=head1	NAME

dkof - output filtering

=head1	SYNOPSIS

  #include <dkof.h>


  dk_stream_t *
  dkof_open (dk_stream_t *target, size_t nof);
  
  void
  dkof_close (dk_stream_t *str);
  
  int
  dkof_set (dk_stream_t *str, size_t n, int what);
  
  int
  dkof_start_chunk (dk_stream_t *str);
  
  int
  dkof_end_chunk (dk_stream_t *str);
  
  void
  dkof_set_crnl (dk_stream_t *str, int v);
  
=head1	DESCRIPTION

Some file formats - i.e. Postscript and PDF - mix plain text and compressed
chunks.

Output filters are intended to create the compressed chunks.

The dkof module creates a new I<dk_stream_t> for compression and encoding
which writes output to an existing I<dk_stream_t>.

The dkof_open() function creates such a new stream. The I<nof> parameter
is the number of filters to apply. The function returns a valid pointer
on success, NULL on error.

The dkof_set() function sets a filter cell I<n> to a
specified method I<what>. Filter cell I<n-1> is applied first,
0 is the last cell before writing the output.
The following filter cell types can be used:

=over	4

=item	* DK_OF_TYPE_FLATE

Flate compression from the zlib library.

=item	* ASCII85-encoding

ASCII-85-Encoding.

=item	* DK_OF_TYPE_BUFFERED

Output data is collected to write 512-byte buffers instead of single bytes.

=back


Each stream created by dkof_open() must be closed after usage by the
dkof_close() function.

The dkof_set_crnl() function can be used to set up UNIX style line
ends (I<v=0>) or Windows style line ends (I<v=1>).

Before writing a compressed chunk the stream must be initialized
using dkof_start_chunk().

After writing all chunk data the dkof_end_chunk() function must be used
to flush all buffers.

=head1	AUTHOR

Dirk Krause

=head1	COPYRIGHT AND LICENSE

Copyright (c) 2001-2008, Dirk Krause
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

 * Redistributions of source code must retain the above
   copyright notice, this list of conditions and the
   following disclaimer.

 * Redistributions in binary form must reproduce the above
   copyright notice, this list of conditions and the following
   disclaimer in the documentation and/or other materials
   provided with the distribution.

 * Neither the name of the Dirk Krause nor the names of
   contributors may be used to endorse or promote products
   derived from this software without specific prior written
   permission.

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