boost::gil::ColorBaseConcept
A color base is a container of color elements (such as channels, channel references or channel pointers).
Synopsis
Declared in <boost/gil/concepts/color_base.hpp>
template<typename ColorBase>
struct ColorBaseConcept;Description
The most common use of color base is in the implementation of a pixel, in which case the color elements are channel values. The color base concept, however, can be used in other scenarios. For example, a planar pixel has channels that are not contiguous in memory. Its reference is a proxy class that uses a color base whose elements are channel references. Its iterator uses a color base whose elements are channel iterators.
A color base must have an associated layout (which consists of a color space, as well as an ordering of the channels). There are two ways to index the elements of a color base: A physical index corresponds to the way they are ordered in memory, and a semantic index corresponds to the way the elements are ordered in their color space. For example, in the RGB color space the elements are ordered as {red_t, green_t, blue_t}. For a color base with a BGR layout, the first element in physical ordering is the blue element, whereas the first semantic element is the red one. Models of ColorBaseConcept are required to provide the at_c<K>(ColorBase) function, which allows for accessing the elements based on their physical order. GIL provides a semantic_at_c<K>(ColorBase) function (described later) which can operate on any model of ColorBaseConcept and returns the corresponding semantic element.
concept ColorBaseConcept<typename T> : CopyConstructible<T>, EqualityComparable<T>
{
// a GIL layout (the color space and element permutation)
typename layout_t;
// The type of K-th element
template <int K>
struct kth_element_type;
where Metafunction<kth_element_type>;
// The result of at_c
template <int K>
struct kth_element_const_reference_type;
where Metafunction<kth_element_const_reference_type>;
template <int K>
kth_element_const_reference_type<T,K>::type at_c(T);
// Copy-constructible and equality comparable with other compatible color bases
template <ColorBaseConcept T2> where { ColorBasesCompatibleConcept<T,T2> }
T::T(T2);
template <ColorBaseConcept T2> where { ColorBasesCompatibleConcept<T,T2> }
bool operator==(const T&, const T2&);
template <ColorBaseConcept T2> where { ColorBasesCompatibleConcept<T,T2> }
bool operator!=(const T&, const T2&);
};