Provided by: libnetpbm9-dev_10.0-15_i386 bug

NAME

       libpbm - functions to read and write PBM image files

SYNOPSIS

       #include <pbm.h>

       int pm_keymatch(char * str, char * keyword, int minchars);

       int pm_maxvaltobits(int maxval);

       int pm_bitstomaxval(int bits);

       unsigned  int  pm_lcm(unsigned  int  x, unsigned int y, unsigned int z,
       unsigned int limit);

       void pm_message(char * fmt, ... );

       void pm_error(char * fmt, ... );

       void pm_perror(char * fmt, ... );

       void pm_usage(char * usage);

       FILE *pm_openr(char * name)

       FILE *pm_openw(char * name);

       FILE *pm_openr_seekable(const char * name);

       FILE *pm_close(FILE * fp);

       char *pm_read_unknown_size(FILE * fp, long *nread);

       unsigned int pm_tell(FILE * fileP);

       void pm_seek(FILE * fileP, unsigned long filepos);

       bit **pbm_allocarray(int cols,  int rows);

       bit *pbm_allocrow(int cols);

       pbm_freearray(bit **bits, int rows);

       pbm_freerow(bit *bitrow);

       void pbm_readpbminit(FILE * fp, int *colsP, int *rowsP, int *formatP);

       void pbm_readpbmrow(FILE * fp, bit *bitrow, int cols, int format);

       void pbm_readpbmrow_packed(FILE * fp,
       unsigned char * const packed_bits, const int cols, const int format);

       void bit** pbm_readpbm(FILE * fp, int *colsP, int *rowsP);

       void pbm_writepbminit(FILE * fp, int cols, int rows, int forceplain);

       void pbm_writepbmrow(FILE * fp, bit *bitrow, int cols, int forceplain);

       void pbm_writepbmrow_packed(FILE * fp,
       unsigned  char  *  const  packed_bits,  const  int  cols,   const   int
       forceplain);

       void  pbm_writepbm(FILE  *  fp,  bit  **bits,  int  cols, int rows, int
       forceplain);

       #define pbm_packed_bytes(cols) ...

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

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

       int pm_readbigshort(FILE *in, short *sP);

       int pm_writebigshort(FILE *out, short s);

       int pm_readbiglong(FILE *in, long *lP);

       int pm_writebiglong(FILE *out, long l);

       int pm_readlittleshort(FILE *in, short *sP);

       int pm_writelittleshort(FILE *out, short s);

       int pm_readlittlelong(FILE *in, long *lP);

       int pm_writelittlelong(FILE *out, long l);

DESCRIPTION - PACKAGE-WIDE ROUTINES

   KEYWORD MATCHING
       pm_keymatch() does a case-insensitive match  of  str  against  keyword.
       str  can  be a leading sunstring of keyword, but at least minchars must
       be present.

   MAXVAL ARITHMETIC
       pm_maxvaltobits() and pm_bitstomaxval() convert between  a  maxval  and
       the minimum number of bits required to hold it.

       pm_lcm()  computes  the  least common multiple of 3 integers.  You also
       specify a limit and if  the  LCM  would  be  higher  than  that  limit,
       pm_lcm() just returns that limit.

   MESSAGES AND ERRORS
       pm_message()  is  a  printf()  style  routine to write an informational
       message to the Standard Error file stream.  pm_message() suppresses the
       message,  however,  if  the  user  specified  the  -quiet option on the
       command line.  See the initialization functions, e.g.  pbm_init(),  for
       information  on the -quiet option.  Note that Netpbm programs are often
       used  interactively,  but  also  often  used  by  programs.    In   the
       interactive  case,  it is nice to issue messages about what the program
       is  doing,  but  in  the  program  case,  such  messages  are   usually
       undesirable.   By  using  pm_message()  for all your messages, you make
       your program usable in both cases.  Without any effort  on  your  part,
       program  users of your program can avoid the messages by specifying the
       -quiet option.

       pm_error() is a printf() style routine that writes an error message  to
       the  Standard Error file stream and exits the program with an exit code
       of 1.

