Pixel concepts (details)
========================

.. contents:: Table of Contents
    :local:


.. _concept-details-Pixel:

Pixel
-----

.. cpp:concept:: template <typename Pix> Pixel

    #. Refines the :cpp:concept:`template <typename T> Regular` concept.
    #. ``Pix::value_type`` models the :cpp:concept:`template <typename Val> Value` concept, is non-const and is not a reference.
    #. ``Pix::point_type`` models the :cpp:concept:`template <typename Pnt> Point` concept.
    #. ``Pix::image_type`` models the :cpp:concept:`template <typename Ima> Image` concept.
    #. ``Pix`` is consistant with ``point_type``, ``value_type`` and ``reference`` from ``image_type``.
    #. ``Pix`` provide methods ``value``, ``point`` and ``image``.

    **Notation**

    .. cpp:type::   value_type = Pix::value_type
    .. cpp:type::   point_type = Pix::point_type
    .. cpp:type::   image_type = Pix::image_type
    .. cpp:type::   reference = Pix::reference
    .. cpp:var::    Pix pix
    .. cpp:var::    Pix pix_cpy
    .. cpp:var::    const Pix cpix
    .. cpp:var::    const Pix t
    .. cpp:var::    const Pix u

    **Valid Expressions**

    - :cpp:expr:`pix()` returns an instance of :cpp:expr:`Pix`.
    - :cpp:expr:`cpix()` returns an instance of :cpp:expr:`const Pix`.

    - :cpp:expr:`pix_cpy(pix)` returns an instance of :cpp:expr:`Pix`.
    - :cpp:expr:`pix_cpy(cpix)` returns an instance of :cpp:expr:`Pix`.
    - :cpp:expr:`pix_cpy(move(pix))` returns an instance of :cpp:expr:`Pix`.

    - :cpp:expr:`pix_cpy = pix` returns an instance of :cpp:expr:`Pix&`.
    - :cpp:expr:`pix_cpy = cpix` returns an instance of :cpp:expr:`Pix&`.
    - :cpp:expr:`pix_cpy = move(pix)` returns an instance of :cpp:expr:`Pix&`.

    - :cpp:expr:`t == u` return-type models :cpp:concept:`template<typename B> Boolean`.
    - :cpp:expr:`t != u` return-type models :cpp:concept:`template<typename B> Boolean`.
    - :cpp:expr:`u == t` return-type models :cpp:concept:`template<typename B> Boolean`.
    - :cpp:expr:`u != t` return-type models :cpp:concept:`template<typename B> Boolean`.

    - :cpp:expr:`pix.value()` returns :cpp:expr:`reference`.
    - :cpp:expr:`pix.point()` returns :cpp:expr:`point_type`.
    - :cpp:expr:`pix.image()` returns :cpp:expr:`image_type`.

    - :cpp:expr:`cpix.value()` returns :cpp:expr:`const reference`.
    - :cpp:expr:`cpix.point()` returns :cpp:expr:`const point_type`.
    - :cpp:expr:`cpix.image()` returns :cpp:expr:`const image_type`.

    **Possible implementation**

    .. code:: cpp

        template<typename P, Pix = remove_cvref<P>>
        concept Pixel = requires Regular<Pix> &&
                        
                        requires {
                            typename Pix::value_type;
                            typename Pix::point_type;
                            typename Pix::image_type;
                            typename Pix::reference;
                        } &&

                        Value<Pix::value_type> &&
                        Point<Pix::point_type> &&
                        Image<Pix::image_type> &&
                        
                        Same<Pix::value_type, Pix::image_type::value_type> &&
                        Same<Pix::point_type, Pix::image_type::point_type> &&
                        Same<Pix::reference, Pix::image_type::reference> &&

                        !is_const_v<Pix::value_type> &&
                        !is_reference_v<Pix::value_type> &&

                        requires(const Pix cpix, Pix pix) {
                            { cpix.value() } -> const reference;
                            { cpix.point() } -> const point_type;
                            { cpix.image() } -> const image_type;
                            { pix.value() }  -> reference;
                            { pix.point() }  -> point_type;
                            { pix.image() }  -> image_type;
                        };


.. _concept-details-TransformedPixel:

TransformedPixel
----------------

.. cpp:concept:: template <typename ToPix, typename FromPix> TransformedPixel

    #. Refines the :cpp:concept:`template <typename Pix> Pixel` concept.
    #. ``ToPix::from_pixel_type`` models the :cpp:concept:`template <typename Pix> Pixel` concept.

    **Possible implementation**

    .. code:: cpp

        template<   typename TP, typename FP,
                    ToPix = remove_cvref<TP>, FromPix = remove_cvref<FP>>
        concept TransformedPixel =  Pixel<ToPix> &&
                                    Pixel<FromPix> &&

                                    requires {
                                        typename ToPix::from_pixel_type
                                    } &&
                                    Same<ToPix::from_pixel_type, FromPix>;


.. _concept-details-ProjectedPixel:

ProjectedPixel
--------------

.. cpp:concept:: template <typename ToPix, typename FromPix> ProjectedPixel

    #. Refines the :cpp:concept:`template <typename ToPix, typename FromPix> TransformedPixel` concept.

    **Possible implementation**

    .. code:: cpp

        template<typename ToPix, typename FromPix, PPix = remove_cvref<ToPix>>
        concept ProjectedPixel =    TransformedPixel<ToPix, FromPix>;


.. _concept-details-ZippedPixel:

ZippedPixel
-----------

.. cpp:concept:: template <typename ZPix, typename... FromPixs> ZippedPixel

    #. Refines the :cpp:concept:`template <typename Pix> Pixel` concept.
    #. ``FromPixs...`` models the :cpp:concept:`template <typename Pix> Pixel` concept.
    #. Let ``ZPix::zipped_pixel_type_list`` be the list of types zipped.

    **Possible implementation**

    .. code:: cpp

        template <typename...>
        struct basic_type_list {};

        template<   typename ZP, typename... FromPixs,
                    ZPix = remove_cvref<ZPix>>
        concept ZippedPixel =
            Pixel<ZPix> &&
            Pixel<FromPixs>... &&

            requires {
                typename ZPix::zipped_pixel_type_list<FromPixs...>
            } &&

            ConvertibleTo<
                ZPix::zipped_pixel_type_list<FromPixs...>,
                basic_type_list<FromPixs...>>;