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 #ifdef __GNUG_
  15 #pragma implementation
  16 #endif
  17
  18 #include <algorithm> // max
  19 #include <cmath> // floor
  20 #include "Color.h"
  21
  22 using std::max;
  23 using std::min;
  24
  25 static int const nohue = -1;
  26
  27 RGB::RGB( HSV const & hsv )
  28 {
  29         double h = hsv.h;
  30         double s = hsv.s;
  31         double v = hsv.v;
  32
  33         double rd, gd, bd;
  34
  35         if( h == nohue || s == 0.0 ) {
  36                 rd = gd = bd = v;
  37         } else {
  38                 if( h == 360.0 ) h = 0.0;
  39                 h /= 60.0;
  40
  41                 int j = static_cast<int>( ::floor(h) );
  42                 if( j < 0 ) j = 0;
  43
  44                 double f = h - j;
  45                 double p = v * (1.0 - s);
  46                 double q = v * (1.0 - (s*f));
  47                 double t = v * (1.0 - (s*(1.0 - f)));
  48
  49                 switch( j ) {
  50                 case 0:
  51                         rd = v;
  52                         gd = t;
  53                         bd = p;
  54                         break;
  55                 case 1:
  56                         rd = q;
  57                         gd = v;
  58                         bd = p;
  59                         break;
  60                 case 2:
  61                         rd = p;
  62                         gd = v;
  63                         bd = t;
  64                         break;
  65                 case 3:
  66                         rd = p;
  67                         gd = q;
  68                         bd = v;
  69                         break;
  70                 case 4:
  71                         rd = t;
  72                         gd = p;
  73                         bd = v;
  74                         break;
  75                 case 5:
  76                         rd = v;
  77                         gd = p;
  78                         bd = q;
  79                         break;
  80                 default:
  81                         rd = v;
  82                         gd = t;
  83                         bd = p;
  84                         break;  // should never happen.
  85                 }
  86         }
  87
  88         r = static_cast<int>( ::floor((rd * 255.0) + 0.5) );
  89         g = static_cast<int>( ::floor((gd * 255.0) + 0.5) );
  90         b = static_cast<int>( ::floor((bd * 255.0) + 0.5) );
  91 }
  92
  93
  94 HSV::HSV( RGB const & rgb )
  95 {
  96         // r, g, b lie in the range 0-1, not 0-255.
  97         double r = rgb.r / 255.0;
  98         double g = rgb.g / 255.0;
  99         double b = rgb.b / 255.0;
 100
 101         double maxval = max( max( r, g ), b );
 102         double minval = max( min( r, g ), b );
 103
 104         v = maxval;
 105
 106         double diff = maxval - minval;
 107         if( maxval != 0.0 )
 108                 s = diff / maxval;
 109         else
 110                 s = 0.0;
 111
 112         h = nohue;
 113         if( s != 0.0 ) {
 114                 double rc = (maxval - r) / diff;
 115                 double gc = (maxval - g) / diff;
 116                 double bc = (maxval - b) / diff;
 117
 118                 if( r == maxval )
 119                         h = bc - gc;
 120                 else if( g == maxval )
 121                         h = 2.0 + rc - bc;
 122                 else if( b == maxval )
 123                         h = 4.0 + gc - rc;
 124
 125                 h *= 60.0;
 126                 if ( h < 0 )
 127                         h += 360;
 128         }
 129 }
 130