//
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// Copyright 2007-2012 Christian Henning, Andreas Pokorny, Lubomir Bourdev
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//
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// Distributed under the Boost Software License, Version 1.0
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// See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt
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//
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#ifndef BOOST_GIL_EXTENSION_IO_JPEG_TAGS_HPP
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#define BOOST_GIL_EXTENSION_IO_JPEG_TAGS_HPP
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// taken from jpegxx - https://bitbucket.org/edd/jpegxx/src/ea2492a1a4a6/src/ijg_headers.hpp
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#ifndef BOOST_GIL_EXTENSION_IO_JPEG_C_LIB_COMPILED_AS_CPLUSPLUS
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extern "C" {
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#else
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// DONT_USE_EXTERN_C introduced in v7 of the IJG library.
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// By default the v7 IJG headers check for __cplusplus being defined and
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// wrap the content in an 'extern "C"' block if it's present.
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// When DONT_USE_EXTERN_C is defined, this wrapping is not performed.
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#ifndef DONT_USE_EXTERN_C
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#define DONT_USE_EXTERN_C 1
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#endif
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#endif
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#include <cstdio> // jpeglib doesn't know about FILE
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#include <jerror.h>
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#include <jpeglib.h>
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#ifndef BOOST_GIL_EXTENSION_IO_JPEG_C_LIB_COMPILED_AS_CPLUSPLUS
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}
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#endif
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#include <boost/gil/io/base.hpp>
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namespace boost { namespace gil {
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/// Defines jpeg tag.
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struct jpeg_tag : format_tag {};
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/// see http://en.wikipedia.org/wiki/JPEG for reference
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/// Defines type for image width property.
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struct jpeg_image_width : property_base< JDIMENSION > {};
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/// Defines type for image height property.
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struct jpeg_image_height : property_base< JDIMENSION > {};
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/// Defines type for number of components property.
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struct jpeg_num_components : property_base< int > {};
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/// Defines type for color space property.
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struct jpeg_color_space : property_base< J_COLOR_SPACE > {};
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/// Defines type for jpeg quality property.
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struct jpeg_quality : property_base< int >
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{
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static const type default_value = 100;
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};
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/// Defines type for data precision property.
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struct jpeg_data_precision : property_base< int > {};
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/// JFIF code for pixel size units
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struct jpeg_density_unit : property_base< UINT8 >
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{
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static const type default_value = 0;
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};
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/// pixel density
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struct jpeg_pixel_density : property_base< UINT16 >
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{
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static const type default_value = 0;
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};
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/// Defines type for dct ( discrete cosine transformation ) method property.
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struct jpeg_dct_method : property_base< J_DCT_METHOD >
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{
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static const type slow = JDCT_ISLOW;
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static const type fast = JDCT_IFAST;
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static const type floating_pt = JDCT_FLOAT;
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static const type fastest = JDCT_FASTEST;
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static const type default_value = slow;
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};
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/// Read information for jpeg images.
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///
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/// The structure is returned when using read_image_info.
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template<>
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struct image_read_info< jpeg_tag >
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{
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image_read_info()
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: _width ( 0 )
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, _height( 0 )
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, _num_components( 0 )
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, _color_space( J_COLOR_SPACE( 0 ))
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, _data_precision( 0 )
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, _density_unit ( 0 )
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, _x_density ( 0 )
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, _y_density ( 0 )
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, _pixel_width_mm ( 0.0 )
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, _pixel_height_mm( 0.0 )
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{}
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/// The image width.
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jpeg_image_width::type _width;
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/// The image height.
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jpeg_image_height::type _height;
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/// The number of channels.
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jpeg_num_components::type _num_components;
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/// The color space.
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jpeg_color_space::type _color_space;
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/// The width of channel.
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/// I believe this number is always 8 in the case libjpeg is built with 8.
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/// see: http://www.asmail.be/msg0055405033.html
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jpeg_data_precision::type _data_precision;
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/// Density conversion unit.
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jpeg_density_unit::type _density_unit;
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jpeg_pixel_density::type _x_density;
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jpeg_pixel_density::type _y_density;
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/// Real-world dimensions
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double _pixel_width_mm;
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double _pixel_height_mm;
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};
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/// Read settings for jpeg images.
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///
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/// The structure can be used for all read_xxx functions, except read_image_info.
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template<>
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struct image_read_settings< jpeg_tag > : public image_read_settings_base
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{
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/// Default constructor
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image_read_settings<jpeg_tag>()
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: image_read_settings_base()
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, _dct_method( jpeg_dct_method::default_value )
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{}
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/// Constructor
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/// \param top_left Top left coordinate for reading partial image.
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/// \param dim Dimensions for reading partial image.
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/// \param dct_method Specifies dct method.
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image_read_settings( const point_t& top_left
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, const point_t& dim
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, jpeg_dct_method::type dct_method = jpeg_dct_method::default_value
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)
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: image_read_settings_base( top_left
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, dim
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)
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, _dct_method( dct_method )
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{}
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/// The dct ( discrete cosine transformation ) method.
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jpeg_dct_method::type _dct_method;
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};
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/// Write information for jpeg images.
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///
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/// The structure can be used for write_view() function.
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template<>
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struct image_write_info< jpeg_tag >
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{
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/// Constructor
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/// \param quality Defines the jpeg quality.
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/// \param dct_method Defines the DCT method.
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/// \param density_unit Defines the density unit.
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/// \param x_density Defines the x density.
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/// \param y_density Defines the y density.
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image_write_info( const jpeg_quality::type quality = jpeg_quality::default_value
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, const jpeg_dct_method::type dct_method = jpeg_dct_method::default_value
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, const jpeg_density_unit::type density_unit = jpeg_density_unit::default_value
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, const jpeg_pixel_density::type x_density = jpeg_pixel_density::default_value
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, const jpeg_pixel_density::type y_density = jpeg_pixel_density::default_value
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)
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: _quality ( quality )
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, _dct_method( dct_method )
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, _density_unit( density_unit )
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, _x_density ( x_density )
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, _y_density ( y_density )
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{}
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/// The jpeg quality.
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jpeg_quality::type _quality;
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/// The dct ( discrete cosine transformation ) method.
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jpeg_dct_method::type _dct_method;
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/// Density conversion unit.
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jpeg_density_unit::type _density_unit;
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/// Pixel density dimensions.
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jpeg_pixel_density::type _x_density;
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jpeg_pixel_density::type _y_density;
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/// Sets the pixel dimensions.
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void set_pixel_dimensions( int image_width // in pixels
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, int image_height // in pixels
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, double pixel_width // in mm
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, double pixel_height // in mm
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)
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{
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_density_unit = 2; // dots per cm
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_x_density = round( image_width / ( pixel_width / 10 ));
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_y_density = round( image_height / ( pixel_height / 10 ));
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}
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private:
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UINT16 round( double d )
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{
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return static_cast< UINT16 >( d + 0.5 );
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}
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};
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} // namespace gil
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} // namespace boost
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#endif
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