//
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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_DETAIL_SCANLINE_READ_HPP
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#define BOOST_GIL_EXTENSION_IO_JPEG_DETAIL_SCANLINE_READ_HPP
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#include <boost/gil/extension/io/jpeg/detail/base.hpp>
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#include <boost/gil/extension/io/jpeg/detail/is_allowed.hpp>
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#include <boost/gil/extension/io/jpeg/detail/reader_backend.hpp>
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#include <boost/gil/io/base.hpp>
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#include <boost/gil/io/conversion_policies.hpp>
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#include <boost/gil/io/device.hpp>
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#include <boost/gil/io/reader_base.hpp>
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#include <boost/gil/io/scanline_read_iterator.hpp>
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#include <boost/gil/io/typedefs.hpp>
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#include <csetjmp>
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#include <vector>
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namespace boost { namespace gil {
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#if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
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#pragma warning(push)
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#pragma warning(disable:4611) //interaction between '_setjmp' and C++ object destruction is non-portable
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#endif
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///
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/// JPEG Scanline Reader
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///
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template< typename Device >
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class scanline_reader< Device
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, jpeg_tag
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>
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: public reader_backend< Device
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, jpeg_tag
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>
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{
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public:
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using tag_t = jpeg_tag;
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using backend_t = reader_backend<Device, tag_t>;
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using this_t = scanline_reader<Device, tag_t>;
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using iterator_t = scanline_read_iterator<this_t>;
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public:
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scanline_reader( Device& device
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, const image_read_settings< jpeg_tag >& settings
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)
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: reader_backend< Device
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, jpeg_tag
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>( device
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, settings
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)
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{
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initialize();
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}
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void read( byte_t* dst
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, int
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)
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{
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// Fire exception in case of error.
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if( setjmp( this->_mark )) { this->raise_error(); }
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// read data
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read_scanline( dst );
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}
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/// Skip over a scanline.
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void skip( byte_t* dst, int )
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{
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// Fire exception in case of error.
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if( setjmp( this->_mark )) { this->raise_error(); }
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// read data
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read_scanline( dst );
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}
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iterator_t begin() { return iterator_t( *this ); }
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iterator_t end() { return iterator_t( *this, this->_info._height ); }
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private:
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void initialize()
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{
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this->get()->dct_method = this->_settings._dct_method;
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io_error_if( jpeg_start_decompress( this->get() ) == false
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, "Cannot start decompression." );
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switch( this->_info._color_space )
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{
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case JCS_GRAYSCALE:
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{
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this->_scanline_length = this->_info._width;
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break;
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}
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case JCS_RGB:
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//!\todo add Y'CbCr? We loose image quality when reading JCS_YCbCr as JCS_RGB
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case JCS_YCbCr:
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{
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this->_scanline_length = this->_info._width * num_channels< rgb8_view_t >::value;
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break;
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}
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case JCS_CMYK:
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//!\todo add Y'CbCrK? We loose image quality when reading JCS_YCCK as JCS_CMYK
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case JCS_YCCK:
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{
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this->get()->out_color_space = JCS_CMYK;
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this->_scanline_length = this->_info._width * num_channels< cmyk8_view_t >::value;
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break;
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}
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default: { io_error( "Unsupported jpeg color space." ); }
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}
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}
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void read_scanline( byte_t* dst )
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{
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JSAMPLE *row_adr = reinterpret_cast< JSAMPLE* >( dst );
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// Read data.
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io_error_if( jpeg_read_scanlines( this->get()
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, &row_adr
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, 1
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) != 1
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, "jpeg_read_scanlines: fail to read JPEG file"
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);
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}
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};
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#if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
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#pragma warning(pop)
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#endif
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} // namespace gil
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} // namespace boost
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#endif
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