plan9 man page for rgbpix

RGBPIX(2)							System Calls Manual							 RGBPIX(2)

NAME
       RGB, rgbpix, rdcolmap, wrcolmap - handle color screens

SYNOPSIS
       #include <u.h>
       #include <libc.h>
       #include <libg.h>

       ulong rgbpix(Bitmap *b, RGB rgb)

       void  rdcolmap(Bitmap *b, RGB *map)

       void  wrcolmap(Bitmap *b, RGB *map)

DESCRIPTION
       Colors are described by the red, green, and blue light intensities, in an RGB datum:

	      typedef
	      struct RGB {
		    ulong red;
		    ulong green;
		    ulong blue;
	      } RGB;

       Black is represented by zero in all three positions and white has the maximum unsigned long value in all three positions.

       Some  of  the graphics functions, such as point (see bitblt(2)), take a pixel value argument, which is a single unsigned long.  For a given
       bitmap, rgbpix returns the pixel value with a color closest to the color represented by the rgb argument.

       There is a colormap associated with each Bitmap.  A colormap is an array of RGBs, of length 2^(2^ldepth), giving the colors for	pixels	0,
       1, 2, etc.

       Rdcolmap  reads	the colormap for the given bitmap into the provided map, which must have enough space to hold it.  Wrcolmap associates the
       given colormap with the given bitmap, if possible.  (The hardware might not allow this.)

SOURCE
       /sys/src/libg

SEE ALSO
       graphics(2)

BUGS
       These functions work only for the screen bitmap.  This interface will have to be refined for screens with more than 8 bits per pixel.

																	 RGBPIX(2)