packed_pixel.hpp

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/*
    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_PACKED_PIXEL_H
#define GIL_PACKED_PIXEL_H

////////////////////////////////////////////////////////////////////////////////////////
/// \file
/// \brief A model of a heterogeneous pixel whose channels are bit ranges. For example 16-bit RGB in '565' format
/// \author Lubomir Bourdev and Hailin Jin \n
///         Adobe Systems Incorporated
/// \date   2005-2007 \n Last updated on September 28, 2006
///
////////////////////////////////////////////////////////////////////////////////////////

#include <functional>
#include <boost/utility/enable_if.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/mpl/front.hpp>
#include "gil_config.hpp"
#include "pixel.hpp"

namespace boost {
namespace gil {

/// \defgroup ColorBaseModelPackedPixel packed_pixel
/// \ingroup ColorBaseModel
/// \brief A heterogeneous color base whose elements are reference proxies to channels in a pixel. Models ColorBaseValueConcept. This class is used to model packed pixels, such as 16-bit packed RGB.

/**
   \defgroup PixelModelPackedPixel packed_pixel
   \ingroup PixelModel
   \brief A heterogeneous pixel used to represent packed pixels with non-byte-aligned channels. Models PixelValueConcept

   Example:
   \code
   typedef packed_pixel_type<uint16_t, mpl::vector3_c<unsigned,5,6,5>, rgb_layout_t>::type rgb565_pixel_t;
   BOOST_STATIC_ASSERT((sizeof(rgb565_pixel_t)==2));

   rgb565_pixel_t r565;
   get_color(r565,red_t())   = 31;
   get_color(r565,green_t()) = 63;
   get_color(r565,blue_t())  = 31;
   assert(r565 == rgb565_pixel_t((uint16_t)0xFFFF));
   \endcode
 */

/// \ingroup ColorBaseModelPackedPixel PixelModelPackedPixel PixelBasedModel
/// \brief Heterogeneous pixel value whose channel references can be constructed from the pixel bitfield and their index. Models ColorBaseValueConcept, PixelValueConcept, PixelBasedConcept
/// Typical use for this is a model of a packed pixel (like 565 RGB)
template <typename BitField,      // A type that holds the bits of the pixel. Typically an integral type, like boost::uint16_t
          typename ChannelRefVec, // An MPL vector whose elements are packed channels. They must be constructible from BitField. GIL uses packed_channel_reference
          typename Layout>
// Layout defining the color space and ordering of the channels. Example value: rgb_layout_t
struct packed_pixel
{
        BitField _bitfield;

        typedef Layout layout_t;
        typedef packed_pixel value_type;
        typedef value_type&           reference;
        typedef const value_type&     const_reference;

        BOOST_STATIC_CONSTANT( bool, is_mutable = channel_traits<typename mpl::front<ChannelRefVec>::type>::is_mutable );

        packed_pixel() {}
        explicit packed_pixel( const BitField& bitfield ) : _bitfield( bitfield ) {}

        // Construct from another compatible pixel type
        packed_pixel( const packed_pixel& p ) : _bitfield( p._bitfield ) {}
        template <typename P>
        packed_pixel( const P& p, typename enable_if_c<is_pixel<P>::value>::type* d = 0 )            { check_compatible<P>(); static_copy( p, *this ); }
        packed_pixel( int chan0, int chan1 ) : _bitfield( 0 )
        {
                BOOST_STATIC_ASSERT( ( num_channels<packed_pixel>::value == 2 ) );
                at_c<0>( *this ) = chan0; at_c<1>( *this ) = chan1;
        }

        packed_pixel( int chan0, int chan1, int chan2 ) : _bitfield( 0 )
        {
                BOOST_STATIC_ASSERT( ( num_channels<packed_pixel>::value == 3 ) );
                at_c<0>( *this ) = chan0; at_c<1>( *this ) = chan1; at_c<2>( *this ) = chan2;
        }

        packed_pixel( int chan0, int chan1, int chan2, int chan3 ) : _bitfield( 0 )
        {
                BOOST_STATIC_ASSERT( ( num_channels<packed_pixel>::value == 4 ) );
                at_c<0>( *this ) = chan0; at_c<1>( *this ) = chan1; at_c<2>( *this ) = chan2; at_c<3>( *this ) = chan3;
        }

        packed_pixel( int chan0, int chan1, int chan2, int chan3, int chan4 ) : _bitfield( 0 )
        {
                BOOST_STATIC_ASSERT( ( num_channels<packed_pixel>::value == 5 ) );
                at_c<0>( *this ) = chan0; at_c<1>( *this ) = chan1; at_c<2>( *this ) = chan2; at_c<3>( *this ) = chan3;  at_c<4>( *this ) = chan4;
        }

        packed_pixel& operator=( const packed_pixel& p ) { _bitfield = p._bitfield; return *this; }

