bionic (3) libpgm.3.gz

NAME

       libpgm - functions to support portable graymap (PGM) programs

SYNOPSIS

       #include <pgm.h>

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

       gray ** pgm_allocarray( int cols, int rows );

       gray * pgm_allocrow( intcols );

       void pgm_freearray( gray **grays, introws );

       void pgm_freerow( gray *grayrow);

       void pgm_readpgminit( FILE *fp, int *colsP, int *rowsP, gray *maxvalP, int *formatP );

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

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

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

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

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

       void pgm_nextimage( FILE *file, int * const eofP);

       void pgm_check( FILE * file, const enum pm_check_type check_type, const int format, const int cols, const
       int rows, const int maxval, enum pm_check_code * const retval);

       typedef ... gray;

       #define PGM_MAXMAXVAL ...

       #define PGM_OVERALLMAXVAL ...

       extern gray pgm_pbmmaxval;

       #define PGM_FORMAT ...

       #define RPGM_FORMAT ...

       #define PGM_TYPE PGM_FORMAT

       #define PGM_FORMAT_TYPE(format) ...

DESCRIPTION

   TYPES AND CONSTANTS
       Each gray should contain only the values between 0 and PGM_OVERALLMAXVAL.  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.

       PGM_OVERALLMAXVAL is the maximum value of a maxval in a PGM file.  PGM_MAXMAXVAL is the maximum value  of
       a  maxval  in  a  PGM file that is compatible with the PGM format as it existed before April 2000.  It is
       also the maximum value of a maxval that results in the minimum possible  raster  size  for  a  particular
       image.   I.e  an  image  with  a  maxval higher than PGM_MAXMAXVAL cannot be read or generated by old PGM
       processing programs and requires more file space.

       PGM_FORMAT is the format code for a Plain PGM format image file.  RPGM_FORMAT is the format  code  for  a
       Raw  PGM  format image file.  PGM_TYPE is the format type code for the PGM formats.  PGM_FORMAT_TYPE is a
       macro that generates code to compute the format type code of a PBM or PGM format  from  the  format  code
       which is its argument.

   INITIALIZATION
       All PGM programs must call pgm_init() just after invocation, before they process their arguments.

   MEMORY MANAGEMENT
       pgm_allocarray() allocates an array of grays.

       pgm_allocrow() allocates a row of the given number of grays.

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

       pgm_freerow() frees a row of grays allocated with pgm_allocrow().

   READING FILES
       If  a function in this section is called on a PBM format file, it translates the PBM file into a PGM file
       on the fly and functions as if it were called on the equivalent PGM file.  The format value  returned  by
       pgm_readpgminit() is, however, not translated.  It represents the actual format of the PBM file.

       pgm_readpgminit()  reads  the  header  of  a  PGM file, returning all the information from the header and
       leaving the file positioned just after the header.

       pgm_readpgmrow() reads a row of grays into the grayrow array.  format, cols, and maxval  are  the  values
       returned by pgm_readpgminit().

       pgm_readpgm()  reads  an  entire PGM image into memory, returning the allocated array as its return value
       and returning the information from the  header  as  rows,  cols,  and  maxval.   This  function  combines
       pgm_readpgminit(), pgm_allocarray(), and pgm_readpgmrow().

   WRITING FILES
       pgm_writepgminit() writes the header for a PGM file and leaves it positioned just after the header.

       forceplain  is  a  logical  value  that tells pgm_writepgminit() to write a header for a plain PGM format
       file, as opposed to a raw PGM format file.

       pgm_writepgmrow() writes the row grayrow to a PGM  file.   For  meaningful  results,  cols,  maxval,  and
       forceplain must be the same as was used with pgm_writepgminit().

       pgm_writepgm()  write the header and all data for a PGM image.  This function combines pgm_writepgminit()
       and pgm_writepgmrow().

   MISCELLANEOUS
       pgm_nextimage()  positions  a  PGM  input  file  to  the  next  image  in  it  (so  that   a   subsequent
       pgm_readpgminit() reads its header).

       pgm_nextimage() is analogous to pbm_nextimage(), but works on PGM and PBM files.

       pgm_check()  checks  for  the common file integrity error where the file is the wrong size to contain all
       the image data.

       pgm_check() is analogous to pbm_check(), but works on PGM and PBM files.

SEE ALSO

       libpbm(3), libppm(3), libpnm(3)

                                                                                                       libpgm(3)