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// Boost.Geometry (aka GGL, Generic Geometry Library)
// Copyright (c) 2014-2017, Oracle and/or its affiliates.
// Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
// Licensed under the Boost Software License version 1.0.
// http://www.boost.org/users/license.html
#ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_IS_VALID_RING_HPP
#define BOOST_GEOMETRY_ALGORITHMS_DETAIL_IS_VALID_RING_HPP
#include <deque>
#include <boost/core/ignore_unused.hpp>
#include <boost/geometry/core/closure.hpp>
#include <boost/geometry/core/cs.hpp>
#include <boost/geometry/core/point_order.hpp>
#include <boost/geometry/util/order_as_direction.hpp>
#include <boost/geometry/util/range.hpp>
#include <boost/geometry/algorithms/equals.hpp>
#include <boost/geometry/views/closeable_view.hpp>
#include <boost/geometry/algorithms/area.hpp>
#include <boost/geometry/algorithms/intersects.hpp>
#include <boost/geometry/algorithms/validity_failure_type.hpp>
#include <boost/geometry/algorithms/detail/num_distinct_consecutive_points.hpp>
#include <boost/geometry/algorithms/detail/is_valid/has_duplicates.hpp>
#include <boost/geometry/algorithms/detail/is_valid/has_invalid_coordinate.hpp>
#include <boost/geometry/algorithms/detail/is_valid/has_spikes.hpp>
#include <boost/geometry/algorithms/detail/is_valid/has_valid_self_turns.hpp>
#include <boost/geometry/strategies/area.hpp>
#ifdef BOOST_GEOMETRY_TEST_DEBUG
#include <boost/geometry/io/dsv/write.hpp>
#endif
namespace boost { namespace geometry
{
#ifndef DOXYGEN_NO_DETAIL
namespace detail { namespace is_valid
{
// struct to check whether a ring is topologically closed
template <typename Ring, closure_selector Closure /* open */>
struct is_topologically_closed
{
template <typename VisitPolicy>
static inline bool apply(Ring const&, VisitPolicy& visitor)
{
boost::ignore_unused(visitor);
return visitor.template apply<no_failure>();
}
};
template <typename Ring>
struct is_topologically_closed<Ring, closed>
{
template <typename VisitPolicy>
static inline bool apply(Ring const& ring, VisitPolicy& visitor)
{
boost::ignore_unused(visitor);
if (geometry::equals(range::front(ring), range::back(ring)))
{
return visitor.template apply<no_failure>();
}
else
{
return visitor.template apply<failure_not_closed>();
}
}
};
template <typename ResultType, bool IsInteriorRing /* false */>
struct ring_area_predicate
{
typedef std::greater<ResultType> type;
};
template <typename ResultType>
struct ring_area_predicate<ResultType, true>
{
typedef std::less<ResultType> type;
};
template <typename Ring, bool IsInteriorRing>
struct is_properly_oriented
{
template <typename VisitPolicy, typename Strategy>
static inline bool apply(Ring const& ring, VisitPolicy& visitor,
Strategy const& strategy)
{
boost::ignore_unused(visitor);
typedef typename point_type<Ring>::type point_type;
typedef detail::area::ring_area
<
order_as_direction<geometry::point_order<Ring>::value>::value,
geometry::closure<Ring>::value
> ring_area_type;
typedef typename default_area_result<Ring>::type area_result_type;
typename ring_area_predicate
<
area_result_type, IsInteriorRing
>::type predicate;
// Check area
area_result_type const zero = 0;
area_result_type const area
= ring_area_type::apply(ring,
strategy.template get_area_strategy<point_type>());
if (predicate(area, zero))
{
return visitor.template apply<no_failure>();
}
else
{
return visitor.template apply<failure_wrong_orientation>();
}
}
};
template
<
typename Ring,
bool CheckSelfIntersections = true,
bool IsInteriorRing = false
>
struct is_valid_ring
{
template <typename VisitPolicy, typename Strategy>
static inline bool apply(Ring const& ring, VisitPolicy& visitor,
Strategy const& strategy)
{
// return invalid if any of the following condition holds:
// (a) the ring's point coordinates are not invalid (e.g., NaN)
// (b) the ring's size is below the minimal one
// (c) the ring consists of at most two distinct points
// (d) the ring is not topologically closed
// (e) the ring has spikes
// (f) the ring has duplicate points (if AllowDuplicates is false)
// (g) the boundary of the ring has self-intersections
// (h) the order of the points is inconsistent with the defined order
//
// Note: no need to check if the area is zero. If this is the
// case, then the ring must have at least two spikes, which is
// checked by condition (d).
if (has_invalid_coordinate<Ring>::apply(ring, visitor))
{
return false;
}
closure_selector const closure = geometry::closure<Ring>::value;
typedef typename closeable_view<Ring const, closure>::type view_type;
if (boost::size(ring)
< core_detail::closure::minimum_ring_size<closure>::value)
{
return visitor.template apply<failure_few_points>();
}
view_type const view(ring);
if (detail::num_distinct_consecutive_points
<
view_type, 4u, true,
not_equal_to<typename point_type<Ring>::type>
>::apply(view)
< 4u)
{
return
visitor.template apply<failure_wrong_topological_dimension>();
}
return
is_topologically_closed<Ring, closure>::apply(ring, visitor)
&& ! has_duplicates<Ring, closure>::apply(ring, visitor)
&& ! has_spikes<Ring, closure>::apply(ring, visitor)
&& (! CheckSelfIntersections
|| has_valid_self_turns<Ring>::apply(ring, visitor, strategy))
&& is_properly_oriented<Ring, IsInteriorRing>::apply(ring, visitor, strategy);
}
};
}} // namespace detail::is_valid
#endif // DOXYGEN_NO_DETAIL
#ifndef DOXYGEN_NO_DISPATCH
namespace dispatch
{
// A Ring is a Polygon with exterior boundary only.
// The Ring's boundary must be a LinearRing (see OGC 06-103-r4,
// 6.1.7.1, for the definition of LinearRing)
//
// Reference (for polygon validity): OGC 06-103r4 (6.1.11.1)
template <typename Ring, bool AllowEmptyMultiGeometries>
struct is_valid
<
Ring, ring_tag, AllowEmptyMultiGeometries
> : detail::is_valid::is_valid_ring<Ring>
{};
} // namespace dispatch
#endif // DOXYGEN_NO_DISPATCH
}} // namespace boost::geometry
#endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_IS_VALID_RING_HPP
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