src/frontends/xforms/Color.C

   1 /**
   2  * \file Color.C
   3  * Copyright 2002 the LyX Team
   4  * Read the file COPYING
   5  *
   6  * \author Angus Leeming, a.leeming@ic.ac.uk
   7  */
   8
   9 #include <config.h>
  10
  11 #ifdef __GNUG__
  12 #pragma implementation
  13 #endif
  14
  15 #include "Color.h"
  16 #include <algorithm> // max
  17 #include <cmath> // floor
  18 #include FORMS_H_LOCATION
  19
  20 using std::max;
  21 using std::min;
  22
  23 namespace {
  24
  25 int const nohue = -1;
  26
  27 } // namespace anon
  28
  29 RGBColor::RGBColor(HSVColor const & hsv)
  30 {
  31         double h = hsv.h;
  32         double const s = hsv.s;
  33         double const v = hsv.v;
  34
  35         double rd, gd, bd;
  36
  37         if (h == nohue || s == 0.0) {
  38                 rd = gd = bd = v;
  39         } else {
  40                 if (h == 360.0) h = 0.0;
  41                 h /= 60.0;
  42
  43                 int const j = max(0, static_cast<int>(::floor(h)));
  44                 //if (j < 0) j = 0;
  45
  46                 double const f = h - j;
  47                 double const p = v * (1.0 - s);
  48                 double const q = v * (1.0 - (s * f));
  49                 double const t = v * (1.0 - (s * (1.0 - f)));
  50
  51                 switch (j) {
  52                 case 0:
  53                         rd = v;
  54                         gd = t;
  55                         bd = p;
  56                         break;
  57                 case 1:
  58                         rd = q;
  59                         gd = v;
  60                         bd = p;
  61                         break;
  62                 case 2:
  63                         rd = p;
  64                         gd = v;
  65                         bd = t;
  66                         break;
  67                 case 3:
  68                         rd = p;
  69                         gd = q;
  70                         bd = v;
  71                         break;
  72                 case 4:
  73                         rd = t;
  74                         gd = p;
  75                         bd = v;
  76                         break;
  77                 case 5:
  78                         rd = v;
  79                         gd = p;
  80                         bd = q;
  81                         break;
  82                 default:
  83                         rd = v;
  84                         gd = t;
  85                         bd = p;
  86                         break;  // should never happen.
  87                 }
  88         }
  89
  90         r = static_cast<int>(::floor((rd * 255.0) + 0.5));
  91         g = static_cast<int>(::floor((gd * 255.0) + 0.5));
  92         b = static_cast<int>(::floor((bd * 255.0) + 0.5));
  93 }
  94
  95
  96 HSVColor::HSVColor(RGBColor const & rgb)
  97 {
  98         double const r = rgb.r / 255.0;
  99         double const g = rgb.g / 255.0;
 100         double const b = rgb.b / 255.0;
 101
 102         double const maxval = max( max( r, g), b);
 103         double const minval = min( min( r, g), b);
 104
 105         v = maxval;
 106
 107         double const diff = maxval - minval;
 108         if (maxval != 0.0)
 109                 s = diff / maxval;
 110         else
 111                 s = 0.0;
 112
 113         h = nohue;
 114         if (s != 0.0) {
 115                 double const rc = (maxval - r) / diff;
 116                 double const gc = (maxval - g) / diff;
 117                 double const bc = (maxval - b) / diff;
 118
 119                 if (r == maxval)
 120                         h = bc - gc;
 121                 else if (g == maxval)
 122                         h = 2.0 + rc - bc;
 123                 else if (b == maxval)
 124                         h = 4.0 + gc - rc;
 125
 126                 h *= 60.0;
 127                 if (h < 0)
 128                         h += 360;
 129         }
 130 }