1 cfa37a7b 2004-04-10 devnull .TH COLOR 3
 2 cfa37a7b 2004-04-10 devnull .SH NAME
 3 cfa37a7b 2004-04-10 devnull cmap2rgb, cmap2rgba, rgb2cmap \- colors and color maps
 4 cfa37a7b 2004-04-10 devnull .SH SYNOPSIS
 5 cfa37a7b 2004-04-10 devnull .B #include <u.h>
 6 cfa37a7b 2004-04-10 devnull .br
 7 cfa37a7b 2004-04-10 devnull .B #include <libc.h>
 8 cfa37a7b 2004-04-10 devnull .br
 9 cfa37a7b 2004-04-10 devnull .B #include <draw.h>
10 cfa37a7b 2004-04-10 devnull .PP
11 cfa37a7b 2004-04-10 devnull .B
12 cfa37a7b 2004-04-10 devnull int	rgb2cmap(int red, int green, int blue)
13 cfa37a7b 2004-04-10 devnull .PP
14 cfa37a7b 2004-04-10 devnull .B
15 cfa37a7b 2004-04-10 devnull int	cmap2rgb(int col)
16 cfa37a7b 2004-04-10 devnull .PP
17 cfa37a7b 2004-04-10 devnull .B
18 cfa37a7b 2004-04-10 devnull int	cmap2rgba(int col)
19 cfa37a7b 2004-04-10 devnull .SH DESCRIPTION
20 cfa37a7b 2004-04-10 devnull These routines convert between `true color' red/green/blue triples and the Plan 9 color map.
21 cfa37a7b 2004-04-10 devnull See
22 d32deab1 2020-08-16 rsc .MR color (7)
23 cfa37a7b 2004-04-10 devnull for a description of RGBV, the standard color map.
24 cfa37a7b 2004-04-10 devnull .PP
25 cfa37a7b 2004-04-10 devnull .I Rgb2cmap
26 cfa37a7b 2004-04-10 devnull takes a trio of color values, scaled from 0 (no intensity) to 255 (full intensity),
27 cfa37a7b 2004-04-10 devnull and returns the index of the color in RGBV closest to that represented
28 cfa37a7b 2004-04-10 devnull by those values.
29 cfa37a7b 2004-04-10 devnull .PP
30 cfa37a7b 2004-04-10 devnull .I Cmap2rgb
31 cfa37a7b 2004-04-10 devnull decomposes the color of RGBV index
32 cfa37a7b 2004-04-10 devnull .I col
33 cfa37a7b 2004-04-10 devnull and returns a 24-bit integer with the low 8 bits representing the blue value,
34 cfa37a7b 2004-04-10 devnull the next 8 representing green, and the next 8 representing red.
35 cfa37a7b 2004-04-10 devnull .I Cmap2rgba
36 cfa37a7b 2004-04-10 devnull decomposes the color of RGBV index
37 cfa37a7b 2004-04-10 devnull .I col
38 cfa37a7b 2004-04-10 devnull and returns a 32-bit integer with the low 8 bits representing an alpha value,
39 cfa37a7b 2004-04-10 devnull defined to be 255,
40 cfa37a7b 2004-04-10 devnull and the next 8 representing blue, then green, then red, as for
41 cfa37a7b 2004-04-10 devnull .I cmap2rgba
42 cfa37a7b 2004-04-10 devnull shifted up 8 bits.
43 cfa37a7b 2004-04-10 devnull This 32-bit representation is the format used by 
44 d32deab1 2020-08-16 rsc .MR draw (3)
45 cfa37a7b 2004-04-10 devnull and
46 d32deab1 2020-08-16 rsc .MR memdraw (3)
47 cfa37a7b 2004-04-10 devnull library routines that
48 cfa37a7b 2004-04-10 devnull take colors as arguments.
49 cfa37a7b 2004-04-10 devnull .SH SOURCE
50 c3674de4 2005-01-11 devnull .B \*9/src/libdraw
51 cfa37a7b 2004-04-10 devnull .SH SEE ALSO
52 d32deab1 2020-08-16 rsc .MR graphics (3) ,
53 d32deab1 2020-08-16 rsc .MR allocimage (3) ,
54 d32deab1 2020-08-16 rsc .MR draw (3) ,
55 d32deab1 2020-08-16 rsc .MR image (7) ,
56 d32deab1 2020-08-16 rsc .MR color (7)