// // Copyright 2005-2007 Adobe Systems Incorporated // // Distributed under 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_GIL_POSITION_ITERATOR_HPP #define BOOST_GIL_POSITION_ITERATOR_HPP #include <boost/gil/locator.hpp> #include <boost/iterator/iterator_facade.hpp> #include <type_traits> namespace boost { namespace gil { /// \defgroup PixelIteratorModelVirtual position_iterator /// \ingroup PixelIteratorModel /// \brief An iterator that remembers its current X,Y position and invokes a function object with it upon dereferencing. /// Models PixelIteratorConcept, PixelBasedConcept, HasDynamicXStepTypeConcept. Used to create virtual image views. /// \brief An iterator that remembers its current X,Y position and invokes a function object with it upon dereferencing. /// Used to create virtual image views. /// Models: StepIteratorConcept, PixelIteratorConcept, PixelBasedConcept, HasDynamicXStepTypeConcept /// \ingroup PixelIteratorModelVirtual PixelBasedModel /// \tparam Deref A function object that given a point returns a pixel reference. Models PixelDereferenceAdaptorConcept /// \tparam Dim Dimension to advance along template <typename Deref, int Dim> struct position_iterator : public iterator_facade<position_iterator<Deref,Dim>, typename Deref::value_type, std::random_access_iterator_tag, typename Deref::reference, typename Deref::argument_type::template axis<Dim>::coord_t> { using parent_t = iterator_facade<position_iterator<Deref,Dim>, typename Deref::value_type, std::random_access_iterator_tag, typename Deref::reference, typename Deref::argument_type::template axis<Dim>::coord_t>; using difference_type = typename parent_t::difference_type; using reference = typename parent_t::reference; using point_t = typename Deref::argument_type; position_iterator() {} position_iterator(const point_t& p, const point_t& step, const Deref& d) : _p(p), _step(step), _d(d) {} position_iterator(const position_iterator& p) : _p(p._p), _step(p._step), _d(p._d) {} template <typename D> position_iterator(const position_iterator<D,Dim>& p) : _p(p._p), _step(p._step), _d(p._d) {} position_iterator& operator=(const position_iterator& p) { _p=p._p; _d=p._d; _step=p._step; return *this; } const point_t& pos() const { return _p; } const point_t& step() const { return _step; } const Deref& deref_fn() const { return _d; } void set_step(difference_type s) { _step[Dim]=s; } /// For some reason operator[] provided by iterator_adaptor returns a custom class that is convertible to reference /// We require our own reference because it is registered in iterator_traits reference operator[](difference_type d) const { point_t p=_p; p[Dim]+=d*_step[Dim]; return _d(p); } private: point_t _p, _step; Deref _d; template <typename DE, int DI> friend struct position_iterator; friend class boost::iterator_core_access; reference dereference() const { return _d(_p); } void increment() { _p[Dim]+=_step[Dim]; } void decrement() { _p[Dim]-=_step[Dim]; } void advance(difference_type d) { _p[Dim]+=d*_step[Dim]; } difference_type distance_to(const position_iterator& it) const { return (it._p[Dim]-_p[Dim])/_step[Dim]; } bool equal(const position_iterator& it) const { return _p==it._p; } }; template <typename Deref,int Dim> struct const_iterator_type<position_iterator<Deref,Dim> > { using type = position_iterator<typename Deref::const_t,Dim>; }; template <typename Deref, int Dim> struct iterator_is_mutable<position_iterator<Deref, Dim>> : std::integral_constant<bool, Deref::is_mutable> { }; ///////////////////////////// // PixelBasedConcept ///////////////////////////// template <typename Deref,int Dim> struct color_space_type<position_iterator<Deref,Dim> > : public color_space_type<typename Deref::value_type> {}; template <typename Deref,int Dim> struct channel_mapping_type<position_iterator<Deref,Dim> > : public channel_mapping_type<typename Deref::value_type> {}; template <typename Deref,int Dim> struct is_planar<position_iterator<Deref, Dim>> : std::false_type {}; template <typename Deref,int Dim> struct channel_type<position_iterator<Deref,Dim> > : public channel_type<typename Deref::value_type> {}; ///////////////////////////// // HasDynamicXStepTypeConcept ///////////////////////////// template <typename Deref,int Dim> struct dynamic_x_step_type<position_iterator<Deref,Dim> > { using type = position_iterator<Deref,Dim>; }; } } // namespace boost::gil #endif