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//
// Copyright 2008 Christian Henning
//
// Distributed under 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_SCANLINE_READ_HPP
#define BOOST_GIL_EXTENSION_IO_BMP_DETAIL_SCANLINE_READ_HPP
#include <boost/gil/extension/io/bmp/detail/is_allowed.hpp>
#include <boost/gil/extension/io/bmp/detail/reader_backend.hpp>
#include <boost/gil/io/base.hpp>
#include <boost/gil/io/bit_operations.hpp>
#include <boost/gil/io/conversion_policies.hpp>
#include <boost/gil/io/device.hpp>
#include <boost/gil/io/reader_base.hpp>
#include <boost/gil/io/row_buffer_helper.hpp>
#include <boost/gil/io/scanline_read_iterator.hpp>
#include <boost/gil/io/typedefs.hpp>
#include <functional>
#include <type_traits>
#include <vector>
namespace boost { namespace gil {
///
/// BMP Scanline Reader
///
template< typename Device >
class scanline_reader< Device
, bmp_tag
>
: public reader_backend< Device
, bmp_tag
>
{
public:
using tag_t = bmp_tag;
using backend_t = reader_backend<Device, tag_t>;
using this_t = scanline_reader<Device, tag_t>;
using iterator_t = scanline_read_iterator<this_t>;
public:
//
// Constructor
//
scanline_reader( Device& device
, const image_read_settings< bmp_tag >& settings
)
: backend_t( device
, settings
)
, _pitch( 0 )
{
initialize();
}
/// Read part of image defined by View and return the data.
void read( byte_t* dst, int pos )
{
// jump to scanline
long offset = 0;
if( this->_info._height > 0 )
{
// the image is upside down
offset = this->_info._offset
+ ( this->_info._height - 1 - pos ) * this->_pitch;
}
else
{
offset = this->_info._offset
+ pos * _pitch;
}
this->_io_dev.seek( offset );
// read data
_read_function(this, dst);
}
/// Skip over a scanline.
void skip( byte_t*, int )
{
// nothing to do.
}
iterator_t begin() { return iterator_t( *this ); }
iterator_t end() { return iterator_t( *this, this->_info._height ); }
private:
void initialize()
{
if( this->_info._bits_per_pixel < 8 )
{
_pitch = (( this->_info._width * this->_info._bits_per_pixel ) + 7 ) >> 3;
}
else
{
_pitch = this->_info._width * (( this->_info._bits_per_pixel + 7 ) >> 3);
}
_pitch = (_pitch + 3) & ~3;
//
switch( this->_info._bits_per_pixel )
{
case 1:
{
this->_scanline_length = ( this->_info._width * num_channels< rgba8_view_t >::value + 3 ) & ~3;
read_palette();
_buffer.resize( _pitch );
_read_function = std::mem_fn(&this_t::read_1_bit_row);
break;
}
case 4:
{
switch( this->_info._compression )
{
case bmp_compression::_rle4:
{
io_error( "Cannot read run-length encoded images in iterator mode. Try to read as whole image." );
break;
}
case bmp_compression::_rgb :
{
this->_scanline_length = ( this->_info._width * num_channels< rgba8_view_t >::value + 3 ) & ~3;
read_palette();
_buffer.resize( _pitch );
_read_function = std::mem_fn(&this_t::read_4_bits_row);
break;
}
default:
{
io_error( "Unsupported compression mode in BMP file." );
}
}
break;
}
case 8:
{
switch( this->_info._compression )
{
case bmp_compression::_rle8:
{
io_error( "Cannot read run-length encoded images in iterator mode. Try to read as whole image." );
break;
}
case bmp_compression::_rgb:
{
this->_scanline_length = ( this->_info._width * num_channels< rgba8_view_t >::value + 3 ) & ~3;
read_palette();
_buffer.resize( _pitch );
_read_function = std::mem_fn(&this_t::read_8_bits_row);
break;
}
default: { io_error( "Unsupported compression mode in BMP file." ); break; }
}
break;
}
case 15:
case 16:
{
this->_scanline_length = ( this->_info._width * num_channels< rgb8_view_t >::value + 3 ) & ~3;
_buffer.resize( _pitch );
if( this->_info._compression == bmp_compression::_bitfield )
{
this->_mask.red.mask = this->_io_dev.read_uint32();
this->_mask.green.mask = this->_io_dev.read_uint32();
this->_mask.blue.mask = this->_io_dev.read_uint32();
this->_mask.red.width = detail::count_ones( this->_mask.red.mask );
this->_mask.green.width = detail::count_ones( this->_mask.green.mask );
this->_mask.blue.width = detail::count_ones( this->_mask.blue.mask );
this->_mask.red.shift = detail::trailing_zeros( this->_mask.red.mask );
this->_mask.green.shift = detail::trailing_zeros( this->_mask.green.mask );
this->_mask.blue.shift = detail::trailing_zeros( this->_mask.blue.mask );
}
else if( this->_info._compression == bmp_compression::_rgb )
{
switch( this->_info._bits_per_pixel )
{
case 15:
case 16:
{
this->_mask.red.mask = 0x007C00; this->_mask.red.width = 5; this->_mask.red.shift = 10;
this->_mask.green.mask = 0x0003E0; this->_mask.green.width = 5; this->_mask.green.shift = 5;
this->_mask.blue.mask = 0x00001F; this->_mask.blue.width = 5; this->_mask.blue.shift = 0;
break;
}
case 24:
case 32:
{
this->_mask.red.mask = 0xFF0000; this->_mask.red.width = 8; this->_mask.red.shift = 16;
this->_mask.green.mask = 0x00FF00; this->_mask.green.width = 8; this->_mask.green.shift = 8;
this->_mask.blue.mask = 0x0000FF; this->_mask.blue.width = 8; this->_mask.blue.shift = 0;
break;
}
}
}
else
{
io_error( "Unsupported BMP compression." );
}
_read_function = std::mem_fn(&this_t::read_15_bits_row);
break;
}
case 24:
{
this->_scanline_length = ( this->_info._width * num_channels< rgb8_view_t >::value + 3 ) & ~3;
_read_function = std::mem_fn(&this_t::read_row);
break;
}
case 32:
{
this->_scanline_length = ( this->_info._width * num_channels< rgba8_view_t >::value + 3 ) & ~3;
_read_function = std::mem_fn(&this_t::read_row);
break;
}
default:
{
io_error( "Unsupported bits per pixel." );
}
}
}
void read_palette()
{
if( this->_palette.size() > 0 )
{
// palette has been read already.
