claw::rle_encoder< OutputBuffer > Class Template Reference

A class to help run-length encoding (RLE) streams. More...

#include <rle_encoder.hpp>

List of all members.

Public Types
typedef OutputBuffer	output_buffer_type
	The type of the output buffer.
typedef output_buffer_type::pattern_type	pattern_type
	The type of the stored data.
Public Member Functions
template<typename Iterator >
void	encode (Iterator first, Iterator last, output_buffer_type &output) const
	Encode a range of datas.
Private Types
typedef std::list< pattern_type >	raw_buffer_type
	The type of the buffer on which we store the raw data.

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Detailed Description

template<typename OutputBuffer>
class claw::rle_encoder< OutputBuffer >

A class to help run-length encoding (RLE) streams.

Template parameters :

• OutputBuffer The type of the output buffer.

The OutputBuffer type must have the following typedefs :

• pattern_type, the type of the stored data.

The OutputBuffer type must have the following methods :

• encode( unsigned int n, pattern_type pattern ), code n times the pattern ;
• template<typename Iterator> raw( Iterator first, Iterator last ) ;
• unsigned int min_interesting() returns the minimum number of time we must have the same value before compressing it ;
• unsigned int max_encodable() return the maximum number of time we can have the same value before compressing it.

Author:

Julien Jorge

Definition at line 58 of file rle_encoder.hpp.

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Member Typedef Documentation

template<typename OutputBuffer>

typedef OutputBuffer claw::rle_encoder< OutputBuffer >::output_buffer_type

The type of the output buffer.

Reimplemented in claw::graphic::targa::writer::rle_targa_encoder< Pixel >.

Definition at line 62 of file rle_encoder.hpp.

template<typename OutputBuffer>

typedef output_buffer_type::pattern_type claw::rle_encoder< OutputBuffer >::pattern_type

The type of the stored data.

Definition at line 65 of file rle_encoder.hpp.

template<typename OutputBuffer>

typedef std::list<pattern_type> claw::rle_encoder< OutputBuffer >::raw_buffer_type [private]

The type of the buffer on which we store the raw data.

Definition at line 69 of file rle_encoder.hpp.

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Member Function Documentation

template<typename OutputBuffer >

template<typename Iterator >

void claw::rle_encoder< OutputBuffer >::encode	(	Iterator	first,
		Iterator	last,
		output_buffer_type &	output
	)			const

Encode a range of datas.

Parameters:

	first	Iterator on the first data.
	last	Iterator past the last data.
	output	The buffer on which we write the compressed data.

Precondition:

Iterator::value_type must be castable to pattern_type.

Definition at line 43 of file rle_encoder.tpp.

Referenced by claw::graphic::targa::writer::save_rle_true_color(), and claw::graphic::pcx::writer::save_rle_true_color().

{
  const unsigned int max_encodable = output.max_encodable();
  const unsigned int min_interesting = output.min_interesting();
  raw_buffer_type raw_buffer;

  assert( max_encodable > 0 );

  while (first != last)
    {
      unsigned int count = 1;
      pattern_type pattern = *first;
      Iterator saved_it = first;
      ++first;
      bool ok = true;

      // try to find enough similar data
      while ( ok && (first != last) && (count < max_encodable) )
        if (*first == pattern)
          {
            ++count;
            ++first;
          }
        else
          ok = false;

      // if we have enough data
      if ( count >= min_interesting )
        {
          if ( !raw_buffer.empty() )
            {
              output.raw( raw_buffer.begin(), raw_buffer.end() );
              raw_buffer.clear();
            }

          output.encode( count, pattern );
        }
      else
        raw_buffer.insert( raw_buffer.end(), saved_it, first );
    }

  
  if ( !raw_buffer.empty() )
    output.raw( raw_buffer.begin(), raw_buffer.end() );
} // rle_encoder::encode()

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

• rle_encoder.hpp
• impl/rle_encoder.tpp