libpgm(3)

NAME
     libpgm - functions to support portable graymap programs

SYNOPSIS
     #include <pgm.h>
     cc ... libpgm.a libpbm.a


DESCRIPTION
   TYPES AND CONSTANTS
     typedef ... gray;
     #define PGM_MAXMAXVAL ...
     extern gray pgm_pbmmaxval;

     Each gray should contain only the values between 0 and PGM_MAXMAXVAL.
     pgm_pbmmaxval is the maxval used when a PGM program reads a PBM file.
     Normally it is 1; however, for some programs, a larger value gives better
     results.

     #define PGM_FORMAT ...
     #define RPGM_FORMAT ...
     #define PGM_TYPE PGM_FORMAT
     int PGM_FORMAT_TYPE( int format )

     For distinguishing different file formats and types.

   INITIALIZATION
     void pgm_init( int* argcP, char* argv[] )

     All PGM programs must call this routine.

   MEMORY MANAGEMENT
     gray** pgm_allocarray( int cols, int rows )

     Allocate an array of grays.

     gray* pgm_allocrow( int cols )

     Allocate a row of the given number of grays.

     void pgm_freearray( gray** grays, int rows )

     Free the array allocated with pgm_allocarray() containing the given
     number of rows.

     void pgm_freerow( gray* grayrow )

     Free a row of grays.

   READING FILES
     void pgm_readpgminit( FILE* fp, int* colsP, int* rowsP, gray* maxvalP, int* formatP )
     Read the header from a PGM file, filling in the rows, cols, maxval and
     format variables.

     void pgm_readpgmrow( FILE* fp, gray* grayrow, int cols, gray maxval, int format )

     Read a row of grays into the grayrow array.  Format, cols, and maxval
     were filled in by pgm_readpgminit().

     gray** pgm_readpgm( FILE* fp, int* colsP, int* rowsP, gray* maxvalP )

     Read an entire graymap file into memory, returning the allocated array
     and filling in the rows, cols and maxval variables.  This function
     combines pgm_readpgminit(), pgm_allocarray() and pgm_readpgmrow().

   WRITING FILES
     void pgm_writepgminit( FILE* fp, int cols, int rows, gray maxval, int forceplain )

     Write the header for a portable graymap file.  The forceplain flag forces
     a plain-format file to be written, as opposed to a raw-format one.

     void pgm_writepgmrow( FILE* fp, gray* grayrow, int cols, gray maxval, int forceplain )

     Write a row from a portable graymap.

     void pgm_writepgm( FILE* fp, gray** grays, int cols, int rows, gray maxval, int forceplain )

     Write the header and all data for a portable graymap.  This function
     combines pgm_writepgminit() and pgm_writepgmrow().

SEE ALSO
     libpbm(3), libppm(3), libpnm(3)

AUTHOR
     Copyright (C) 1989, 1991 by Tony Hansen and Jef Poskanzer.