        template <typename P>
        packed_pixel& operator=( const P& p ) { assign( p, mpl::bool_<is_pixel<P>::value>() ); return *this; }
        template <typename P>
        bool operator==( const P& p ) const { return equal( p, mpl::bool_<is_pixel<P>::value>() ); }

        template <typename P>
        bool operator!=( const P& p ) const { return !( *this == p ); }

        private:
                template <typename Pixel>
                static void check_compatible() { gil_function_requires<PixelsCompatibleConcept<Pixel, packed_pixel> >(); }
                template <typename Pixel>
                void assign( const Pixel& p, mpl::true_ ) { check_compatible<Pixel>(); static_copy( p, *this ); }
                template <typename Pixel>
                bool equal( const Pixel& p, mpl::true_ ) const { check_compatible<Pixel>(); return static_equal( *this, p ); }

                // Support for assignment/equality comparison of a channel with a grayscale pixel
                static void check_gray() {  BOOST_STATIC_ASSERT( ( is_same<typename Layout::color_space_t, gray_t>::value ) ); }
                template <typename Channel>
                void assign( const Channel& chan, mpl::false_ ) { check_gray(); at_c<0>( *this ) = chan; }
                template <typename Channel>
                bool equal( const Channel& chan, mpl::false_ ) const { check_gray(); return at_c<0>( *this ) == chan; }

        public:
                packed_pixel&  operator=( int chan )        { check_gray(); at_c<0>( *this ) = chan; return *this; }
                bool operator          ==( int chan ) const { check_gray(); return at_c<0>( *this ) == chan; }
};

/////////////////////////////
//  ColorBasedConcept
/////////////////////////////

template <typename BitField, typename ChannelRefVec, typename Layout, int K>
struct kth_element_type<packed_pixel<BitField, ChannelRefVec, Layout>, K> : public mpl::at_c<ChannelRefVec, K> {};

template <typename BitField, typename ChannelRefVec, typename Layout, int K>
struct kth_element_reference_type<packed_pixel<BitField, ChannelRefVec, Layout>, K> : public mpl::at_c<ChannelRefVec, K> {};

template <typename BitField, typename ChannelRefVec, typename Layout, int K>
struct kth_element_const_reference_type<packed_pixel<BitField, ChannelRefVec, Layout>, K>
{
        typedef typename channel_traits<typename mpl::at_c<ChannelRefVec, K>::type>::const_reference type;
};

template <int K, typename P, typename C, typename L>
inline
typename kth_element_reference_type<packed_pixel<P, C, L>, K>::type at_c( packed_pixel<P, C, L>& p )
{
        return typename kth_element_reference_type<packed_pixel<P, C, L>, K>::type( &p._bitfield );
}

template <int K, typename P, typename C, typename L>
inline
typename kth_element_const_reference_type<packed_pixel<P, C, L>, K>::type at_c( const packed_pixel<P, C, L>& p )
{
        return typename kth_element_const_reference_type<packed_pixel<P, C, L>, K>::type( &p._bitfield );
}

/////////////////////////////
//  PixelConcept
/////////////////////////////

// Metafunction predicate that flags packed_pixel as a model of PixelConcept. Required by PixelConcept
template <typename BitField, typename ChannelRefVec, typename Layout>
struct is_pixel<packed_pixel<BitField, ChannelRefVec, Layout> > : public mpl::true_ {};

/////////////////////////////
//  PixelBasedConcept
/////////////////////////////

template <typename P, typename C, typename Layout>
struct color_space_type<packed_pixel<P, C, Layout> >
{
        typedef typename Layout::color_space_t type;
};

template <typename P, typename C, typename Layout>
struct channel_mapping_type<packed_pixel<P, C, Layout> >
{
        typedef typename Layout::channel_mapping_t type;
};

template <typename P, typename C, typename Layout>
struct is_planar<packed_pixel<P, C, Layout> > : mpl::false_ {};

////////////////////////////////////////////////////////////////////////////////
///
/// Support for interleaved iterators over packed pixel
///
////////////////////////////////////////////////////////////////////////////////

/// \defgroup PixelIteratorModelPackedInterleavedPtr Pointer to packed_pixel<P,CR,Layout>
/// \ingroup PixelIteratorModel
/// \brief Iterators over interleaved pixels.
/// The pointer packed_pixel<P,CR,Layout>* is used as an iterator over interleaved pixels of packed format. Models PixelIteratorConcept, HasDynamicXStepTypeConcept, MemoryBasedIteratorConcept

template <typename P, typename C, typename L>
struct iterator_is_mutable<packed_pixel<P, C, L>*> : public mpl::bool_<packed_pixel<P, C, L>::is_mutable> {};
template <typename P, typename C, typename L>
struct iterator_is_mutable<const packed_pixel<P, C, L>*> : public mpl::false_ {};

}
}    // namespace boost::gil

namespace boost {
template <typename P, typename C, typename L>
struct has_trivial_constructor<gil::packed_pixel<P, C, L> > : public has_trivial_constructor<P> {};
}
#endif