179 lines
4.2 KiB
C++
179 lines
4.2 KiB
C++
// 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_MULTI_ALGORITHMS_CENTROID_HPP
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#define BOOST_GEOMETRY_MULTI_ALGORITHMS_CENTROID_HPP
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#include <boost/range.hpp>
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#include <boost/geometry/algorithms/centroid.hpp>
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#include <boost/geometry/algorithms/num_points.hpp>
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#include <boost/geometry/multi/core/point_type.hpp>
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#include <boost/geometry/multi/algorithms/detail/multi_sum.hpp>
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#include <boost/geometry/multi/algorithms/num_points.hpp>
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namespace boost { namespace geometry
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{
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#ifndef DOXYGEN_NO_DETAIL
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namespace detail { namespace centroid
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{
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/*!
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\brief Building block of a multi-point, to be used as Policy in the
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more generec centroid_multi
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*/
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template
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<
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typename Point,
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typename Strategy
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>
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struct centroid_multi_point_state
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{
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static inline void apply(Point const& point,
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Strategy const& strategy, typename Strategy::state_type& state)
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{
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strategy.apply(point, state);
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}
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};
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/*!
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\brief Generic implementation which calls a policy to calculate the
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centroid of the total of its single-geometries
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\details The Policy is, in general, the single-version, with state. So
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detail::centroid::centroid_polygon_state is used as a policy for this
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detail::centroid::centroid_multi
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*/
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template
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<
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typename Multi,
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typename Point,
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typename Strategy,
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typename Policy
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>
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struct centroid_multi
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{
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static inline void apply(Multi const& multi, Point& centroid,
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Strategy const& strategy)
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{
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// If there is nothing in any of the ranges, it is not possible
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// to calculate the centroid
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if (geometry::num_points(multi) == 0)
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{
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throw centroid_exception();
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}
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typename Strategy::state_type state;
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for (typename boost::range_iterator<Multi const>::type
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it = boost::begin(multi);
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it != boost::end(multi);
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++it)
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{
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Policy::apply(*it, strategy, state);
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}
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Strategy::result(state, centroid);
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}
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};
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}} // namespace detail::centroid
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#endif // DOXYGEN_NO_DETAIL
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#ifndef DOXYGEN_NO_DISPATCH
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namespace dispatch
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{
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template
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<
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typename MultiLinestring,
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typename Point,
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typename Strategy
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>
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struct centroid<multi_linestring_tag, MultiLinestring, Point, Strategy>
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: detail::centroid::centroid_multi
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<
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MultiLinestring,
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Point,
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Strategy,
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detail::centroid::centroid_range_state
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<
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typename boost::range_value<MultiLinestring>::type,
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closed,
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Strategy
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>
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>
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{};
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template
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<
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typename MultiPolygon,
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typename Point,
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typename Strategy
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>
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struct centroid<multi_polygon_tag, MultiPolygon, Point, Strategy>
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: detail::centroid::centroid_multi
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<
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MultiPolygon,
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Point,
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Strategy,
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detail::centroid::centroid_polygon_state
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<
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typename boost::range_value<MultiPolygon>::type,
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Strategy
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>
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>
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{};
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template
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<
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typename MultiPoint,
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typename Point,
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typename Strategy
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>
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struct centroid<multi_point_tag, MultiPoint, Point, Strategy>
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: detail::centroid::centroid_multi
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<
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MultiPoint,
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Point,
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Strategy,
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detail::centroid::centroid_multi_point_state
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<
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typename boost::range_value<MultiPoint>::type,
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Strategy
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>
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>
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{};
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} // namespace dispatch
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#endif
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}} // namespace boost::geometry
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#endif // BOOST_GEOMETRY_MULTI_ALGORITHMS_CENTROID_HPP
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