//
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// Copyright 2012 Kenneth Riddile, Christian Henning
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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_TARGA_DETAIL_SCANLINE_READ_HPP
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#define BOOST_GIL_EXTENSION_IO_TARGA_DETAIL_SCANLINE_READ_HPP
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#include <boost/gil/extension/io/targa/detail/is_allowed.hpp>
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#include <boost/gil/extension/io/targa/detail/reader_backend.hpp>
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#include <boost/gil/io/base.hpp>
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#include <boost/gil/io/bit_operations.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/row_buffer_helper.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 <vector>
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namespace boost { namespace gil {
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///
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/// Targa 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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, targa_tag
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>
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: public reader_backend< Device
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, targa_tag
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>
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{
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public:
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using tag_t = targa_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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//
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// Constructor
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//
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scanline_reader( Device& device
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, const image_read_settings< targa_tag >& settings
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)
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: backend_t( 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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/// Read part of image defined by View and return the data.
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void read( byte_t* dst, int pos )
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{
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// jump to scanline
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long offset = this->_info._offset
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+ ( this->_info._height - 1 - pos ) * static_cast< long >( this->_scanline_length );
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this->_io_dev.seek( offset );
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read_row( dst );
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}
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/// Skip over a scanline.
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void skip( byte_t*, int )
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{
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this->_io_dev.seek( static_cast<long>( this->_scanline_length )
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, SEEK_CUR
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);
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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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if( this->_info._color_map_type != targa_color_map_type::_rgb )
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{
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io_error( "scanline reader cannot read indexed targa files." );
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}
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if( this->_info._image_type != targa_image_type::_rgb )
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{
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io_error( "scanline reader cannot read this targa image type." );
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}
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switch( this->_info._image_type )
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{
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case targa_image_type::_rgb:
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{
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if( this->_info._color_map_type != targa_color_map_type::_rgb )
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{
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io_error( "Inconsistent color map type and image type in targa file." );
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}
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if( this->_info._color_map_length != 0 )
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{
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io_error( "Non-indexed targa files containing a palette are not supported." );
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}
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if( this->_info._screen_origin_bit )
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{
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io_error( "scanline reader cannot read targa files which have screen origin bit set." );
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}
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switch( this->_info._bits_per_pixel )
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{
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case 24:
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case 32:
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{
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this->_scanline_length = this->_info._width * ( this->_info._bits_per_pixel / 8 );
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// jump to first scanline
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this->_io_dev.seek( static_cast< long >( this->_info._offset ));
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break;
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}
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default:
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{
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io_error( "Unsupported bit depth in targa file." );
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break;
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}
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}
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break;
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}
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default:
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{
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io_error( "Unsupported image type in targa file." );
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break;
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}
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}
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}
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void read_row( byte_t* dst )
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{
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this->_io_dev.read( dst, this->_scanline_length );
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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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