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/*
* color.c
*
* From xlockmore-4.11's xlock/color.c,
* in turn from swirl.c
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
*/
/*
* Jamie Zawinski has released this code
* for use in lavaps under the GPL (as of 11 November 1999).
*
* The original copyright and license was:
*
* swirl.c Copyright (c) 1994 M.Dobie <mrd@ecs.soton.ac.uk>
* xlock Copyright (c) 1988-91 by Patrick J. Naughton.
* xscreensaver, Copyright (c) 1997 Jamie Zawinski <jwz@netscape.com>
*
* Permission to use, copy, modify, and distribute this software and its
* documentation for any purpose and without fee is hereby granted,
* provided that the above copyright notice appear in all copies and that
* both that copyright notice and this permission notice appear in
* supporting documentation.
*
* This file is provided AS IS with no warranties of any kind. The author
* shall have no liability with respect to the infringement of copyrights,
* trade secrets or any patents by this file or any part thereof. In no
* event will the author be liable for any lost revenue or profits or
* other special, indirect and consequential damages.
*
*/
#include <stdio.h>
#include <math.h>
#include <string.h>
/*
* hsb2rgb is unmodified from xlockmore (This is basically the same as
* the code in Foley, Van Damme, Feiner, Hughes figure 13.34.)
*/
static void
hsb2rgb(double H, double S, double B,
unsigned char *r, unsigned char *g, unsigned char *b)
{
int i;
double f, bb;
unsigned char p, q, t;
H -= floor(H); /* remove anything over 1 */
H *= 6.0;
i = (int) floor(H); /* 0..5 */
f = H - (float) i; /* f = fractional part of H */
bb = 255.0 * B;
p = (unsigned char) (bb * (1.0 - S));
q = (unsigned char) (bb * (1.0 - (S * f)));
t = (unsigned char) (bb * (1.0 - (S * (1.0 - f))));
switch (i) {
case 0:
*r = (unsigned char) bb;
*g = t;
*b = p;
break;
case 1:
*r = q;
*g = (unsigned char) bb;
*b = p;
break;
case 2:
*r = p;
*g = (unsigned char) bb;
*b = t;
break;
case 3:
*r = p;
*g = q;
*b = (unsigned char) bb;
break;
case 4:
*r = t;
*g = p;
*b = (unsigned char) bb;
break;
case 5:
*r = (unsigned char) bb;
*g = p;
*b = q;
break;
}
}
/*
* hsb_to_rgbs is my front-end
* returns an x-compatible color string
* returns memory that must be freed by the caller.
*/
const char *
hsb_to_rgbs(double H, double S, double B)
{
char buf[20];
unsigned char r, g, b;
hsb2rgb(H, S, B, &r, &g, &b);
sprintf(buf, "#%02x%02x%02x", r, g, b);
return strdup(buf);
}
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