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/*
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_PNM_DETAIL_SCANLINE_READ_HPP
#define BOOST_GIL_EXTENSION_IO_PNM_DETAIL_SCANLINE_READ_HPP
////////////////////////////////////////////////////////////////////////////////////////
/// \file
/// \brief
/// \author Christian Henning \n
///
/// \date 2012 \n
///
////////////////////////////////////////////////////////////////////////////////////////
#include <vector>
#include <boost/bind.hpp>
#include <boost/function.hpp>
#include <boost/gil.hpp>
#include <boost/gil/io/base.hpp>
#include <boost/gil/io/conversion_policies.hpp>
#include <boost/gil/io/row_buffer_helper.hpp>
#include <boost/gil/io/bit_operations.hpp>
#include <boost/gil/io/reader_base.hpp>
#include <boost/gil/io/device.hpp>
#include <boost/gil/io/scanline_read_iterator.hpp>
#include <boost/gil/io/typedefs.hpp>
#include <boost/gil/extension/io/pnm/detail/reader_backend.hpp>
#include <boost/gil/extension/io/pnm/detail/is_allowed.hpp>
namespace boost { namespace gil {
///
/// PNM Reader
///
template< typename Device >
class scanline_reader< Device
, pnm_tag
>
: public reader_backend< Device
, pnm_tag
>
{
public:
typedef pnm_tag tag_t;
typedef reader_backend < Device, tag_t > backend_t;
typedef scanline_reader< Device, tag_t > this_t;
typedef scanline_read_iterator< this_t > iterator_t;
public:
scanline_reader( Device& device
, const image_read_settings< pnm_tag >& settings
)
: backend_t( device
, settings
)
{
initialize();
}
/// Read part of image defined by View and return the data.
void read( byte_t* dst
, int
)
{
_read_function( this, dst );
}
/// Skip over a scanline.
void skip( byte_t*, int )
{
_skip_function( this );
}
iterator_t begin() { return iterator_t( *this ); }
iterator_t end() { return iterator_t( *this, this->_info._height ); }
private:
void initialize()
{
switch( this->_info._type )
{
// reading mono text is reading grayscale but with only two values
case pnm_image_type::mono_asc_t::value:
case pnm_image_type::gray_asc_t::value:
{
this->_scanline_length = this->_info._width;
_read_function = boost::mem_fn( &this_t::read_text_row );
_skip_function = boost::mem_fn( &this_t::skip_text_row );
break;
}
case pnm_image_type::color_asc_t::value:
{
this->_scanline_length = this->_info._width * num_channels< rgb8_view_t >::value;
_read_function = boost::mem_fn( &this_t::read_text_row );
_skip_function = boost::mem_fn( &this_t::skip_text_row );
break;
}
case pnm_image_type::mono_bin_t::value:
{
//gray1_image_t
this->_scanline_length = ( this->_info._width + 7 ) >> 3;
_read_function = boost::mem_fn( &this_t::read_binary_bit_row );
_skip_function = boost::mem_fn( &this_t::skip_binary_row );
break;
}
case pnm_image_type::gray_bin_t::value:
{
// gray8_image_t
this->_scanline_length = this->_info._width;
_read_function = boost::mem_fn( &this_t::read_binary_byte_row );
_skip_function = boost::mem_fn( &this_t::skip_binary_row );
break;
}
case pnm_image_type::color_bin_t::value:
{
// rgb8_image_t
this->_scanline_length = this->_info._width * num_channels< rgb8_view_t >::value;
_read_function = boost::mem_fn( &this_t::read_binary_byte_row );
_skip_function = boost::mem_fn( &this_t::skip_binary_row );
break;
}
default: { io_error( "Unsupported pnm file." ); break; }
}
}
void read_text_row( byte_t* dst )
{
for( std::size_t x = 0; x < this->_scanline_length; ++x )
{
for( uint32_t k = 0; ; )
{
int ch = this->_io_dev.getc_unchecked();
if( isdigit( ch ))
{
_text_buffer[ k++ ] = static_cast< char >( ch );
}
else if( k )
{
_text_buffer[ k ] = 0;
break;
}
else if( ch == EOF || !isspace( ch ))
{
return;
}
}
int value = atoi( _text_buffer );
if( this->_info._max_value == 1 )
{
// for pnm format 0 is white
dst[x] = ( value != 0 )
? 0
: 255;
}
else
{
dst[x] = static_cast< byte_t >( value );
}
}
}
void skip_text_row()
{
for( std::size_t x = 0; x < this->_scanline_length; ++x )
{
for( uint32_t k = 0; ; )
{
int ch = this->_io_dev.getc_unchecked();
if( isdigit( ch ))
{
k++;
}
else if( k )
{
break;
}
else if( ch == EOF || !isspace( ch ))
{
return;
}
}
}
}
void read_binary_bit_row( byte_t* dst )
{
this->_io_dev.read( dst
, this->_scanline_length
);
_negate_bits ( dst, this->_scanline_length );
_swap_half_bytes( dst, this->_scanline_length );
}
void read_binary_byte_row( byte_t* dst )
{
this->_io_dev.read( dst
, this->_scanline_length
);
}
void skip_binary_row()
{
this->_io_dev.seek( static_cast<long>( this->_scanline_length ), SEEK_CUR );
}
private:
char _text_buffer[16];
// For bit_aligned images we need to negate all bytes in the row_buffer
// to make sure that 0 is black and 255 is white.
detail::negate_bits < std::vector< byte_t >, mpl::true_ > _negate_bits;
detail::swap_half_bytes< std::vector< byte_t >, mpl::true_ > _swap_half_bytes;
boost::function< void ( this_t*, byte_t* ) > _read_function;
boost::function< void ( this_t* ) > _skip_function;
};
} // namespace gil
} // namespace boost
#endif
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