63e88f80
 Hu Chunming
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//
// Copyright 2007-2008 Christian Henning, Andreas Pokorny
//
// 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_IO_IO_HPP
#define BOOST_GIL_IO_IO_HPP
/*!
* \page iobackend Adding a new io backend
* \section Overview of backend requirements
* To add support for a new IO backend the following is required:
* - a format tag, to identify the image format, derived from boost::gil::format_tag
* - boolean meta function is_supported<PixelType,FormatTag> must be implemented for
* the new format tag
* - explicit specialisation of image_read_info<FormatTag> must be provided, containing
* runtime information available before/at reading the image
* - explicit specialisation of image_write_info<FormatTag> must be provided, containing
* runtime encoding parameters for writing an image
* - An image reader must be specialized:
* \code
* template<typename IODevice, typename ConversionPolicy>
* struct boost::gil::reader<IODevice,FormatTag,ConversionPolicy>
* {
* reader( IODevice & device )
* reader( IODevice & device, typename ConversionPolicy::color_converter_type const& cc )
* image_read_info<FormatTag> get_info();
* template<typename Image>
* void read_image( Image &, point_t const& top_left );
* template<typename View>
* void read_view( View &, point_t const& top_left );
* };
* \endcode
* - An image writer must be specialized:
* \code
* \template <typename IODevice>
* struct boost::gil::writer<IODevice,FormatTag>
* {
* writer( IODevice & device )
* template<typename View>
* void apply( View const&, point_t const& top_left );
* template<typename View>
* void apply( View const&, point_t const& top_left, image_write_info<FormatTag> const& );
* };
* \endcode
*
* Or instead of the items above implement overloads of read_view, read_and_convert_view, read_image,
* read_and_convert_image, write_view and read_image_info.
*
* \section ConversionPolicy Interface of the ConversionPolicy
* There are two different conversion policies in use, when reading images:
* read_and_convert<ColorConverter> and read_and_no_convert. ColorConverter
* can be a user defined color converter.
*
* \code
* struct ConversionPolicy
* {
* template<typename InputIterator,typename OutputIterator>
* void read( InputIterator in_begin, InputIterator in_end,
* OutputIterator out_end );
* };
* \endcode
*
* Methods like read_view and read_image are supposed to bail out with an
* exception instead of converting the image
*
* \section IODevice Concept of IO Device
* A Device is simply an object used to read and write data to and from a stream.
* The IODevice was added as a template paramter to be able to replace the file_name
* access functionality. This is only an interim solution, as soon as boost provides
* a good IO library, interfaces/constraints provided by that library could be used.
*
* \code
* concept IODevice
* {
* void IODevice::read( unsigned char* data, int count );
* void IODevice::write( unsigned char* data, int count );
* void IODevice::seek(long count, int whence);
* void IODevice::flush();
* };
* \endcode
*
* For the time being a boolean meta function must be specialized:
* \code
* namespace boost{namespace gil{namespace detail{
* template<typename Device>
* struct detail::is_input_device;
* }}}
* \endcode
*
*/
#endif
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