libppm(3)                        UNIX System V                        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 PPM_MAXMAXVAL ...
      extern pixval ppm_pbmmaxval;

      Each pixel contains three pixvals, each of which should contain only the
      values between 0 and PPM_MAXMAXVAL.  ppm_pbmmaxval 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 PPM_FORMAT ...
      #define RPPM_FORMAT ...
      #define PPM_TYPE PPM_FORMAT
      int PPM_FORMAT_TYPE( int format )

      For distinguishing different file formats and types.

      pixval PPM_GETR( pixel p )
      pixval PPM_GETG( pixel p )
      pixval PPM_GETB( pixel p )

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

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

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

      int PPM_EQUAL( pixel p, pixel q )

      This macro checks two pixels for equality.

      void PPM_DEPTH( 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 PPM_LUMIN( pixel p )

      This macro determines the luminance of the pixel p.



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libppm(3)                        UNIX System V                        libppm(3)


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

      Allocate an array of pixels.

      pixel* ppm_allocrow( int cols )

      Allocate a row of the given number of pixels.

      void ppm_freearray( pixel** pixels, int rows )

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

      void pbm_freerow( pixel* pixelrow )

      Free a row of pixels.

   READING PBM FILES
      void ppm_readppminit( 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 ppm_readppmrow( 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 ppm_readppminit().

      pixel** ppm_readppm( 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
      ppm_readppminit(), ppm_allocarray() and ppm_readppmrow().

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

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

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

      Write a row from a portable pixmap.

      void ppm_writeppm( 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 ppm_writeppminit() and ppm_writeppmrow().





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libppm(3)                        UNIX System V                        libppm(3)


   COLOR NAMES
      pixel ppm_parsecolor( 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 decimal floating point numbers separated by commas: r.r,g.g,b.b.

      char* ppm_colorname( 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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