181 lines
4.5 KiB
C++
181 lines
4.5 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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// 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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