2
* Motif Tools Library, Version 3.1
5
* Written by David Flanagan.
6
* Copyright (c) 1992-2001 by David Flanagan.
7
* All Rights Reserved. See the file COPYRIGHT for details.
8
* This is open source software. See the file LICENSE for details.
9
* There is no warranty for this software. See NO_WARRANTY for details.
12
* Revision 1.1.1.1 2001/07/18 11:06:03 root
15
* Revision 1.2 2001/06/12 16:25:28 andre
16
* *** empty log message ***
24
* RGB <--> HSL conversions were modified from code with the
25
* following attributions;
27
* A Fast HSL-to-RGB Transform
28
* by Ken Fishkin, Pixar Inc., January 1989.
29
* from "Graphics Gems", Academic Press, 1990
32
#define MIN(a,b) (((a)<(b))?(a):(b))
33
#define MAX(a,b) (((a)>(b))?(a):(b))
35
#if NeedFunctionPrototypes
36
void XmtRGBToHSL(unsigned r, unsigned g, unsigned b,
37
unsigned *h, unsigned *s, unsigned *l)
39
void XmtRGBToHSL(r, g, b, h, s, l)
48
unsigned int v, m, vm, r2, g2, b2;
49
unsigned int h2, s2, l2;
58
if ((l2 = (m + v)/2) == 0) goto done;
59
if ((s2 = vm = (v - m)) == 0) goto done;
60
else s2 = (s2 << 16) / ((l2 < 32768) ? (v+m) : (131072 - v - m));
62
r2 = ((((v-r) << 16) / vm) * 60) >> 16;
63
g2 = ((((v-g) << 16) / vm) * 60) >> 16;
64
b2 = ((((v-b) << 16) / vm) * 60) >> 16;
67
h2 = (g == m ? 300 + b2 : 60 - g2);
69
h2 = (b == m ? 60 + r2 : 180 - b2);
71
h2 = (r == m ? 180 + g2 : 300 - r2);
75
*s = (s2 * 100) >> 16;
76
*l = (l2 * 100) >> 16;