rainbowstream/image.c

   1 /*
   2  * This source is borrowed from folowwing link
   3  * https://github.com/jart/fabulous/blob/master/fabulous/_xterm256.c
   4  * I make a slightly change to fit my module here
   5  */
   6 typedef struct {
   7         int r;
   8         int g;
   9         int b;
  10 } rgb_t;
  11 int CUBE_STEPS[] = { 0x00, 0x5F, 0x87, 0xAF, 0xD7, 0xFF };
  12 rgb_t BASIC16[] =
  13       { {   0,   0,   0 }, { 205,   0,   0}, {   0, 205,   0 },
  14         { 205, 205,   0 }, {   0,   0, 238}, { 205,   0, 205 },
  15         {   0, 205, 205 }, { 229, 229, 229}, { 127, 127, 127 },
  16         { 255,   0,   0 }, {   0, 255,   0}, { 255, 255,   0 },
  17         {  92,  92, 255 }, { 255,   0, 255}, {   0, 255, 255 },
  18         { 255, 255, 255 } };
  19 rgb_t COLOR_TABLE[256];
  20
  21
  22 rgb_t ansi_to_rgb(int xcolor)
  23 {
  24   rgb_t res;
  25   if (xcolor < 16) {
  26     res = BASIC16[xcolor];
  27   } else if (16 <= xcolor && xcolor <= 231) {
  28     xcolor -= 16;
  29     res.r = CUBE_STEPS[(xcolor / 36) % 6];
  30     res.g = CUBE_STEPS[(xcolor / 6) % 6];
  31     res.b = CUBE_STEPS[xcolor % 6];
  32   } else if (232 <= xcolor && xcolor <= 255) {
  33     res.r = res.g = res.b = 8 + (xcolor - 232) * 0x0A;
  34   }
  35   return res;
  36 }
  37
  38 int init()
  39 {
  40   int c;
  41   for (c = 0; c < 256; c++) {
  42     COLOR_TABLE[c] = ansi_to_rgb(c);
  43   }
  44   return 0;
  45 }
  46
  47 int rgb_to_ansi(int r, int g, int b)
  48 {
  49   int best_match = 0;
  50   int smallest_distance = 1000000000;
  51   int c, d;
  52   for (c = 16; c < 256; c++) {
  53     d = (COLOR_TABLE[c].r - r)*(COLOR_TABLE[c].r - r) +
  54         (COLOR_TABLE[c].g - g)*(COLOR_TABLE[c].g - g) +
  55         (COLOR_TABLE[c].b - b)*(COLOR_TABLE[c].b - b);
  56     if (d < smallest_distance) {
  57       smallest_distance = d;
  58       best_match = c;
  59     }
  60   }
  61   return best_match;
  62 }