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 bet-
       ter 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 com-
       bines 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.

                                                                     libpgm(3)