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/*
* Motif Tools Library, Version 3.1
* $Id$
*
* Written by David Flanagan.
* Copyright (c) 1992-2001 by David Flanagan.
* All Rights Reserved. See the file COPYRIGHT for details.
* This is open source software. See the file LICENSE for details.
* There is no warranty for this software. See NO_WARRANTY for details.
*
* $Log$
* Revision 1.1.1.1 2001/07/18 11:06:03 root
* Initial checkin.
*
* Revision 1.2 2001/06/12 16:25:28 andre
* *** empty log message ***
*
*
*/
#include <Xmt/Xmt.h>
/*
* RGB <--> HSL conversions were modified from code with the
* following attributions;
*
* A Fast HSL-to-RGB Transform
* by Ken Fishkin, Pixar Inc., January 1989.
* from "Graphics Gems", Academic Press, 1990
*/
#define MIN(a,b) (((a)<(b))?(a):(b))
#define MAX(a,b) (((a)>(b))?(a):(b))
#if NeedFunctionPrototypes
void XmtRGBToHSL(unsigned r, unsigned g, unsigned b,
unsigned *h, unsigned *s, unsigned *l)
#else
void XmtRGBToHSL(r, g, b, h, s, l)
unsigned int r;
unsigned int g;
unsigned int b;
unsigned int *h;
unsigned int *s;
unsigned int *l;
#endif
{
unsigned int v, m, vm, r2, g2, b2;
unsigned int h2, s2, l2;
h2 = s2 = l2 = 0;
v = MAX(r,g);
v = MAX(v,b);
m = MIN(r,g);
m = MIN(m,b);
if ((l2 = (m + v)/2) == 0) goto done;
if ((s2 = vm = (v - m)) == 0) goto done;
else s2 = (s2 << 16) / ((l2 < 32768) ? (v+m) : (131072 - v - m));
r2 = ((((v-r) << 16) / vm) * 60) >> 16;
g2 = ((((v-g) << 16) / vm) * 60) >> 16;
b2 = ((((v-b) << 16) / vm) * 60) >> 16;
if (r == v)
h2 = (g == m ? 300 + b2 : 60 - g2);
else if (g == v)
h2 = (b == m ? 60 + r2 : 180 - b2);
else
h2 = (r == m ? 180 + g2 : 300 - r2);
done:
*h = h2;
*s = (s2 * 100) >> 16;
*l = (l2 * 100) >> 16;
}
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