//
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// Copyright 2005-2007 Adobe Systems Incorporated
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//
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// Distributed under the Boost Software License, Version 1.0
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// 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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//
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#ifndef BOOST_GIL_POSITION_ITERATOR_HPP
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#define BOOST_GIL_POSITION_ITERATOR_HPP
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#include <boost/gil/locator.hpp>
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#include <boost/iterator/iterator_facade.hpp>
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#include <type_traits>
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namespace boost { namespace gil {
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/// \defgroup PixelIteratorModelVirtual position_iterator
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/// \ingroup PixelIteratorModel
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/// \brief An iterator that remembers its current X,Y position and invokes a function object with it upon dereferencing.
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/// Models PixelIteratorConcept, PixelBasedConcept, HasDynamicXStepTypeConcept. Used to create virtual image views.
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/// \brief An iterator that remembers its current X,Y position and invokes a function object with it upon dereferencing.
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/// Used to create virtual image views.
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/// Models: StepIteratorConcept, PixelIteratorConcept, PixelBasedConcept, HasDynamicXStepTypeConcept
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/// \ingroup PixelIteratorModelVirtual PixelBasedModel
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/// \tparam Deref A function object that given a point returns a pixel reference. Models PixelDereferenceAdaptorConcept
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/// \tparam Dim Dimension to advance along
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template <typename Deref, int Dim>
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struct position_iterator : public iterator_facade<position_iterator<Deref,Dim>,
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typename Deref::value_type,
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std::random_access_iterator_tag,
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typename Deref::reference,
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typename Deref::argument_type::template axis<Dim>::coord_t> {
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using parent_t = iterator_facade<position_iterator<Deref,Dim>,
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typename Deref::value_type,
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std::random_access_iterator_tag,
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typename Deref::reference,
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typename Deref::argument_type::template axis<Dim>::coord_t>;
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using difference_type = typename parent_t::difference_type;
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using reference = typename parent_t::reference;
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using point_t = typename Deref::argument_type;
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position_iterator() {}
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position_iterator(const point_t& p, const point_t& step, const Deref& d) : _p(p), _step(step), _d(d) {}
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position_iterator(const position_iterator& p) : _p(p._p), _step(p._step), _d(p._d) {}
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template <typename D> position_iterator(const position_iterator<D,Dim>& p) : _p(p._p), _step(p._step), _d(p._d) {}
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position_iterator& operator=(const position_iterator& p) { _p=p._p; _d=p._d; _step=p._step; return *this; }
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const point_t& pos() const { return _p; }
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const point_t& step() const { return _step; }
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const Deref& deref_fn() const { return _d; }
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void set_step(difference_type s) { _step[Dim]=s; }
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/// For some reason operator[] provided by iterator_adaptor returns a custom class that is convertible to reference
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/// We require our own reference because it is registered in iterator_traits
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reference operator[](difference_type d) const { point_t p=_p; p[Dim]+=d*_step[Dim]; return _d(p); }
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private:
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point_t _p, _step;
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Deref _d;
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template <typename DE, int DI> friend struct position_iterator;
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friend class boost::iterator_core_access;
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reference dereference() const { return _d(_p); }
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void increment() { _p[Dim]+=_step[Dim]; }
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void decrement() { _p[Dim]-=_step[Dim]; }
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void advance(difference_type d) { _p[Dim]+=d*_step[Dim]; }
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difference_type distance_to(const position_iterator& it) const { return (it._p[Dim]-_p[Dim])/_step[Dim]; }
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bool equal(const position_iterator& it) const { return _p==it._p; }
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};
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template <typename Deref,int Dim>
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struct const_iterator_type<position_iterator<Deref,Dim> > {
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using type = position_iterator<typename Deref::const_t,Dim>;
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};
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template <typename Deref, int Dim>
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struct iterator_is_mutable<position_iterator<Deref, Dim>>
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: std::integral_constant<bool, Deref::is_mutable>
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{
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};
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/////////////////////////////
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// PixelBasedConcept
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/////////////////////////////
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template <typename Deref,int Dim>
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struct color_space_type<position_iterator<Deref,Dim> > : public color_space_type<typename Deref::value_type> {};
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template <typename Deref,int Dim>
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struct channel_mapping_type<position_iterator<Deref,Dim> > : public channel_mapping_type<typename Deref::value_type> {};
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template <typename Deref,int Dim>
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struct is_planar<position_iterator<Deref, Dim>> : std::false_type {};
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template <typename Deref,int Dim>
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struct channel_type<position_iterator<Deref,Dim> > : public channel_type<typename Deref::value_type> {};
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/////////////////////////////
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// HasDynamicXStepTypeConcept
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/////////////////////////////
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template <typename Deref,int Dim>
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struct dynamic_x_step_type<position_iterator<Deref,Dim> > {
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using type = position_iterator<Deref,Dim>;
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};
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} } // namespace boost::gil
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#endif
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