/*

    Copyright 2005-2007 Adobe Systems Incorporated

   

    Use, modification and distribution are 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).



    See http://opensource.adobe.com/gil for most recent version including documentation.

*/



/*************************************************************************************************/



#ifndef GIL_POSITION_ITERATOR_HPP

#define GIL_POSITION_ITERATOR_HPP



////////////////////////////////////////////////////////////////////////////////////////

/// \file               

/// \brief Locator for virtual image views

/// \author Lubomir Bourdev and Hailin Jin \n

///         Adobe Systems Incorporated

/// \date   2005-2007 \n Last updated on February 12, 2007

///

////////////////////////////////////////////////////////////////////////////////////////



#include <boost/iterator/iterator_facade.hpp>

#include "locator.hpp"



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. Models PixelIteratorConcept. Used to create virtual image views.

///    Models: StepIteratorConcept, PixelIteratorConcept, PixelBasedConcept, HasDynamicXStepTypeConcept

/// \ingroup PixelIteratorModelVirtual PixelBasedModel

template <typename Deref, // A function object that given a point returns a pixel reference. Models PixelDereferenceAdaptorConcept

          int Dim>        // the dimension to advance along

struct position_iterator : public iterator_facade<position_iterator<Deref,Dim>,

                                                  typename Deref::value_type,

                                                  random_access_traversal_tag,

                                                  typename Deref::reference,

                                                  typename Deref::argument_type::template axis<Dim>::coord_t> {

    typedef iterator_facade<position_iterator<Deref,Dim>,

                            typename Deref::value_type,

                            random_access_traversal_tag,

                            typename Deref::reference,

                            typename Deref::argument_type::template axis<Dim>::coord_t> parent_t;

    typedef typename parent_t::difference_type difference_type;

    typedef typename parent_t::reference       reference;

    typedef typename Deref::argument_type      point_t;



    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> > {

    typedef position_iterator<typename Deref::const_t,Dim> type;

};



template <typename Deref,int Dim> 

struct iterator_is_mutable<position_iterator<Deref,Dim> > : public mpl::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> > : public mpl::false_ {};



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> > {

    typedef position_iterator<Deref,Dim> type;

};



} }  // namespace boost::gil



#endif

