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 #include FORMS_H_LOCATION
  14
  15 #ifdef __GNUG_
  16 #pragma implementation
  17 #endif
  18
  19 #include <algorithm> // max
  20 #include <cmath> // floor
  21 #include "Color.h"
  22
  23 using std::max;
  24 using std::min;
  25
  26 static int const nohue = -1;
  27
  28 RGBColor::RGBColor(HSVColor const & hsv)
  29 {
  30         double h = hsv.h;
  31         double const s = hsv.s;
  32         double const v = hsv.v;
  33
  34         double rd, gd, bd;
  35
  36         if (h == nohue || s == 0.0) {
  37                 rd = gd = bd = v;
  38         } else {
  39                 if (h == 360.0) h = 0.0;
  40                 h /= 60.0;
  41
  42                 int const j = max(0, static_cast<int>(::floor(h)));
  43                 //if( j < 0 ) j = 0;
  44
  45                 double const f = h - j;
  46                 double const p = v * (1.0 - s);
  47                 double const q = v * (1.0 - (s * f));
  48                 double const t = v * (1.0 - (s * (1.0 - f)));
  49
  50                 switch (j) {
  51                 case 0:
  52                         rd = v;
  53                         gd = t;
  54                         bd = p;
  55                         break;
  56                 case 1:
  57                         rd = q;
  58                         gd = v;
  59                         bd = p;
  60                         break;
  61                 case 2:
  62                         rd = p;
  63                         gd = v;
  64                         bd = t;
  65                         break;
  66                 case 3:
  67                         rd = p;
  68                         gd = q;
  69                         bd = v;
  70                         break;
  71                 case 4:
  72                         rd = t;
  73                         gd = p;
  74                         bd = v;
  75                         break;
  76                 case 5:
  77                         rd = v;
  78                         gd = p;
  79                         bd = q;
  80                         break;
  81                 default:
  82                         rd = v;
  83                         gd = t;
  84                         bd = p;
  85                         break;  // should never happen.
  86                 }
  87         }
  88
  89         r = static_cast<int>( ::floor((rd * 255.0) + 0.5) );
  90         g = static_cast<int>( ::floor((gd * 255.0) + 0.5) );
  91         b = static_cast<int>( ::floor((bd * 255.0) + 0.5) );
  92 }
  93
  94
  95 HSVColor::HSVColor(RGBColor const & rgb)
  96 {
  97         // r, g, b lie in the range 0-1, not 0-255.
  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 = max( 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 }