libpnm

NAME
SYNOPSIS
DESCRIPTION
SEE ALSO
AUTHOR

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.