Chris@102: // Boost.Geometry (aka GGL, Generic Geometry Library)
Chris@102: 
Chris@102: // Copyright (c) 2012-2014 Barend Gehrels, Amsterdam, the Netherlands.
Chris@102: 
Chris@102: // Use, modification and distribution is subject to the Boost Software License,
Chris@102: // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
Chris@102: // http://www.boost.org/LICENSE_1_0.txt)
Chris@102: 
Chris@102: #ifndef BOOST_GEOMETRY_STRATEGIES_AGNOSTIC_BUFFER_DISTANCE_SYMMETRIC_HPP
Chris@102: #define BOOST_GEOMETRY_STRATEGIES_AGNOSTIC_BUFFER_DISTANCE_SYMMETRIC_HPP
Chris@102: 
Chris@102: 
Chris@102: #include <boost/core/ignore_unused.hpp>
Chris@102: 
Chris@102: #include <boost/geometry/strategies/buffer.hpp>
Chris@102: #include <boost/geometry/util/math.hpp>
Chris@102: 
Chris@102: 
Chris@102: namespace boost { namespace geometry
Chris@102: {
Chris@102: 
Chris@102: namespace strategy { namespace buffer
Chris@102: {
Chris@102: 
Chris@102: 
Chris@102: /*!
Chris@102: \brief Let the buffer algorithm create buffers with same distances
Chris@102: \ingroup strategies
Chris@102: \tparam NumericType \tparam_numeric
Chris@102: \details This strategy can be used as DistanceStrategy for the buffer algorithm.
Chris@102:     It can be applied for all geometries. It uses one distance for left and
Chris@102:     for right.
Chris@102:     If the distance is negative and used with a (multi)polygon or ring, the
Chris@102:     geometry will shrink (deflate) instead of expand (inflate).
Chris@102: 
Chris@102: \qbk{
Chris@102: [heading Example]
Chris@102: [buffer_distance_symmetric]
Chris@102: [heading Output]
Chris@102: [$img/strategies/buffer_distance_symmetric.png]
Chris@102: [heading See also]
Chris@102: \* [link geometry.reference.algorithms.buffer.buffer_7_with_strategies buffer (with strategies)]
Chris@102: \* [link geometry.reference.strategies.strategy_buffer_distance_asymmetric distance_asymmetric]
Chris@102: }
Chris@102:  */
Chris@102: template<typename NumericType>
Chris@102: class distance_symmetric
Chris@102: {
Chris@102: public :
Chris@102:     //! \brief Constructs the strategy, a distance must be specified
Chris@102:     //! \param distance The distance (or radius) of the buffer
Chris@102:     explicit inline distance_symmetric(NumericType const& distance)
Chris@102:         : m_distance(distance)
Chris@102:     {}
Chris@102: 
Chris@102: #ifndef DOXYGEN_SHOULD_SKIP_THIS
Chris@102:     //! Returns the distance-value
Chris@102:     template <typename Point>
Chris@102:     inline NumericType apply(Point const& , Point const& ,
Chris@102:                 buffer_side_selector )  const
Chris@102:     {
Chris@102:         return negative() ? geometry::math::abs(m_distance) : m_distance;
Chris@102:     }
Chris@102: 
Chris@102:     //! Used internally, returns -1 for deflate, 1 for inflate
Chris@102:     inline int factor() const
Chris@102:     {
Chris@102:         return negative() ? -1 : 1;
Chris@102:     }
Chris@102: 
Chris@102:     //! Returns true if distance is negative
Chris@102:     inline bool negative() const
Chris@102:     {
Chris@102:         return m_distance < 0;
Chris@102:     }
Chris@102: 
Chris@102:     //! Returns the max distance distance up to the buffer will reach
Chris@102:     template <typename JoinStrategy, typename EndStrategy>
Chris@102:     inline NumericType max_distance(JoinStrategy const& join_strategy,
Chris@102:             EndStrategy const& end_strategy) const
Chris@102:     {
Chris@102:         boost::ignore_unused(join_strategy, end_strategy);
Chris@102: 
Chris@102:         NumericType const dist = geometry::math::abs(m_distance);
Chris@102:         return (std::max)(join_strategy.max_distance(dist),
Chris@102:                           end_strategy.max_distance(dist));
Chris@102:     }
Chris@102: 
Chris@102: 
Chris@102:     //! Returns the distance at which the input is simplified before the buffer process
Chris@102:     inline NumericType simplify_distance() const
Chris@102:     {
Chris@102:         return geometry::math::abs(m_distance) / 1000.0;
Chris@102:     }
Chris@102: #endif // DOXYGEN_SHOULD_SKIP_THIS
Chris@102: 
Chris@102: private :
Chris@102:     NumericType m_distance;
Chris@102: };
Chris@102: 
Chris@102: 
Chris@102: }} // namespace strategy::buffer
Chris@102: 
Chris@102: 
Chris@102: }} // namespace boost::geometry
Chris@102: 
Chris@102: #endif // BOOST_GEOMETRY_STRATEGIES_AGNOSTIC_BUFFER_DISTANCE_SYMMETRIC_HPP