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Diffstat (limited to 'boost/gil/extension/io/bmp/detail/reader_backend.hpp')
| -rw-r--r-- | boost/gil/extension/io/bmp/detail/reader_backend.hpp | 258 |
1 files changed, 258 insertions, 0 deletions
diff --git a/boost/gil/extension/io/bmp/detail/reader_backend.hpp b/boost/gil/extension/io/bmp/detail/reader_backend.hpp new file mode 100644 index 0000000000..589a5e3c4f --- /dev/null +++ b/boost/gil/extension/io/bmp/detail/reader_backend.hpp @@ -0,0 +1,258 @@ +/* + Copyright 2012 Christian Henning + 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). +*/ + +/*************************************************************************************************/ + +#ifndef BOOST_GIL_EXTENSION_IO_BMP_DETAIL_READER_BACKEND_HPP +#define BOOST_GIL_EXTENSION_IO_BMP_DETAIL_READER_BACKEND_HPP + +//////////////////////////////////////////////////////////////////////////////////////// +/// \file +/// \brief +/// \author Christian Henning \n +/// +/// \date 2012 \n +/// +//////////////////////////////////////////////////////////////////////////////////////// + +#include <boost/gil/extension/io/bmp/tags.hpp> + +namespace boost { namespace gil { + +#if BOOST_WORKAROUND(BOOST_MSVC, >= 1400) +#pragma warning(push) +#pragma warning(disable:4512) //assignment operator could not be generated +#endif + +/// Color channel mask +struct bit_field +{ + unsigned int mask; // Bit mask at corresponding position + unsigned int width; // Bit width of the mask + unsigned int shift; // Bit position from right to left +}; + +/// BMP color masks +struct color_mask +{ + bit_field red; // Red bits + bit_field green; // Green bits + bit_field blue; // Blue bits +}; + + +/// +/// BMP Backend +/// +template< typename Device > +struct reader_backend< Device + , bmp_tag + > +{ +public: + + typedef bmp_tag format_tag_t; + +public: + + reader_backend( const Device& io_dev + , const image_read_settings< bmp_tag >& settings + ) + : _io_dev ( io_dev ) + , _settings( settings ) + , _info() + , _scanline_length( 0 ) + , _palette() + { + read_header(); + + if( _settings._dim.x == 0 ) + { + _settings._dim.x = _info._width; + } + + if( _settings._dim.y == 0 ) + { + _settings._dim.y = _info._height; + } + } + + void read_header() + { + // the magic number used to identify the BMP file: + // 0x42 0x4D (ASCII code points for B and M) + if( _io_dev.read_uint16() == 0x424D ) + { + io_error( "Wrong magic number for bmp file." ); + } + + // the size of the BMP file in bytes + _io_dev.read_uint32(); + + // reserved; actual value depends on the application that creates the image + _io_dev.read_uint16(); + // reserved; actual value depends on the application that creates the image + _io_dev.read_uint16(); + + _info._offset = _io_dev.read_uint32(); + + + // bitmap information + + // the size of this header ( 40 bytes ) + _info._header_size = _io_dev.read_uint32(); + + if( _info._header_size == bmp_header_size::_win32_info_size ) + { + _info._width = _io_dev.read_uint32(); + _info._height = _io_dev.read_uint32(); + + if (_info._height < 0) + { + _info._height = -_info._height; + _info._top_down = true; + } + + // the number of color planes being used. Must be set to 1. + _io_dev.read_uint16(); + + _info._bits_per_pixel = _io_dev.read_uint16(); + + _info._compression = _io_dev.read_uint32(); + + _info._image_size = _io_dev.read_uint32(); + + _info._horizontal_resolution = _io_dev.read_uint32(); + _info._vertical_resolution = _io_dev.read_uint32(); + + _info._num_colors = _io_dev.read_uint32(); + _info._num_important_colors = _io_dev.read_uint32(); + + } + else if( _info._header_size == bmp_header_size::_os2_info_size ) + { + _info._width = static_cast< bmp_image_width::type >( _io_dev.read_uint16() ); + _info._height = static_cast< bmp_image_height::type >( _io_dev.read_uint16() ); + + // the number of color planes being used. Must be set to 1. + _io_dev.read_uint16(); + + _info._bits_per_pixel = _io_dev.read_uint16(); + + _info._compression = bmp_compression::_rgb; + + // not used + _info._image_size = 0; + _info._horizontal_resolution = 0; + _info._vertical_resolution = 0; + _info._num_colors = 0; + _info._num_important_colors = 0; + } + else if (_info._header_size > bmp_header_size::_win32_info_size) + { + // could be v4 or v5 + // see MSDN: Bitmap Header Types ( BITMAPV4HEADER or BITMAPV5HEADER ) + + _info._width = _io_dev.read_uint32(); + _info._height = _io_dev.read_uint32(); + + // the number of color planes being used. Must be set to 1. + _io_dev.read_uint16(); + + _info._bits_per_pixel = _io_dev.read_uint16(); + + _info._compression = _io_dev.read_uint32(); + + _info._image_size = _io_dev.read_uint32(); + + _info._horizontal_resolution = _io_dev.read_uint32(); + _info._vertical_resolution = _io_dev.read_uint32(); + + _info._num_colors = _io_dev.read_uint32(); + _info._num_important_colors = _io_dev.read_uint32(); + } + else + { + io_error( "Invalid BMP info header." ); + } + + _info._valid = true; + } + + void read_palette() + { + int entries = this->_info._num_colors; + + if( entries == 0 ) + { + entries = 1u << this->_info._bits_per_pixel; + } + + _palette.resize( entries, rgba8_pixel_t(0, 0, 0, 0)); + + for( int i = 0; i < entries; ++i ) + { + get_color( _palette[i], blue_t() ) = _io_dev.read_uint8(); + get_color( _palette[i], green_t() ) = _io_dev.read_uint8(); + get_color( _palette[i], red_t() ) = _io_dev.read_uint8(); + + // there are 4 entries when windows header + // but 3 for os2 header + if( _info._header_size == bmp_header_size::_win32_info_size ) + { + _io_dev.read_uint8(); + } + + } // for + } + + /// Check if image is large enough. + void check_image_size( const point_t& img_dim ) + { + if( _settings._dim.x > 0 ) + { + if( img_dim.x < _settings._dim.x ) { io_error( "Supplied image is too small" ); } + } + else + { + if( img_dim.x < _info._width ) { io_error( "Supplied image is too small" ); } + } + + + if( _settings._dim.y > 0 ) + { + if( img_dim.y < _settings._dim.y ) { io_error( "Supplied image is too small" ); } + } + else + { + if( img_dim.y < _info._height ) { io_error( "Supplied image is too small" ); } + } + } + +public: + + Device _io_dev; + + image_read_settings< bmp_tag > _settings; + image_read_info< bmp_tag > _info; + + std::size_t _scanline_length; + + ///@todo make it an image. + std::vector< rgba8_pixel_t > _palette; + + color_mask _mask; +}; + +#if BOOST_WORKAROUND(BOOST_MSVC, >= 1400) +#pragma warning(pop) +#endif + +} // namespace gil +} // namespace boost + +#endif |