   GENERIC FILE ACCESS
       pm_openr() opens the given file for  reading,  with  appropriate  error
       checking.  A filename of - is taken to mean Standard Input.  pm_openw()
       opens the given file for  writing,  with  appropriate  error  checking.
       pm_close() closes the file descriptor, with appropriate error checking.

       pm_openr_seekable()  appears to open the file just like pm_openr(), but
       the file thus opened is guaranteed to be seekable (you can use  ftell()
       and  fseek() on it).  pm_openr_seekable() pulls this off by copying the
       entire file to a temporary file  and  giving  you  the  handle  of  the
       temporary  file, if it has to.  If the file you name is a regular file,
       it's already seekable so pm_openr_seekable() just does the  same  thing
       as  pm_openr().   But  if  it  is,  say, a pipe, it isn't seekable.  So
       pm_openr_seekable() reads the pipe until EOF  into  a  temporary  file,
       then  opens that temporary file and returns the handle of the temporary
       file.  The temporary file is seekable.

       The file pm_openr_seekable() creates is one that the  operating  system
       recognizes  as  temporary, so when you close the file, by any means, it
       gets deleted.

       You need a seekable file if you intend to make multiple passes  through
       the file.  The only alternative is to read the entire image into memory
       and work from that copy.  That may use too much memory.  Note that  the
       image  takes  less  space in the file cache than in a buffer in memory.
       As much as 96 times less space!  Each  sample  is  an  integer  in  the
       buffer,  which  is  usually  96  bits.  In the file, a sample may be as
       small as 1 bit and rarely more than 8 bits.

       pm_read_unknown_size() reads an entire file or input stream of  unknown
       size  to  a buffer.  Allocate memory more memory as needed. The calling
       routine has to free the allocated buffer with free().

       pm_read_unknown_size() returns a pointer to the allocated  buffer.  The
       nread argument returns the number of bytes read.

       pm_tell()  returns  a  handle  for  the  current  position of the file,
       whether it be the header or a row of the raster.  Use the handle as  an
       argument  to  pm_seek()  to  reposition the file there later.  The file
       must  be  seekable  (which  you  can  ensure   by   opening   it   with
       pm_openr_seekable())orthismayfail.

   ENDIAN I/O
       pm_readbigshort(),         pm_writebigshort(),        pm_readbiglong(),
       pm_writebiglong(),     pm_readlittleshort(),     pm_writelittleshort(),
       pm_readlittlelong(),  and pm_writelittlelong() are routines to read and
       write short and long ints in either big- or little-endian  byte  order.
       The  return  value is 0 upon success and -1 upon failure (either EOF or
       I/O error).

DESCRIPTION - PBM-SPECIFIC ROUTINES

   TYPES AND CONSTANTS
       typedef ... bit;

       #define PBM_WHITE ...

       #define PBM_BLACK ...

       Each bit should contain only the values of PBM_WHITE or PBM_BLACK.

       #define PBM_FORMAT ...

       #define RPBM_FORMAT ...

       #define PBM_TYPE PBM_FORMAT

       #define PBM_FORMAT_TYPE(f) ...

       These are for distinguishing different file formats and types.

   INITIALIZATION
       All PBM programs must  call  pbm_init  just  after  invocation,  before
       processing arguments.

   MEMORY MANAGEMENT
       pbm_allocarray()  allocates an array of bits.  pbm_allocrow() allocates
       a row of the given number of bits.   pbm_freearray()  frees  the  array
       allocated  with  pbm_allocarray()  containing the given number of rows.
       pbm_freerow() frees a row of bits.

