any_image_view.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_DYNAMICIMAGE_ANY_IMAGEVIEW_HPP
#define GIL_DYNAMICIMAGE_ANY_IMAGEVIEW_HPP

////////////////////////////////////////////////////////////////////////////////////////
/// \file               
/// \brief Support for run-time instantiated image view
/// \author Lubomir Bourdev and Hailin Jin \n
///         Adobe Systems Incorporated
///
///
////////////////////////////////////////////////////////////////////////////////////////

#include "variant.hpp"
#include "../../image_view.hpp"
#include "../../image.hpp"

namespace boost { namespace gil {

namespace detail {
    template <typename View> struct get_const_t { typedef typename View::const_t type; };
    template <typename Views> struct views_get_const_t : public mpl::transform<Views, get_const_t<mpl::_1> > {};
}
template <typename View> struct dynamic_xy_step_type;
template <typename View> struct dynamic_xy_step_transposed_type;

namespace detail {
    struct any_type_get_num_channels {   // works for both image_view and image
        typedef int result_type;
        template <typename T> result_type operator()(const T& v) const { return num_channels<T>::value; }
    };
    struct any_type_get_dimensions {    // works for both image_view and image
        typedef point2<std::ptrdiff_t> result_type;
        template <typename T> result_type operator()(const T& v) const { return v.dimensions(); }
    };
}

////////////////////////////////////////////////////////////////////////////////////////
/// CLASS any_image_view
///
/// \ingroup ImageViewModel
/// \brief Represents a run-time specified image view. Models HasDynamicXStepTypeConcept, HasDynamicYStepTypeConcept, Note that this class does NOT model ImageViewConcept
///
/// Represents a view whose type (color space, layout, planar/interleaved organization, etc) can be specified at run time.
/// It is the runtime equivalent of \p image_view.
/// Some of the requirements of ImageViewConcept, such as the \p value_type typedef cannot be fulfilled, since the language does not allow runtime type specification.
/// Other requirements, such as access to the pixels, would be inefficient to provide. Thus \p any_image_view does not fully model ImageViewConcept.
/// However, many algorithms provide overloads taking runtime specified views and thus in many cases \p any_image_view can be used in places taking a view.
///
/// To perform an algorithm on any_image_view, put the algorithm in a function object and invoke it by calling \p apply_operation(runtime_view, algorithm_fn);
////////////////////////////////////////////////////////////////////////////////////////
template <typename ImageViewTypes>
class any_image_view : public variant<ImageViewTypes> {
    typedef variant<ImageViewTypes> parent_t;
public:
    typedef any_image_view<typename detail::views_get_const_t<ImageViewTypes>::type> const_t;
    typedef std::ptrdiff_t x_coord_t;
    typedef std::ptrdiff_t y_coord_t;
    typedef point2<std::ptrdiff_t> point_t;

    any_image_view()                                                          : parent_t() {}
    template <typename T> explicit any_image_view(const T& obj)               : parent_t(obj) {}
    any_image_view(const any_image_view& v)                                   : parent_t((const parent_t&)v)    {}

    template <typename T> any_image_view& operator=(const T& obj)             { parent_t::operator=(obj); return *this; }
    any_image_view&                       operator=(const any_image_view& v)  { parent_t::operator=((const parent_t&)v); return *this;}

    std::size_t num_channels()  const { return apply_operation(*this, detail::any_type_get_num_channels()); }
    point_t     dimensions()    const { return apply_operation(*this, detail::any_type_get_dimensions()); }
    x_coord_t   width()         const { return dimensions().x; }
    y_coord_t   height()        const { return dimensions().y; }
};

/////////////////////////////
//  HasDynamicXStepTypeConcept
/////////////////////////////

template <typename IVTypes>
struct dynamic_x_step_type<any_image_view<IVTypes> > {
    typedef any_image_view<typename mpl::transform<IVTypes, dynamic_x_step_type<mpl::_1> >::type> type;
};

/////////////////////////////
//  HasDynamicYStepTypeConcept
/////////////////////////////

template <typename IVTypes>
struct dynamic_y_step_type<any_image_view<IVTypes> > {
    typedef any_image_view<typename mpl::transform<IVTypes, dynamic_y_step_type<mpl::_1> >::type> type;
};

template <typename IVTypes>
struct dynamic_xy_step_type<any_image_view<IVTypes> > {
    typedef any_image_view<typename mpl::transform<IVTypes, dynamic_xy_step_type<mpl::_1> >::type> type;
};

template <typename IVTypes>
struct dynamic_xy_step_transposed_type<any_image_view<IVTypes> > {
    typedef any_image_view<typename mpl::transform<IVTypes, dynamic_xy_step_transposed_type<mpl::_1> >::type> type;
};

} }  // namespace boost::gil

#endif