boost/geometry/algorithms/correct.hpp

// Boost.Geometry (aka GGL, Generic Geometry Library)

// Copyright (c) 2007-2011 Barend Gehrels, Amsterdam, the Netherlands.
// Copyright (c) 2008-2011 Bruno Lalande, Paris, France.
// Copyright (c) 2009-2011 Mateusz Loskot, London, UK.

// Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
// (geolib/GGL), copyright (c) 1995-2010 Geodan, 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_CORRECT_HPP
#define BOOST_GEOMETRY_ALGORITHMS_CORRECT_HPP


#include <algorithm>
#include <cstddef>
#include <functional>

#include <boost/mpl/assert.hpp>
#include <boost/range.hpp>
#include <boost/typeof/typeof.hpp>

#include <boost/geometry/core/closure.hpp>
#include <boost/geometry/core/cs.hpp>
#include <boost/geometry/core/mutable_range.hpp>
#include <boost/geometry/core/ring_type.hpp>
#include <boost/geometry/core/exterior_ring.hpp>
#include <boost/geometry/core/interior_rings.hpp>

#include <boost/geometry/geometries/concepts/check.hpp>

#include <boost/geometry/algorithms/area.hpp>
#include <boost/geometry/algorithms/disjoint.hpp>
#include <boost/geometry/util/order_as_direction.hpp>


namespace boost { namespace geometry
{

#ifndef DOXYGEN_NO_DETAIL
namespace detail { namespace correct
{

template <typename Geometry>
struct correct_nop
{
    static inline void apply(Geometry& )
    {}
};


template <typename Box, std::size_t Dimension, std::size_t DimensionCount>
struct correct_box_loop
{
    typedef typename coordinate_type<Box>::type coordinate_type;

    static inline void apply(Box& box)
    {
        if (get<min_corner, Dimension>(box) > get<max_corner, Dimension>(box))
        {
            // Swap the coordinates
            coordinate_type max_value = get<min_corner, Dimension>(box);
            coordinate_type min_value = get<max_corner, Dimension>(box);
            set<min_corner, Dimension>(box, min_value);
            set<max_corner, Dimension>(box, max_value);
        }

        correct_box_loop
            <
                Box, Dimension + 1, DimensionCount
            >::apply(box);
    }
};



template <typename Box, std::size_t DimensionCount>
struct correct_box_loop<Box, DimensionCount, DimensionCount>
{
    static inline void apply(Box& box)
    {}

};


// Correct a box: make min/max correct
template <typename Box>
struct correct_box
{

    static inline void apply(Box& box)
    {
        // Currently only for Cartesian coordinates
        // (or spherical without crossing dateline)
        // Future version: adapt using strategies
        correct_box_loop
            <
                Box, 0, dimension<Box>::type::value
            >::apply(box);
    }
};


// Close a ring, if not closed
template <typename Ring, typename Predicate>
struct correct_ring
{
    typedef typename point_type<Ring>::type point_type;
    typedef typename coordinate_type<Ring>::type coordinate_type;

    typedef typename strategy::area::services::default_strategy
        <
            typename cs_tag<point_type>::type,
            point_type
        >::type strategy_type;

    typedef detail::area::ring_area
            <
                Ring,
                order_as_direction<geometry::point_order<Ring>::value>::value,
                geometry::closure<Ring>::value,
                strategy_type
            > ring_area_type;


    static inline void apply(Ring& r)
    {
        // Check close-ness
        if (boost::size(r) > 2)
        {
            // check if closed, if not, close it
            bool const disjoint = geometry::disjoint(*boost::begin(r), *(boost::end(r) - 1));
            closure_selector const s = geometry::closure<Ring>::value;

            if (disjoint && (s == closed))
            {
                geometry::append(r, *boost::begin(r));
            }
            if (! disjoint && geometry::closure<Ring>::value != closed)
            {
                // Open it by removing last point
                geometry::traits::resize<Ring>::apply(r, boost::size(r) - 1);
            }
        }
        // Check area
        Predicate predicate;
        coordinate_type const zero = 0;
        if (predicate(ring_area_type::apply(r, strategy_type()), zero))
        {
            std::reverse(boost::begin(r), boost::end(r));
        }
    }
};

// Correct a polygon: normalizes all rings, sets outer ring clockwise, sets all
// inner rings counter clockwise (or vice versa depending on orientation)
template <typename Polygon>
struct correct_polygon
{
    typedef typename ring_type<Polygon>::type ring_type;
    typedef typename coordinate_type<Polygon>::type coordinate_type;

    static inline void apply(Polygon& poly)
    {
        correct_ring
            <
                ring_type,
                std::less<coordinate_type>
            >::apply(exterior_ring(poly));

        typename interior_return_type<Polygon>::type rings
                    = interior_rings(poly);
        for (BOOST_AUTO_TPL(it, boost::begin(rings)); it != boost::end(rings); ++it)
        {
            correct_ring
                <
                    ring_type,
                    std::greater<coordinate_type>
                >::apply(*it);
        }
    }
};


}} // namespace detail::correct
#endif // DOXYGEN_NO_DETAIL


#ifndef DOXYGEN_NO_DISPATCH
namespace dispatch
{

template <typename Tag, typename Geometry>
struct correct
{
    BOOST_MPL_ASSERT_MSG
        (
            false, NOT_OR_NOT_YET_IMPLEMENTED_FOR_THIS_GEOMETRY_TYPE
            , (types<Geometry>)
        );
};

template <typename Point>
struct correct<point_tag, Point>
    : detail::correct::correct_nop<Point>
{};

template <typename LineString>
struct correct<linestring_tag, LineString>
    : detail::correct::correct_nop<LineString>
{};

template <typename Segment>
struct correct<segment_tag, Segment>
    : detail::correct::correct_nop<Segment>
{};


template <typename Box>
struct correct<box_tag, Box>
    : detail::correct::correct_box<Box>
{};

template <typename Ring>
struct correct<ring_tag, Ring>
    : detail::correct::correct_ring
        <
            Ring,
            std::less<typename coordinate_type<Ring>::type>
        >
{};

template <typename Polygon>
struct correct<polygon_tag, Polygon>
    : detail::correct::correct_polygon<Polygon>
{};


} // namespace dispatch
#endif // DOXYGEN_NO_DISPATCH


/*!
\brief Corrects a geometry
\details Corrects a geometry: all rings which are wrongly oriented with respect
    to their expected orientation are reversed. To all rings which do not have a
    closing point and are typed as they should have one, the first point is
    appended. Also boxes can be corrected.
\ingroup correct
\tparam Geometry \tparam_geometry
\param geometry \param_geometry which will be corrected if necessary

\qbk{[include reference/algorithms/correct.qbk]}
*/
template <typename Geometry>
inline void correct(Geometry& geometry)
{
    concept::check<Geometry const>();

    dispatch::correct<typename tag<Geometry>::type, Geometry>::apply(geometry);
}


}} // namespace boost::geometry


#endif // BOOST_GEOMETRY_ALGORITHMS_CORRECT_HPP