libppm(3)                                               libppm(3)


NAME
       libppm - functions to support portable pixmap programs

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


DESCRIPTION
   TYPES AND CONSTANTS
       typedef ... pixel;
       typedef ... pixval;
       #define PPMMAXMAXVAL ...
       extern pixval ppmpbmmaxval;

       Each  pixel  contains  three pixvals, each of which should
       contain only  the  values  between  0  and  PPMMAXMAXVAL.
       ppmpbmmaxval  is the maxval used when a PPM program reads
       a PBM file.  Normally it is 1; however, for some programs,
       a larger value gives better results.

       #define PPMFORMAT ...
       #define RPPMFORMAT ...
       #define PPMTYPE PPMFORMAT
       int PPMFORMATTYPE( int format )

       For distinguishing different file formats and types.

       pixval PPMGETR( pixel p )
       pixval PPMGETG( pixel p )
       pixval PPMGETB( pixel p )

       These  three  macros retrieve the red, green or blue value
       from the given pixel.

       void PPMASSIGN( pixel p, pixval red, pixval grn, pixval blu )

       This macro assigns the given red, green and blue values to
       the pixel.

       int PPMEQUAL( pixel p, pixel q )

       This macro checks two pixels for equality.

       void PPMDEPTH( pixel newp, pixel p, pixval oldmaxval, pixval newmaxval )

       This  macro scales the colors of pixel p according the old
       and new maximum values and assigns the new values to newp.
       It is intended to make writing ppmtowhatever easier.

       float PPMLUMIN( pixel p )

       This macro determines the luminance of the pixel p.




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libppm(3)                                               libppm(3)


   MEMORY MANAGEMENT
       pixel** ppmallocarray( int cols, int rows )

       Allocate an array of pixels.

       pixel* ppmallocrow( int cols )

       Allocate a row of the given number of pixels.

       void ppmfreearray( pixel** pixels, int rows )

       Free  the array allocated with ppmallocarray() containing
       the given number of rows.

       void pbmfreerow( pixel* pixelrow )

       Free a row of pixels.

   READING PBM FILES
       void ppmreadppminit( FILE* fp, int* colsP, int* rowsP, pixval* maxvalP, int* formatP )

       Read the header from a PPM  file,  filling  in  the  rows,
       cols, maxval and format variables.

       void ppmreadppmrow( FILE* fp, pixel* pixelrow, int cols, pixval maxval, int format )

       Read  a  row  of  pixels into the pixelrow array.  Format,
       cols, and maxval were filled in by ppmreadppminit().

       pixel** ppmreadppm( FILE* fp, int* colsP, int* rowsP, pixval* maxvalP )

       Read an entire pixmap  file  into  memory,  returning  the
       allocated  array  and filling in the rows, cols and maxval
       variables.   This  function  combines   ppmreadppminit(),
       ppmallocarray() and ppmreadppmrow().

   WRITING FILES
       void ppmwriteppminit( FILE* fp, int cols, int rows, pixval maxval, int forceplain )

       Write  the  header for a portable pixmap file.  The force-
       plain flag forces a plain-format file to  be  written,  as
       opposed to a raw-format one.

       void ppmwriteppmrow( FILE* fp, pixel* pixelrow, int cols, pixval maxval, int forceplain )

       Write a row from a portable pixmap.

       void ppmwriteppm( FILE* fp, pixel** pixels, int cols, int rows, pixval maxval, int forceplain )

       Write the header and all data for a portable pixmap.  This
       function       combines       ppmwriteppminit()       and
       ppmwriteppmrow().





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libppm(3)                                               libppm(3)


   COLOR NAMES
       pixel ppmparsecolor( char* colorname, pixval maxval )

       Parses an ASCII color name into a pixel.  The color can be
       specified in three ways.  One, as a name, assuming that  a
       pointer  to an X11-style color names file was compiled in.
       Two, as an X11-style hexadecimal  number:  #rgb,  #rrggbb,
       #rrrgggbbb, or #rrrrggggbbbb.  Three, as a triplet of dec-
       imal  floating  point   numbers   separated   by   commas:
       r.r,g.g,b.b.

       char* ppmcolorname( pixel* colorP, pixval maxval, int hexok )

       Returns  a pointer to a string describing the given color.
       If the X11 color names file is  available  and  the  color
       appears  in  it, that name is returned.  Otherwise, if the
       hexok  flag  is  true  then  a  hexadecimal  colorspec  is
       returned;  if  hexok is false and the X11 color names file
       is available, then the closest matching color is returned;
       otherwise, it's an error.

SEE ALSO
       pbm(3), pgm(3)

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































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