   READING PBM IMAGE FILES
       pbm_readpbminit() reads the header from a PBM  image  in  a  PBM  file,
       filling in the rows, cols and format variables.  pbm_readpbmrow() reads
       a row of bits into the bitrow array.  Format and cols were filled in by
       pbm_readpbminit().    pbm_readpbmrow_packed()   is  like  pbm_readrow()
       except  instead  of  returning  a  bits  array,  it  returns  an  array
       packed_bits of bytes with the pixels of the image row packed into them.
       The pixels are in order from left to right across the row and from  the
       beginning  of  the  array  to  the end.  Within a byte, the bits are in
       order from the most significant bit to the least significant  bit.   If
       the  number  of pixels in the row is not a multiple of 8, the last byte
       returned is padded on the least  signficant  bit  side  with  undefined
       bits.  White is represented by a PBM_WHITE bit; black by PBM_BLACK.

       pbm_readpbm()  reads  an  entire bitmap file into memory, returning the
       allocated array and filling in  the  rows  and  cols  variables.   This
       function     combines     pbm_readpbminit(),    pbm_allocarray()    and
       pbm_readpbmrow().

   WRITING PBM IMAGE FILES
       pbm_writepbminit() writes the header for a PBM image  in  a  PBM  file.
       forceplain  is  a  boolean  value specifying that a plain format (text)
       file  to  be  written,  as  opposed  to  a  raw  format  (binary)  one.
       pbm_writepbmrow() writes a row to a PBM file.  pbm_writepbmrow_packed()
       is the same as pbm_writepbmrow() except that  you  supply  the  row  to
       write as an array of bytes packed with bits instead of as a bits array.
       The  format  of  packed_bits  is  the  same   as   that   returned   by
       pbm_readpbmrow().

       pbm_writepbm()  writes the header and all data for a PBM image to a PBM
       file.  This function combines pbm_writepbminit() and pbm_writepbmrow().

   MISCELLANEOUS
       pbm_nextimage() positions a PBM input file to the next image in it  (so
       that a subsequent pbm_readpbminit() reads its header).

       Immediately  before  a  call  to  pbm_nextimage(),  the  file  must  be
       positioned either at its beginning (i.e. nothing has been read from the
       file yet) or just after an image (i.e. as left by a pbm_readpbmrow() of
       the last row in the image).

       In effect, then, all pbm_nextimage() does is test whether  there  is  a
       next image or the file is positioned at end-of-file.

       If pbm_nextimage() successfully positions to the next image, it returns
       *eofP false (0).  If there is no next image in  the  file,  it  returns
       *eofP  true (1).  If it can't position or determine the file status due
       to a file error, it issues an error message and exits the program  with
       an error exit code.

       pbm_check()  checks  for the common file integrity error where the file
       is the wrong size to contain all the image data.   pbm_check()  assumes
       the  file  is positioned after an image header (as if pbm_readpbminit()
       was the last operation on the file).  It checks the file size to see if
       the number of bytes left in the file are the number required to contain
       the image raster.  If the file is too  short,  pbm_check()  causes  the
       program  to  exit  with  an  error  message  and error completion code.
       Otherwise, it returns one of the following values (enumerations of  the
       enum pm_check_code type) as *retval:

       PM_CHECK_OK
              The  file's  size  is exactly what is required to hold the image
              raster.

       PM_CHECK_UNKNOWN_TYPE
              format is not a format whose size  pbm_check()  can  anticipate.
              The  only  format  with  which  pbm_check()  can deal is raw PBM
              format.

       PM_CHECK_TOO_LONG
              The file is longer than it needs to  be  to  contain  the  image
              raster.  The extra data might be another image.

       PM_CHECK_UNCHECKABLE
              The  file is not a kind that has a predictable size, so there is
              no simple way for pbm_check() to know if it is the  right  size.
              Only  a  regular  file has predictable size.  A pipe is a common
              example of a file that does not.

       check_type must have the value PM_CHECK_BASIC (an enumerated  value  of
       the   pm_check_type   enumerated   type).   Otherwise,  the  effect  of
       pbm_check() is unpredictable.  This argument exists for future backward
       compatible expansion of the function of pbm_check().

SEE ALSO

       libpgm(3), libppm(3), libpnm(3), pbm(5)

AUTHOR

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

                                                                     libpbm(3)