packed_pixel.hpp

//
// 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_PACKED_PIXEL_HPP
#define BOOST_GIL_PACKED_PIXEL_HPP

#include <boost/gil/pixel.hpp>

#include <boost/core/ignore_unused.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/mpl/front.hpp>

#include <functional>
#include <type_traits>

namespace boost { namespace gil {




template <typename BitField,      // A type that holds the bits of the pixel. Typically an integral type, like std::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;

    using layout_t = Layout;
    using value_type = packed_pixel<BitField, ChannelRefVec, Layout>;
    using reference = value_type&;
    using const_reference = value_type const&;

    static constexpr 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(P const& p,
        typename std::enable_if<is_pixel<P>::value>::type* /*dummy*/ = nullptr)
    {
        check_compatible<P>();
        static_copy(p, *this);
    }

    packed_pixel(int chan0, int chan1) : _bitfield(0) {
        static_assert(num_channels<packed_pixel>::value == 2, "");
        gil::at_c<0>(*this)=chan0; gil::at_c<1>(*this)=chan1;
    }
    packed_pixel(int chan0, int chan1, int chan2) : _bitfield(0) {
        static_assert(num_channels<packed_pixel>::value == 3, "");
        gil::at_c<0>(*this) = chan0;
        gil::at_c<1>(*this) = chan1;
        gil::at_c<2>(*this) = chan2;
    }
    packed_pixel(int chan0, int chan1, int chan2, int chan3) : _bitfield(0) {
        static_assert(num_channels<packed_pixel>::value == 4, "");
        gil::at_c<0>(*this)=chan0; gil::at_c<1>(*this)=chan1; gil::at_c<2>(*this)=chan2; gil::at_c<3>(*this)=chan3;
    }
    packed_pixel(int chan0, int chan1, int chan2, int chan3, int chan4) : _bitfield(0) {
        static_assert(num_channels<packed_pixel>::value == 5, "");
        gil::at_c<0>(*this)=chan0; gil::at_c<1>(*this)=chan1; gil::at_c<2>(*this)=chan2; gil::at_c<3>(*this)=chan3; gil::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()
    {
        static_assert(is_same<typename Layout::color_space_t, gray_t>::value, "");
    }
    template <typename Channel> void assign(const Channel& chan, mpl::false_)       { check_gray(); gil::at_c<0>(*this)=chan; }
    template <typename Channel> bool equal (const Channel& chan, mpl::false_) const { check_gray(); return gil::at_c<0>(*this)==chan; }
public:
    packed_pixel&  operator= (int chan)       { check_gray(); gil::at_c<0>(*this)=chan; return *this; }
    bool           operator==(int chan) const { check_gray(); return gil::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>
{
    using type = typename channel_traits<typename mpl::at_c<ChannelRefVec,K>::type>::const_reference;
};

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> > {
    using type = typename Layout::color_space_t;
};

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

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




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