components/x11/xcolor/src/HSBmap.c

   1 /*-
   2  * HSBmap.c - Create an HSB ramp.
   3  *
   4  * Copyright (c) 1991, 2011, Oracle and/or its affiliates. All rights reserved.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a
   7  * copy of this software and associated documentation files (the "Software"),
   8  * to deal in the Software without restriction, including without limitation
   9  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  10  * and/or sell copies of the Software, and to permit persons to whom the
  11  * Software is furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice (including the next
  14  * paragraph) shall be included in all copies or substantial portions of the
  15  * Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  22  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  23  * DEALINGS IN THE SOFTWARE.
  24  *
  25  * Author: Patrick J. Naughton
  26  * naughton@sun.com
  27  */
  28
  29
  30 #include <sys/types.h>
  31 #include <math.h>
  32 #include "xcolor.h"
  33
  34 static void
  35 hsb2rgb(
  36     double      H,
  37     double      S,
  38     double      B,
  39     u_char     *r,
  40     u_char     *g,
  41     u_char     *b)
  42
  43 {
  44     register int i;
  45     register double f,
  46                 bb;
  47     register u_char p,
  48                 q,
  49                 t;
  50
  51     H -= floor(H);              /* remove anything over 1 */
  52     H *= 6.0;
  53     i = floor(H);               /* 0..5 */
  54     f = H - (float) i;          /* f = fractional part of H */
  55     bb = 255.0 * B;
  56     p = (u_char) (bb * (1.0 - S));
  57     q = (u_char) (bb * (1.0 - (S * f)));
  58     t = (u_char) (bb * (1.0 - (S * (1.0 - f))));
  59     switch (i) {
  60     case 0:
  61         *r = (u_char) bb;
  62         *g = t;
  63         *b = p;
  64         break;
  65     case 1:
  66         *r = q;
  67         *g = (u_char) bb;
  68         *b = p;
  69         break;
  70     case 2:
  71         *r = p;
  72         *g = (u_char) bb;
  73         *b = t;
  74         break;
  75     case 3:
  76         *r = p;
  77         *g = q;
  78         *b = (u_char) bb;
  79         break;
  80     case 4:
  81         *r = t;
  82         *g = p;
  83         *b = (u_char) bb;
  84         break;
  85     case 5:
  86         *r = (u_char) bb;
  87         *g = p;
  88         *b = q;
  89         break;
  90     }
  91 }
  92
  93
  94 void
  95 HSBramp(
  96     double      h1,
  97     double      s1,
  98     double      b1,
  99     double      h2,
 100     double      s2,
 101     double      b2,
 102     int         start,
 103     int         end,
 104     u_char     *red,
 105     u_char     *green,
 106     u_char     *blue)
 107 {
 108     double      dh,
 109                 ds,
 110                 db;
 111     register u_char *r,
 112                *g,
 113                *b;
 114     register int i;
 115
 116     r = red;
 117     g = green;
 118     b = blue;
 119     dh = (h2 - h1) / 255.0;
 120     ds = (s2 - s1) / 255.0;
 121     db = (b2 - b1) / 255.0;
 122     for (i = start; i <= end; i++) {
 123         hsb2rgb(h1, s1, b1, r++, g++, b++);
 124         h1 += dh;
 125         s1 += ds;
 126         b1 += db;
 127     }
 128 }