AOO410/main/basebmp/inc/basebmp/pixelformatadapters.hxx

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#ifndef INCLUDED_BASEBMP_PIXELFORMATADAPTERS_HXX
#define INCLUDED_BASEBMP_PIXELFORMATADAPTERS_HXX

#include <basebmp/accessortraits.hxx>
#include <basebmp/accessoradapters.hxx>

#include <vigra/metaprogramming.hxx>

namespace basebmp
{

// convenience functionality, providing everything necessary for a new
// pixel format. simply plug in two conversion functors from/to a
// common color format.

/** Accessor selection metafunction, used to wrap a given accessor
    with one converting between the pixel and color types

    Use the nested template's typedef type, to retrieve an
    AccessorAdapter which operates on a pixel value accessor, and
    provides color values to the outside.

    Nested like this, to avoid template template parameters at other
    places: an instantiated version of AccessorSelector can be passed
    to other templates, which in turn can invoke the nested meta
    function.
 */
template< typename Getter, 
          typename Setter > struct AccessorSelector
{
    template< typename Accessor > struct wrap_accessor
    {
        typedef UnaryFunctionAccessorAdapter< Accessor, 
                                              Getter,
                                              Setter > type;
    };
};

//-----------------------------------------------------------------------------

/** Convert color value to pixel data type
 */    
template< class Accessor, typename DataType > struct ColorConvert
{
    DataType operator()( const Accessor&               acc,
                         typename Accessor::value_type v ) const
    {
        return acc.setter(v);
    }
};

//-----------------------------------------------------------------------------

/** Macro generates partial specialization for color-conversion
    UnaryFunctionAccessorAdapter, and the given getter/setter functors
 */
#define BASEBMP_SPECIALIZE_ACCESSORTRAITS(Getter,Setter)          \
template< class Accessor > struct AccessorTraits<                 \
    UnaryFunctionAccessorAdapter< Accessor,                       \
                                  Getter,                         \
                                  Setter > >                      \
{                                                                 \
    typedef typename Accessor::value_type          data_type;     \
    typedef UnaryFunctionAccessorAdapter<                         \
        Accessor,                                                 \
        Getter,                                                   \
        Setter >                                   accessor_type; \
    typedef typename accessor_type::value_type     value_type;    \
    typedef ColorConvert< accessor_type,                          \
                          data_type >              color_lookup;  \
    typedef Accessor                               raw_accessor;  \
    typedef vigra::VigraFalseType                  xor_accessor;  \
    template< class MaskAccessor,                                 \
              class Iterator,                                     \
              class MaskIterator > struct          masked_accessor\
    { typedef vigra::VigraFalseType type; };                      \
}

} // namespace basebmp

#endif /* INCLUDED_BASEBMP_PIXELFORMATADAPTERS_HXX */