/*

    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_PIXEL_ITERATOR_H

#define GIL_PIXEL_ITERATOR_H



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

/// \file               

/// \brief pixel iterator support

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

///         Adobe Systems Incorporated

/// \date   2005-2007 \n May 16, 2006

///

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



#include <cassert>

#include <iterator>

#include "gil_config.hpp"

#include "gil_concept.hpp"

#include "utilities.hpp"

#include "pixel.hpp"



namespace boost { namespace gil {



//forwarded declaration (as this file is included in step_iterator.hpp)

template <typename Iterator>

class memory_based_step_iterator;



template <typename Iterator> struct dynamic_x_step_type;



/// \brief metafunction predicate determining whether the given iterator is a plain one or an adaptor over another iterator.

/// Examples of adaptors are the step iterator and the dereference iterator adaptor.

template <typename It>

struct is_iterator_adaptor : public mpl::false_{};



/// \brief returns the base iterator for a given iterator adaptor. Provide an specialization when introducing new iterator adaptors

template <typename It>

struct iterator_adaptor_get_base;



/// \brief Changes the base iterator of an iterator adaptor. Provide an specialization when introducing new iterator adaptors

template <typename It, typename NewBaseIt>

struct iterator_adaptor_rebind;



/// \brief Returns the type of an iterator just like the input iterator, except operating over immutable values

template <typename It>

struct const_iterator_type;



// The default implementation when the iterator is a C pointer is to use the standard constness semantics

template <typename T> struct const_iterator_type<      T*> { typedef const T* type; };

template <typename T> struct const_iterator_type<const T*> { typedef const T* type; };



/// \brief Metafunction predicate returning whether the given iterator allows for changing its values

/// \ingroup GILIsMutable

template <typename It>

struct iterator_is_mutable{};



// The default implementation when the iterator is a C pointer is to use the standard constness semantics

template <typename T> struct iterator_is_mutable<      T*> : public mpl::true_{};

template <typename T> struct iterator_is_mutable<const T*> : public mpl::false_{};



/// \defgroup PixelIteratorModelInterleavedPtr C pointer to a pixel

/// \ingroup PixelIteratorModel

/// \brief Iterators over interleaved pixels.

/// A C pointer to a model of PixelValueConcept is used as an iterator over interleaved pixels. Models PixelIteratorConcept, HomogeneousPixelBasedConcept, HasDynamicXStepTypeConcept, MemoryBasedIteratorConcept







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

//  HasDynamicXStepTypeConcept

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



/// \ingroup PixelIteratorModelInterleavedPtr 

template <typename Pixel>

struct dynamic_x_step_type<Pixel*> {

    typedef memory_based_step_iterator<Pixel*> type;

};



/// \ingroup PixelIteratorModelInterleavedPtr 

template <typename Pixel>

struct dynamic_x_step_type<const Pixel*> {

    typedef memory_based_step_iterator<const Pixel*> type;

};





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

//  PixelBasedConcept

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



template <typename Pixel> struct color_space_type<      Pixel*> : public color_space_type<Pixel> {};

template <typename Pixel> struct color_space_type<const Pixel*> : public color_space_type<Pixel> {};



template <typename Pixel> struct channel_mapping_type<      Pixel*> : public channel_mapping_type<Pixel> {};

template <typename Pixel> struct channel_mapping_type<const Pixel*> : public channel_mapping_type<Pixel> {};



template <typename Pixel> struct is_planar<      Pixel*> : public is_planar<Pixel> {};

template <typename Pixel> struct is_planar<const Pixel*> : public is_planar<Pixel> {};



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

//  HomogeneousPixelBasedConcept

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



template <typename Pixel> struct channel_type<Pixel*> : public channel_type<Pixel> {};

template <typename Pixel> struct channel_type<const Pixel*> : public channel_type<Pixel> {};



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

///

/// Support for pixel iterator movement measured in memory units (bytes or bits) as opposed to pixel type. \n

/// Necessary to handle image row alignment and channel plane alignment.

///

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



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

//  MemoryBasedIteratorConcept

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



template <typename T>

struct byte_to_memunit : public mpl::int_<1> {};



template <typename P>

inline std::ptrdiff_t memunit_step(const P*) { return sizeof(P); }



template <typename P>

inline std::ptrdiff_t memunit_distance(const P* p1, const P* p2) { 

    return (gil_reinterpret_cast_c<const unsigned char*>(p2)-gil_reinterpret_cast_c<const unsigned char*>(p1)); 

}



template <typename P>

inline void memunit_advance(P* &p, std::ptrdiff_t diff) { 

    p=(P*)((unsigned char*)(p)+diff);

}



template <typename P>

inline P* memunit_advanced(const P* p, std::ptrdiff_t diff) {

    return (P*)((char*)(p)+diff);

}



//  memunit_advanced_ref

//  (shortcut to advancing a pointer by a given number of memunits and taking the reference in case the compiler is not smart enough)



template <typename P>

inline P& memunit_advanced_ref(P* p, std::ptrdiff_t diff) {

    return *memunit_advanced(p,diff);

}



} }  // namespace boost::gil



#endif

