This class read data from a jpeg file and store it in an image. More...

#include <jpeg.hpp>

Classes
class	grayscale_to_pixel32
	Functor converting a grey level pixel to a ARGB pixel. More...
class	RGB_to_pixel32
	Functor converting a RGB pixel to a ARGB pixel. More...
struct	source_manager
	Source manager that allow us to read from a std::istream. More...
Public Member Functions
	reader (image &img)
	Constructor.
	reader (image &img, std::istream &f)
	Constructor. Load an image from a jpeg file.
void	load (std::istream &f)
	Load an image from a jpeg file.
Private Member Functions
template<class Convert >
void	read_data (jpeg_decompress_struct &cinfo, const Convert &pixel_convert)
	Decompress a RGB jpeg image.
void	read_from_file (std::istream &f)
	Load an image from a jpeg file.
void	decompress (std::istream &f, jpeg_decompress_struct &cinfo)
	Decompress the data of a Jpeg file.
void	create_decompress_info (jpeg_decompress_struct &cinfo, source_manager &infile) const
	Initialize the jpeg decompression structure.
Private Attributes
image &	m_image
	The image in which we store the data we read.

Detailed Description

This class read data from a jpeg file and store it in an image.

Author:: Julien Jorge

Definition at line 79 of file jpeg.hpp.

Constructor & Destructor Documentation

claw::graphic::jpeg::reader::reader ( image & img )

Constructor.

Parameters:

img	The image in which the data will be stored.

Definition at line 218 of file jpeg_reader.cpp.

  : m_image( img )
{

} // jpeg::reader::reader()

claw::graphic::jpeg::reader::reader	(	image &	img,
		std::istream &	f
	)

Constructor. Load an image from a jpeg file.

Parameters:

img	The image in which the data will be stored.
f	The file from which we read the data.

Postcondition:: img contains the data from f.

Definition at line 231 of file jpeg_reader.cpp.

References load().

  : m_image( img )
{
  load(f);
} // jpeg::reader::reader()

Member Function Documentation

void claw::graphic::jpeg::reader::create_decompress_info	(	jpeg_decompress_struct &	cinfo,
		source_manager &	infile
	)		const `[private]`

Initialize the jpeg decompression structure.

Parameters:

cinfo	The structure to initialize.
infile	The source manager.

Definition at line 344 of file jpeg_reader.cpp.

References claw__graphic__jpeg__source_manager__fill_input_buffer(), claw__graphic__jpeg__source_manager__init_source(), claw__graphic__jpeg__source_manager__skip_input_data(), claw__graphic__jpeg__source_manager__term_source(), and claw::graphic::jpeg::reader::source_manager::pub.

{
  jpeg_create_decompress(&cinfo);

  cinfo.src = &infile.pub;
  cinfo.client_data = &infile;

  infile.pub.fill_input_buffer =
    claw__graphic__jpeg__source_manager__fill_input_buffer;
  infile.pub.skip_input_data =
    claw__graphic__jpeg__source_manager__skip_input_data;
  infile.pub.init_source = claw__graphic__jpeg__source_manager__init_source;
  infile.pub.resync_to_restart = jpeg_resync_to_restart;
  infile.pub.term_source = claw__graphic__jpeg__source_manager__term_source;
} // jpeg::reader::create_decompress_info()

void claw::graphic::jpeg::reader::decompress	(	std::istream &	f,
		jpeg_decompress_struct &	cinfo
	)		`[private]`

Decompress the data of a Jpeg file.

Parameters:

f	Jpeg file.
cinfo	Info on the decompression process (libjpeg concerned).

Definition at line 298 of file jpeg_reader.cpp.

References CLAW_EXCEPTION, claw::graphic::jpeg::error_manager::error_string, claw::graphic::jpeg__error_manager__error_exit(), claw::graphic::jpeg::error_manager::pub, and claw::graphic::jpeg::error_manager::setjmp_buffer.

