpl/int.hpp> |
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#include <boost/range.hpp> |
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#include <boost/type_traits/remove_const.hpp> |
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#include <boost/geometry/core/ring_type.hpp> |
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#include <boost/geometry/core/tag.hpp> |
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#include <boost/geometry/core/tags.hpp> |
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namespace boost { namespace geometry |
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{ |
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/*! |
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\brief Enumerates options for defining if polygons are open or closed |
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\ingroup enum |
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\details The enumeration closure_selector describes options for if a polygon is |
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open or closed. In a closed polygon the very first point (per ring) should |
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be equal to the very last point. |
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The specific closing property of a polygon type is defined by the closure |
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metafunction. The closure metafunction defines a value, which is one of the |
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values enumerated in the closure_selector |
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\qbk{ |
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[heading See also] |
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[link geometry.reference.core.closure The closure metafunction] |
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} |
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*/ |
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enum closure_selector |
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{ |
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/// Rings are open: first point and last point are different, algorithms |
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/// close them explicitly on the fly |
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open = 0, |
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/// Rings are closed: first point and last point must be the same |
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closed = 1, |
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/// (Not yet implemented): algorithms first figure out if ring must be |
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/// closed on the fly |
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closure_undertermined = -1 |
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}; |
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namespace traits |
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{ |
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/*! |
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\brief Traits class indicating if points within a |
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ring or (multi)polygon are closed (last point == first point), |
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open or not known. |
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\ingroup traits |
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\par Geometries: |
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- ring |
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\tparam G geometry |
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*/ |
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template <typename G> |
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struct closure |
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{ |
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static const closure_selector value = closed; |
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}; |
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} // namespace traits |
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#ifndef DOXYGEN_NO_DETAIL |
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namespace core_detail { namespace closure |
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{ |
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struct closed |
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{ |
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static const closure_selector value = geometry::closed; |
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}; |
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/// Metafunction to define the minimum size of a ring: |
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/// 3 for open rings, 4 for closed rings |
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template <closure_selector Closure> |
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struct minimum_ring_size {}; |
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template <> |
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struct minimum_ring_size<geometry::closed> : boost::mpl::int_<4> {}; |
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template <> |
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struct minimum_ring_size<geometry::open> : boost::mpl::int_<3> {}; |
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}} // namespace detail::point_order |
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#endif // DOXYGEN_NO_DETAIL |
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#ifndef DOXYGEN_NO_DISPATCH |
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namespace core_dispatch |
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{ |
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template <typename Tag, typename Geometry> |
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struct closure |
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{ |
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BOOST_MPL_ASSERT_MSG |
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( |
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false, NOT_IMPLEMENTED_FOR_THIS_GEOMETRY_TYPE |
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, (types<Geometry>) |
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); |
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}; |
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template <typename Box> |
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struct closure<point_tag, Box> : public core_detail::closure::closed {}; |
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template <typename Box> |
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struct closure<box_tag, Box> : public core_detail::closure::closed {}; |
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template <typename Box> |
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struct closure<segment_tag, Box> : public core_detail::closure::closed {}; |
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template <typename LineString> |
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struct closure<linestring_tag, LineString> |
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: public core_detail::closure::closed {}; |
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template <typename Ring> |
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struct closure<ring_tag, Ring> |
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{ |
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static const closure_selector value |
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= geometry::traits::closure<Ring>::value; |
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}; |
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// Specialization for polygon: the closure is the closure of its rings |
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template <typename Polygon> |
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struct closure<polygon_tag, Polygon> |
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{ |
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static const closure_selector value = core_dispatch::closure |
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< |
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ring_tag, |
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typename ring_type<polygon_tag, Polygon>::type |
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>::value ; |
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}; |
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} // namespace core_dispatch |
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#endif // DOXYGEN_NO_DISPATCH |
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/*! |
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\brief \brief_meta{value, closure (clockwise\, counterclockwise), |
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\meta_geometry_type} |
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\tparam Geometry \tparam_geometry |
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\ingroup core |
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\qbk{[include reference/core/closure.qbk]} |
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*/ |
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template <typename Geometry> |
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struct closure |
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{ |
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static const closure_selector value = core_dispatch::closure |
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< |
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typename tag<Geometry>::type, |
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typename boost::remove_const<Geometry>::type |
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>::value; |
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}; |
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}} // namespace boost::geometry |
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#endif // BOOST_GEOMETRY_CORE_CLOSURE_HPP
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