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- // Boost.Geometry (aka GGL, Generic Geometry Library)
- // Copyright (c) 2007-2012 Barend Gehrels, 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_DETAIL_OVERLAY_GET_RING_HPP
- #define BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_GET_RING_HPP
- #include <boost/range.hpp>
- #include <boost/geometry/core/assert.hpp>
- #include <boost/geometry/core/exterior_ring.hpp>
- #include <boost/geometry/core/interior_rings.hpp>
- #include <boost/geometry/core/ring_type.hpp>
- #include <boost/geometry/core/tags.hpp>
- #include <boost/geometry/algorithms/detail/ring_identifier.hpp>
- #include <boost/geometry/algorithms/detail/overlay/segment_identifier.hpp>
- #include <boost/geometry/algorithms/num_points.hpp>
- #include <boost/geometry/geometries/concepts/check.hpp>
- #include <boost/geometry/util/range.hpp>
- namespace boost { namespace geometry
- {
- #ifndef DOXYGEN_NO_DETAIL
- namespace detail { namespace overlay
- {
- template<typename Tag>
- struct get_ring
- {};
- // A range of rings (multi-ring but that does not exist)
- // gets the "void" tag and is dispatched here.
- template<>
- struct get_ring<void>
- {
- template<typename Range>
- static inline typename boost::range_value<Range>::type const&
- apply(ring_identifier const& id, Range const& container)
- {
- return range::at(container, id.multi_index);
- }
- };
- template<>
- struct get_ring<ring_tag>
- {
- template<typename Ring>
- static inline Ring const& apply(ring_identifier const& , Ring const& ring)
- {
- return ring;
- }
- };
- template<>
- struct get_ring<box_tag>
- {
- template<typename Box>
- static inline Box const& apply(ring_identifier const& ,
- Box const& box)
- {
- return box;
- }
- };
- template<>
- struct get_ring<polygon_tag>
- {
- template<typename Polygon>
- static inline typename ring_return_type<Polygon const>::type const apply(
- ring_identifier const& id,
- Polygon const& polygon)
- {
- BOOST_GEOMETRY_ASSERT
- (
- id.ring_index >= -1
- && id.ring_index < int(boost::size(interior_rings(polygon)))
- );
- return id.ring_index < 0
- ? exterior_ring(polygon)
- : range::at(interior_rings(polygon), id.ring_index);
- }
- };
- template<>
- struct get_ring<multi_polygon_tag>
- {
- template<typename MultiPolygon>
- static inline typename ring_type<MultiPolygon>::type const& apply(
- ring_identifier const& id,
- MultiPolygon const& multi_polygon)
- {
- BOOST_GEOMETRY_ASSERT
- (
- id.multi_index >= 0
- && id.multi_index < int(boost::size(multi_polygon))
- );
- return get_ring<polygon_tag>::apply(id,
- range::at(multi_polygon, id.multi_index));
- }
- };
- template <typename Geometry>
- inline std::size_t segment_count_on_ring(Geometry const& geometry,
- segment_identifier const& seg_id)
- {
- typedef typename geometry::tag<Geometry>::type tag;
- ring_identifier const rid(0, seg_id.multi_index, seg_id.ring_index);
- // A closed polygon, a triangle of 4 points, including starting point,
- // contains 3 segments. So handle as if closed and subtract one.
- return geometry::num_points(detail::overlay::get_ring<tag>::apply(rid, geometry), true) - 1;
- }
- }} // namespace detail::overlay
- #endif // DOXYGEN_NO_DETAIL
- }} // namespace boost::geometry
- #endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_GET_RING_HPP
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