glenda.party
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term% cat index.txt
COLOR(2)                      System Calls Manual                     COLOR(2)



NAME
       cmap2rgb, cmap2rgba, rgb2cmap - colors and color maps

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

       int  rgb2cmap(int red, int green, int blue)

       int  cmap2rgb(int col)

       int  cmap2rgba(int col)

DESCRIPTION
       These  routines convert between `true color' red/green/blue triples and
       the Plan 9 color map.  See color(6) for  a  description  of  RGBV,  the
       standard color map.

       Rgb2cmap  takes a trio of color values, scaled from 0 (no intensity) to
       255 (full intensity), and returns the index of the color in RGBV  clos‐
       est to that represented by those values.

       Cmap2rgb  decomposes  the  color of RGBV index col and returns a 24-bit
       integer with the low 8 bits representing the blue  value,  the  next  8
       representing  green, and the next 8 representing red.  Cmap2rgba decom‐
       poses the color of RGBV index col and returns a 32-bit integer with the
       low 8 bits representing an alpha value, defined to be 255, and the next
       8 representing blue, then green, then red, as for cmap2rgba shifted  up
       8  bits.   This 32-bit representation is the format used by draw(2) and
       memdraw(2) library routines that take colors as arguments.

SOURCE
       /sys/src/libdraw

SEE ALSO
       graphics(2), allocimage(2), draw(2), image(6), color(6)



                                                                      COLOR(2)