return;
}
int entries = this->_info._num_colors;
if( entries == 0 )
{
entries = 1u << this->_info._bits_per_pixel;
}
this->_palette.resize( entries, rgba8_pixel_t(0,0,0,0) );
for( int i = 0; i < entries; ++i )
{
get_color( this->_palette[i], blue_t() ) = this->_io_dev.read_uint8();
get_color( this->_palette[i], green_t() ) = this->_io_dev.read_uint8();
get_color( this->_palette[i], red_t() ) = this->_io_dev.read_uint8();
// there are 4 entries when windows header
// but 3 for os2 header
if( this->_info._header_size == bmp_header_size::_win32_info_size )
{
this->_io_dev.read_uint8();
}
} // for
}
template< typename View >
void read_bit_row( byte_t* dst )
{
using src_view_t = View;
using dst_view_t = rgba8_image_t::view_t;
src_view_t src_view = interleaved_view( this->_info._width
, 1
, (typename src_view_t::x_iterator) &_buffer.front()
, this->_pitch
);
dst_view_t dst_view = interleaved_view( this->_info._width
, 1
, (typename dst_view_t::value_type*) dst
, num_channels< dst_view_t >::value * this->_info._width
);
typename src_view_t::x_iterator src_it = src_view.row_begin( 0 );
typename dst_view_t::x_iterator dst_it = dst_view.row_begin( 0 );
for( dst_view_t::x_coord_t i = 0
; i < this->_info._width
; ++i, src_it++, dst_it++
)
{
unsigned char c = get_color( *src_it, gray_color_t() );
*dst_it = this->_palette[c];
}
}
// Read 1 bit image. The colors are encoded by an index.
void read_1_bit_row( byte_t* dst )
{
this->_io_dev.read( &_buffer.front(), _pitch );
_mirror_bits( _buffer );
read_bit_row< gray1_image_t::view_t >( dst );
}
// Read 4 bits image. The colors are encoded by an index.
void read_4_bits_row( byte_t* dst )
{
this->_io_dev.read( &_buffer.front(), _pitch );
_swap_half_bytes( _buffer );
read_bit_row< gray4_image_t::view_t >( dst );
}
/// Read 8 bits image. The colors are encoded by an index.
void read_8_bits_row( byte_t* dst )
{
this->_io_dev.read( &_buffer.front(), _pitch );
read_bit_row< gray8_image_t::view_t >( dst );
}
/// Read 15 or 16 bits image.
void read_15_bits_row( byte_t* dst )
{
using dst_view_t = rgb8_view_t;
dst_view_t dst_view = interleaved_view( this->_info._width
, 1
, (typename dst_view_t::value_type*) dst
, this->_pitch
);
typename dst_view_t::x_iterator dst_it = dst_view.row_begin( 0 );
//
byte_t* src = &_buffer.front();
this->_io_dev.read( src, _pitch );
for( dst_view_t::x_coord_t i = 0
; i < this->_info._width
; ++i, src += 2
)
{
int p = ( src[1] << 8 ) | src[0];
int r = ((p & this->_mask.red.mask) >> this->_mask.red.shift) << (8 - this->_mask.red.width);
int g = ((p & this->_mask.green.mask) >> this->_mask.green.shift) << (8 - this->_mask.green.width);
int b = ((p & this->_mask.blue.mask) >> this->_mask.blue.shift) << (8 - this->_mask.blue.width);
get_color( dst_it[i], red_t() ) = static_cast< byte_t >( r );
get_color( dst_it[i], green_t() ) = static_cast< byte_t >( g );
get_color( dst_it[i], blue_t() ) = static_cast< byte_t >( b );
}
}
void read_row( byte_t* dst )
{
this->_io_dev.read( dst, _pitch );
}
private:
// the row pitch must be multiple of 4 bytes
int _pitch;
std::vector<byte_t> _buffer;
detail::mirror_bits <std::vector<byte_t>, std::true_type> _mirror_bits;
detail::swap_half_bytes<std::vector<byte_t>, std::true_type> _swap_half_bytes;
std::function<void(this_t*, byte_t*)> _read_function;
};
} // namespace gil
} // namespace boost
#endif
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