bmp/detail/is_allowed.hpp

0001 //
0002 // Copyright 2009 Christian Henning
0003 //
0004 // Distributed under the Boost Software License, Version 1.0
0005 // See accompanying file LICENSE_1_0.txt or copy at
0006 // http://www.boost.org/LICENSE_1_0.txt
0007 //
0008 #ifndef BOOST_GIL_EXTENSION_IO_BMP_DETAIL_IS_ALLOWED_HPP
0009 #define BOOST_GIL_EXTENSION_IO_BMP_DETAIL_IS_ALLOWED_HPP
0010
0011 #include <boost/gil/extension/io/bmp/tags.hpp>
0012 #include <boost/gil/channel.hpp>
0013
0014 #include <type_traits>
0015
0016 namespace boost { namespace gil { namespace detail {
0017
0018 template< typename View >
0019 bool is_allowed( const image_read_info< bmp_tag >& info
0020                , std::true_type   // is read_and_no_convert
0021                )
0022 {
0023     bmp_bits_per_pixel::type src_bits_per_pixel = 0;
0024
0025     switch( info._bits_per_pixel )
0026     {
0027         case 1:
0028         case 4:
0029         case 8:
0030         {
0031             if(  info._header_size == bmp_header_size::_win32_info_size
0032               && info._compression != bmp_compression::_rle8
0033               && info._compression != bmp_compression::_rle4
0034               )
0035             {
0036                 src_bits_per_pixel = 32;
0037             }
0038             else
0039             {
0040                 src_bits_per_pixel = 24;
0041             }
0042
0043             break;
0044         }
0045
0046         case 15:
0047         case 16:
0048         {
0049             src_bits_per_pixel = 24;
0050
0051             break;
0052         }
0053
0054         case 24:
0055         case 32:
0056         {
0057             src_bits_per_pixel = info._bits_per_pixel;
0058
0059             break;
0060         }
0061         default:
0062         {
0063             io_error( "Pixel size not supported." );
0064         }
0065     }
0066
0067     using channel_t = typename channel_traits<typename element_type<typename View::value_type>::type>::value_type;
0068     bmp_bits_per_pixel::type dst_bits_per_pixel = detail::unsigned_integral_num_bits< channel_t >::value
0069                                                 * num_channels< View >::value;
0070
0071     return ( dst_bits_per_pixel == src_bits_per_pixel );
0072 }
0073
0074 template< typename View >
0075 bool is_allowed( const image_read_info< bmp_tag >& /* info */
0076                , std::false_type  // is read_and_convert
0077                )
0078 {
0079     return true;
0080 }
0081
0082 } // namespace detail
0083 } // namespace gil
0084 } // namespace boost
0085
0086 #endif