libpnm (3)
functions to support portable anymap programs
SYNOPSIS
Se
P
#include <pnm.h>
cc ... libpnm.a libppm.a libpgm.a libpbm.a
DESCRIPTION
typedef ... xel;
typedef ... xelval;
#define PNM_MAXMAXVAL ...
extern xelval pnm_pbmmaxval;
Each
xel
contains three
xelval s,
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.
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.
void pnm_init( int* argcP, char* argv[] )
All PNM programs must call this routine.
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.
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.
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() .
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 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
AUTHOR
Copyright (C) 1989, 1991 by Tony Hansen and Jef Poskanzer.
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