boost/gil/extension/io/bmp/detail/is_allowed.hpp

   1 //
   2 // Copyright 2009 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_IO_BMP_DETAIL_IS_ALLOWED_HPP
   9 #define BOOST_GIL_EXTENSION_IO_BMP_DETAIL_IS_ALLOWED_HPP
  10
  11 #include <boost/gil/extension/io/bmp/tags.hpp>
  12 #include <boost/gil/channel.hpp>
  13
  14 #include <type_traits>
  15
  16 namespace boost { namespace gil { namespace detail {
  17
  18 template< typename View >
  19 bool is_allowed( const image_read_info< bmp_tag >& info
  20                , std::true_type   // is read_and_no_convert
  21                )
  22 {
  23     bmp_bits_per_pixel::type src_bits_per_pixel = 0;
  24
  25     switch( info._bits_per_pixel )
  26     {
  27         case 1:
  28         case 4:
  29         case 8:
  30         {
  31             if(  info._header_size == bmp_header_size::_win32_info_size
  32               && info._compression != bmp_compression::_rle8
  33               && info._compression != bmp_compression::_rle4
  34               )
  35             {
  36                 src_bits_per_pixel = 32;
  37             }
  38             else
  39             {
  40                 src_bits_per_pixel = 24;
  41             }
  42
  43             break;
  44         }
  45
  46         case 15:
  47         case 16:
  48         {
  49             src_bits_per_pixel = 24;
  50
  51             break;
  52         }
  53
  54         case 24:
  55         case 32:
  56         {
  57             src_bits_per_pixel = info._bits_per_pixel;
  58
  59             break;
  60         }
  61         default:
  62         {
  63             io_error( "Pixel size not supported." );
  64         }
  65     }
  66
  67     using channel_t = typename channel_traits<typename element_type<typename View::value_type>::type>::value_type;
  68     bmp_bits_per_pixel::type dst_bits_per_pixel = detail::unsigned_integral_num_bits< channel_t >::value
  69                                                 * num_channels< View >::value;
  70
  71     return ( dst_bits_per_pixel == src_bits_per_pixel );
  72 }
  73
  74 template< typename View >
  75 bool is_allowed( const image_read_info< bmp_tag >& /* info */
  76                , std::false_type  // is read_and_convert
  77                )
  78 {
  79     return true;
  80 }
  81
  82 } // namespace detail
  83 } // namespace gil
  84 } // namespace boost
  85
  86 #endif