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 namespace {
  29
  30 int const nohue = -1;
  31
  32 } // namespace anon
  33
  34 RGBColor::RGBColor(HSVColor const & hsv)
  35 {
  36         double h = hsv.h;
  37         double const s = hsv.s;
  38         double const v = hsv.v;
  39
  40         double rd, gd, bd;
  41
  42         if (h == nohue || s == 0.0) {
  43                 rd = gd = bd = v;
  44         } else {
  45                 if (h == 360.0) h = 0.0;
  46                 h /= 60.0;
  47
  48                 int const j = max(0, static_cast<int>(::floor(h)));
  49                 //if( j < 0 ) j = 0;
  50
  51                 double const f = h - j;
  52                 double const p = v * (1.0 - s);
  53                 double const q = v * (1.0 - (s * f));
  54                 double const t = v * (1.0 - (s * (1.0 - f)));
  55
  56                 switch (j) {
  57                 case 0:
  58                         rd = v;
  59                         gd = t;
  60                         bd = p;
  61                         break;
  62                 case 1:
  63                         rd = q;
  64                         gd = v;
  65                         bd = p;
  66                         break;
  67                 case 2:
  68                         rd = p;
  69                         gd = v;
  70                         bd = t;
  71                         break;
  72                 case 3:
  73                         rd = p;
  74                         gd = q;
  75                         bd = v;
  76                         break;
  77                 case 4:
  78                         rd = t;
  79                         gd = p;
  80                         bd = v;
  81                         break;
  82                 case 5:
  83                         rd = v;
  84                         gd = p;
  85                         bd = q;
  86                         break;
  87                 default:
  88                         rd = v;
  89                         gd = t;
  90                         bd = p;
  91                         break;  // should never happen.
  92                 }
  93         }
  94
  95         r = static_cast<int>( ::floor((rd * 255.0) + 0.5) );
  96         g = static_cast<int>( ::floor((gd * 255.0) + 0.5) );
  97         b = static_cast<int>( ::floor((bd * 255.0) + 0.5) );
  98 }
  99
 100
 101 HSVColor::HSVColor(RGBColor const & rgb)
 102 {
 103         double const r = rgb.r / 255.0;
 104         double const g = rgb.g / 255.0;
 105         double const b = rgb.b / 255.0;
 106
 107         double const maxval = max( max( r, g ), b );
 108         double const minval = min( min( r, g ), b );
 109
 110         v = maxval;
 111
 112         double const diff = maxval - minval;
 113         if (maxval != 0.0)
 114                 s = diff / maxval;
 115         else
 116                 s = 0.0;
 117
 118         h = nohue;
 119         if (s != 0.0) {
 120                 double const rc = (maxval - r) / diff;
 121                 double const gc = (maxval - g) / diff;
 122                 double const bc = (maxval - b) / diff;
 123
 124                 if (r == maxval)
 125                         h = bc - gc;
 126                 else if (g == maxval)
 127                         h = 2.0 + rc - bc;
 128                 else if (b == maxval)
 129                         h = 4.0 + gc - rc;
 130
 131                 h *= 60.0;
 132                 if (h < 0)
 133                         h += 360;
 134         }
 135 }