src/frontends/xforms/Color.C

   1 // -*- C++ -*-
   2 /* This file is part of
   3  * ======================================================
   4  *
   5  *           LyX, The Document Processor
   6  *
   7  *          Copyright 1995 Matthias Ettrich
   8  *          Copyright 1995-2000 The LyX Team.
   9  *
  10  *======================================================*/
  11
  12 #include <config.h>
  13
  14 #include <algorithm> // max
  15 #include <cmath> // floor
  16
  17 #include FORMS_H_LOCATION
  18
  19 #ifdef __GNUG_
  20 #pragma implementation
  21 #endif
  22
  23 #include "Color.h"
  24
  25 using std::max;
  26 using std::min;
  27
  28 static int const nohue = -1;
  29
  30 RGBColor::RGBColor(HSVColor const & hsv)
  31 {
  32         double h = hsv.h;
  33         double const s = hsv.s;
  34         double const v = hsv.v;
  35
  36         double rd, gd, bd;
  37
  38         if (h == nohue || s == 0.0) {
  39                 rd = gd = bd = v;
  40         } else {
  41                 if (h == 360.0) h = 0.0;
  42                 h /= 60.0;
  43
  44                 int const j = max(0, static_cast<int>(::floor(h)));
  45                 //if( j < 0 ) j = 0;
  46
  47                 double const f = h - j;
  48                 double const p = v * (1.0 - s);
  49                 double const q = v * (1.0 - (s * f));
  50                 double const t = v * (1.0 - (s * (1.0 - f)));
  51
  52                 switch (j) {
  53                 case 0:
  54                         rd = v;
  55                         gd = t;
  56                         bd = p;
  57                         break;
  58                 case 1:
  59                         rd = q;
  60                         gd = v;
  61                         bd = p;
  62                         break;
  63                 case 2:
  64                         rd = p;
  65                         gd = v;
  66                         bd = t;
  67                         break;
  68                 case 3:
  69                         rd = p;
  70                         gd = q;
  71                         bd = v;
  72                         break;
  73                 case 4:
  74                         rd = t;
  75                         gd = p;
  76                         bd = v;
  77                         break;
  78                 case 5:
  79                         rd = v;
  80                         gd = p;
  81                         bd = q;
  82                         break;
  83                 default:
  84                         rd = v;
  85                         gd = t;
  86                         bd = p;
  87                         break;  // should never happen.
  88                 }
  89         }
  90
  91         r = static_cast<int>( ::floor((rd * 255.0) + 0.5) );
  92         g = static_cast<int>( ::floor((gd * 255.0) + 0.5) );
  93         b = static_cast<int>( ::floor((bd * 255.0) + 0.5) );
  94 }
  95
  96
  97 HSVColor::HSVColor(RGBColor const & rgb)
  98 {
  99         double const r = rgb.r / 255.0;
 100         double const g = rgb.g / 255.0;
 101         double const b = rgb.b / 255.0;
 102
 103         double const maxval = max( max( r, g ), b );
 104         double const minval = min( min( r, g ), b );
 105
 106         v = maxval;
 107
 108         double const diff = maxval - minval;
 109         if (maxval != 0.0)
 110                 s = diff / maxval;
 111         else
 112                 s = 0.0;
 113
 114         h = nohue;
 115         if (s != 0.0) {
 116                 double const rc = (maxval - r) / diff;
 117                 double const gc = (maxval - g) / diff;
 118                 double const bc = (maxval - b) / diff;
 119
 120                 if (r == maxval)
 121                         h = bc - gc;
 122                 else if (g == maxval)
 123                         h = 2.0 + rc - bc;
 124                 else if (b == maxval)
 125                         h = 4.0 + gc - rc;
 126
 127                 h *= 60.0;
 128                 if (h < 0)
 129                         h += 360;
 130         }
 131 }