Buffer passed to the LZW decoder to write decoded data. More...

Public Member Functions
	output_buffer (const palette_type &p, const image_descriptor &id, int transparent_color_index, image &output)
	Constructor.
void	write (unsigned int code)
	Write a data.
Private Attributes
const palette_type &	m_palette
	The palette from whick we take the colors of the image.
const image_descriptor &	m_id
	The image descriptor of the frame.
const int	m_transparent_color_index
	The index of the transparent color. -1 if none.
image &	m_output
	The image in which we save the decoded data.
std::size_t	m_x
	The x-position of the next pixel in the image.
std::size_t	m_y
	The y-position of the next pixel in the image.
int	m_interlace_pass
	Current pass in an interlaced image [0-3].
int	m_interlace_step
	Increment in the current pass of an interlaced image.

Detailed Description

Buffer passed to the LZW decoder to write decoded data.

Definition at line 359 of file gif.hpp.

Constructor & Destructor Documentation

claw::graphic::gif::reader::output_buffer::output_buffer	(	const palette_type &	p,
		const image_descriptor &	id,
		int	transparent_color_index,
		image &	output
	)

Constructor.

Parameters:

p	The palette from which we take the color.
id	The descriptor of the frame.
transparent_color_index	The index of the transparent color in p.
output	The image in which we store the data.

Definition at line 212 of file gif_reader.cpp.

  : m_palette(p), m_id(id), m_transparent_color_index(transparent_color_index),
    m_output(output), m_x(0), m_y(0), m_interlace_pass(0),
    m_interlace_step(8)
{

} // gif::reader::output_buffer::output_buffer()

Member Function Documentation

void claw::graphic::gif::reader::output_buffer::write ( unsigned int code )

Write a data.

Parameters:

code	The data to write.

Definition at line 226 of file gif_reader.cpp.

{
  assert(code < m_palette.size());
  assert(m_x < m_id.width);
  assert(m_y < m_id.height);

  m_output[m_y + m_id.top][m_x + m_id.left] = m_palette[code];

  if ( m_transparent_color_index != -1 )
    if ( code == (unsigned int)m_transparent_color_index )
      m_output[m_y + m_id.top][m_x + m_id.left].components.alpha = 0;

  ++m_x;

  if (m_x == m_id.width)
    {
      m_x = 0;

      if ( !m_id.is_interlaced() )
        ++m_y;
      else
        {
          m_y += m_interlace_step;

          while ( (m_y >= m_id.height) && (m_interlace_pass!=3) )
            {
              ++m_interlace_pass;
              switch (m_interlace_pass)
                {
                case 1: m_y = 4; m_interlace_step = 8; break;
                case 2: m_y = 2; m_interlace_step = 4; break;
                case 3: m_y = 1; m_interlace_step = 2; break;
                }
            }
        }
    }
} // gif::reader::output_buffer::write()