libpnm(3)

NAME
libpnm - functions to support portable anymap programs

SYNOPSIS
#include <pnm.h> cc ... libpnm.a libppm.a libpgm.a libpbm.a

DESCRIPTION

  TYPES AND CONSTANTS
typedef ... xel; typedef ... xelval; #define PNM_MAXMAXVAL ... extern xelval pnm_pbmmaxval; Each xel contains three xelvals, each of which should contain only the values between 0 and PNM_MAXMAXVAL. pnm_pbmmaxval is the maxval used when a PNM program reads a PBM file. Normally it is 1; however, for some programs, a larger value gives better results.

  XEL MANIPULATIONS
xelval PNM_GET1( xel x ) This macro extracts a single value from an xel, when you know it's from a PBM or PGM file. When it's from a PPM file, use PPM_GETR(), PPM_GETG(), and PPM_GETB(). void PNM_ASSIGN1( xel x, xelval v ) This macro assigns a single value to an xel, when you know it's from a PBM or PGM file. When it's from a PPM file, use PPM_ASSIGN(). int PNM_EQUAL( xel x, xel y ) This macro checks two xels for equality. int PNM_FORMAT_TYPE( int format ) For distinguishing different file types.

  INITIALIZATION
void pnm_init( int* argcP, char* argv[] ) All PNM programs must call this routine.

  MEMORY MANAGEMENT
xel** pnm_allocarray( int cols, int rows ) Allocate an array of xels. xel* pnm_allocrow( int cols ) Allocate a row of the given number of xels. void pnm_freearray( xel** xels, int rows ) Free the array allocated with pnm_allocarray() containing the given number of rows. void pnm_freerow( xel* xelrow ) Free a row of xels.

  READING FILES
void pnm_readpnminit( FILE* fp, int* colsP, int* rowsP, xelval* maxvalP, int* formatP ) Read the header from a PNM file, filling in the rows, cols, maxval and format variables. void pnm_readpnmrow( FILE* fp, xel* xelrow, int cols, xelval maxval, int format ) Read a row of xels into the xelrow array. Format, cols, and maxval were filled in by pnm_readpnminit(). xel** pnm_readpnm( FILE* fp, int* colsP, int* rowsP, xelval* maxvalP, int* formatP ) Read an entire anymap file into memory, returning the allocated array and filling in the rows, cols, maxval, and format variables. This function combines pnm_readpnminit(), pnm_allocarray() and pnm_readpnmrow(). Unlike the equivalent functions in PBM, PGM, and PPM, it returns the format so you can tell what type the file is.

  WRITING FILES
void pnm_writepnminit( FILE* fp, int cols, int rows, xelval maxval, int format, int forceplain ) Write the header for a portable anymap file. Unlike the equivalent functions in PBM, PGM, and PPM, you have to specify the output type. The forceplain flag forces a plain-format file to be written, as opposed to a raw-format one. void pnm_writepnmrow( FILE* fp, xel* xelrow, int cols, xelval maxval, int format, int forceplain ) Write a row from a portable anymap. void pnm_writepnm( FILE* fp, xel** xels, int cols, int rows, xelval maxval, int format, int forceplain ) Write the header and all data for a portable anymap. This function combines pnm_writepnminit() and pnm_writepnmrow().

  FORMAT PROMOTION
void pnm_promoteformatrow( xel* xelrow, int cols, xelval maxval, int format, xelval newmaxval, int newformat ) Promote a row of xels from one maxval and format to a new set. Used when combining multiple anymaps of different types - just take the max of the maxvals and the max of the formats, and promote them all to that. void pnm_promoteformat( xel** xels, int cols, int rows, xelval maxval, int format, xelval newmaxval, int newformat ) Promote an entire anymap.

  XEL MANIPULATION
xel pnm_whitexel( xelval maxval, int format ) xel pnm_blackxel( xelval maxval, int format ) Return a white or black xel for the given maxval and format. void pnm_invertxel( xel* x, xelval maxval, int format ) Invert an xel. xel pnm_backgroundxelrow( xel* xelrow, int cols, xelval maxval, int format ) Figure out an appropriate background xel based on this row. xel pnm_backgroundxel( xel** xels, int cols, int rows, xelval maxval, int format ) Figure out a background xel based on an entire anymap. This can do a slightly better job than pnm_backgroundxelrow().

SEE ALSO
pbm(3), pgm(3), ppm(3)

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