boost/gil/extension/toolbox/metafunctions/channel_view.hpp

   1 //
   2 // Copyright 2010 Fabien Castan, Christian Henning
   3 //
   4 // Distributed under the Boost Software License, Version 1.0
   5 // See accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt
   7 //
   8 #ifndef BOOST_GIL_EXTENSION_TOOLBOX_CHANNEL_VIEW_HPP
   9 #define BOOST_GIL_EXTENSION_TOOLBOX_CHANNEL_VIEW_HPP
  10
  11 #include <boost/gil/image_view_factory.hpp>
  12
  13 namespace boost {
  14 namespace gil {
  15
  16 template <typename Channel, typename View>
  17 struct channel_type_to_index
  18 {
  19     static constexpr int value = detail::type_to_index
  20         <
  21             typename color_space_type<View>::type, // color (Boost.MP11-compatible list)
  22             Channel                                // channel type
  23         >::value;                                  // index of the channel in the color (Boost.MP11-compatible list)
  24 };
  25
  26 template<typename Channel, typename View>
  27 struct channel_view_type : kth_channel_view_type
  28     <
  29         channel_type_to_index<Channel, View>::value,
  30         View
  31     >
  32 {
  33     static constexpr int index = channel_type_to_index
  34         <
  35             Channel,
  36             View
  37         >::value;
  38
  39     using parent_t = kth_channel_view_type<index, View>;
  40     using type = typename parent_t::type;
  41
  42     static type make( const View& src )
  43     {
  44         return parent_t::make( src );
  45     }
  46 };
  47
  48 /// \ingroup ImageViewTransformationsKthChannel
  49 template<typename Channel, typename View>
  50 auto channel_view(View const& src)
  51     -> typename channel_view_type<Channel, View>::type
  52 {
  53    return channel_view_type<Channel, View>::make(src);
  54 }
  55
  56 }} // namespace boost::gil
  57
  58 #endif