{
  error_manager jerr;
  jpeg_error_mgr* jerr_saved = cinfo.err;

  cinfo.err = jpeg_std_error(&jerr.pub);
  jerr.pub.error_exit = jpeg__error_manager__error_exit;

  if ( setjmp(jerr.setjmp_buffer) )
    {
      jpeg_abort_decompress(&cinfo);
      throw CLAW_EXCEPTION(jerr.error_string);
    }

  jpeg_read_header(&cinfo, TRUE);
  jpeg_start_decompress( &cinfo );

  try
    {
      m_image.set_size( cinfo.image_width, cinfo.image_height );

      if ( cinfo.out_color_components == 3 )
        read_data( cinfo, RGB_to_pixel32() );
      else if ( cinfo.out_color_components == 1 )
        read_data( cinfo, grayscale_to_pixel32() );
      else
        throw CLAW_EXCEPTION( "invalid number of colors per channel" );

      jpeg_finish_decompress(&cinfo);
    }
  catch(...)
    {
      jpeg_abort_decompress(&cinfo);
      throw;
    }

  cinfo.err = jerr_saved;
} // jpeg::reader::decompress()

void claw::graphic::jpeg::reader::load ( std::istream & f )

Load an image from a jpeg file.

Parameters:

f	JPEG file.

Definition at line 242 of file jpeg_reader.cpp.

References CLAW_PRECOND.

Referenced by reader().

{
  CLAW_PRECOND( !!f );

  std::istream::pos_type init_pos = f.tellg();

  try
    {
      read_from_file(f);
    }
  catch(...)
    {
      f.clear();
      f.seekg( init_pos, std::ios_base::beg );
      throw;
    }
} // jpeg::reader::load()

template<class Convert >

void claw::graphic::jpeg::reader::read_data	(	jpeg_decompress_struct &	cinfo,
		const Convert &	pixel_convert
	)		`[private]`

Decompress a RGB jpeg image.

Parameters:

cinfo	Informations about the decompression process.
pixel_convert	Operator to use to convert pixels from input.

Definition at line 42 of file jpeg_reader.tpp.

References CLAW_EXCEPTION, claw::graphic::jpeg::error_manager::error_string, claw::graphic::jpeg__error_manager__error_exit(), claw::graphic::jpeg::error_manager::pub, and claw::graphic::jpeg::error_manager::setjmp_buffer.

{
  const unsigned int pixel_size = cinfo.output_components;
  JSAMPLE* buffer = new JSAMPLE[cinfo.output_width * pixel_size];

  error_manager jerr;
  jpeg_error_mgr* jerr_saved = cinfo.err;

  cinfo.err = jpeg_std_error(&jerr.pub);
  jerr.pub.error_exit = jpeg__error_manager__error_exit;

  if ( setjmp(jerr.setjmp_buffer) )
    {
      delete[] buffer;
      throw CLAW_EXCEPTION(jerr.error_string);
    }

  while (cinfo.output_scanline < cinfo.output_height)
    {
      jpeg_read_scanlines(&cinfo, &buffer, 1);

      scanline::iterator pixel = m_image[cinfo.output_scanline-1].begin();

      for ( unsigned int i=0; i!=pixel_size*m_image.width();
            i+=pixel_size, ++pixel )
        *pixel = pixel_convert( &buffer[i] );
    }

  delete[] buffer;
  cinfo.err = jerr_saved;
} // jpeg::reader::read_data()

void claw::graphic::jpeg::reader::read_from_file ( std::istream & f ) [private]

Load an image from a jpeg file.

Parameters:

f	Jpeg file.

Definition at line 265 of file jpeg_reader.cpp.

References CLAW_EXCEPTION, claw::graphic::jpeg::error_manager::error_string, claw::graphic::jpeg__error_manager__error_exit(), claw::graphic::jpeg::error_manager::pub, and claw::graphic::jpeg::error_manager::setjmp_buffer.

{
  source_manager infile(f);
  jpeg_decompress_struct cinfo;
  error_manager jerr;

  cinfo.err = jpeg_std_error(&jerr.pub);
  
  if ( setjmp(jerr.setjmp_buffer) )
    throw CLAW_EXCEPTION(jerr.error_string);

  create_decompress_info( cinfo, infile );
  jerr.pub.error_exit = jpeg__error_manager__error_exit;
  
  try
    {
      decompress(f, cinfo);
      jpeg_destroy_decompress(&cinfo);
    }
  catch(...)
    {
      jpeg_destroy_decompress(&cinfo);
      throw;
    }
} // jpeg::reader::read_from_file()

Member Data Documentation

image& claw::graphic::jpeg::reader::m_image [private]

The image in which we store the data we read.

Definition at line 158 of file jpeg.hpp.

The documentation for this class was generated from the following files:

claw::graphic::jpeg::reader Class Reference

Classes

Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation