rom/graphics/color_support.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc:
   6     Lang: english
   7 */
   8
   9 #include <exec/types.h>
  10 #include <graphics/view.h>
  11
  12 /*
  13 ** In case the representation of colors in the ColorTable of the color map
  14 ** are changed then this here should be the place where to change the
  15 ** algorithms.
  16 */
  17
  18 ULONG color_distance(struct ColorMap * cm,
  19                      ULONG r,
  20                      ULONG g,
  21                      ULONG b,
  22                      ULONG index)
  23 {
  24     /*
  25     ** I am assuming 24 bit colors that are represented in the color map as
  26     ** follows:
  27     ** cm->ColorTable is a pointer to an array of UWORDs where every
  28     **     UWORD contains the most significant 4 bits of each color.
  29     ** cm->LowColorBits is a pointer to an array of UWORDs where every
  30     **     UWORD contains the least significant 4 bits of each color.
  31     ** for example a color r=12, g=34, b=56 would be represented as:
  32     **
  33     **   cm->ColorTable[x]   = 0x0135
  34     **   cm->LowColorBits[x] = 0x0246
  35     */
  36
  37     LONG dr,dg,db;
  38     UWORD c1,c2;
  39     c1 = ((UWORD *)cm->ColorTable)[index];
  40     c2 = ((UWORD *)cm->LowColorBits)[index];
  41
  42     dr = (LONG)(r >> (32-8)) - (LONG)(((c1 >> 4) & 0x00f0) | ((c2 >> 8) & 0x000f));
  43     dg = (LONG)(g >> (32-8)) - (LONG)(((c1 >> 0) & 0x00f0) | ((c2 >> 4) & 0x000f));
  44     db = (LONG)(b >> (32-8)) - (LONG)(((c1 << 4) & 0x00f0) | ((c2 >> 0) & 0x000f));
  45
  46     return dr*dr+dg*dg+db*db;
  47 }
  48
  49
  50 /*
  51 ** Test whether the entry in the color map equals the given
  52 ** color
  53 */
  54 BOOL color_equal(struct ColorMap * cm,
  55                  ULONG r,
  56                  ULONG g,
  57                  ULONG b,
  58                  ULONG index)
  59 {
  60     if ( ((UWORD *)cm->ColorTable)  [index] == (((r >> 20) & 0x0f00) |
  61                                                 ((g >> 24) & 0x00f0) |
  62                                                 ((b >> 28) & 0x000f))  &&
  63          ((UWORD *)cm->LowColorBits)[index] == (((r >> 16) & 0x0f00) |
  64                                                 ((g >> 20) & 0x00f0) |
  65                                                 ((b >> 24) & 0x000f)) )
  66         return TRUE;
  67     else
  68         return FALSE;
  69 }
  70
  71
  72 /*
  73 ** Set an entry in the color map
  74 */
  75 VOID color_set(struct ColorMap * cm,
  76                ULONG r,
  77                ULONG g,
  78                ULONG b,
  79                ULONG index)
  80 {
  81     ((UWORD *)cm->ColorTable)[index]   = ((r >> 20) & 0x0f00) |
  82                                          ((g >> 24) & 0x00f0) |
  83                                          ((b >> 28) & 0x000f);
  84
  85     ((UWORD *)cm->LowColorBits)[index] = ((r >> 16) & 0x0f00) |
  86                                          ((g >> 20) & 0x00f0) |
  87                                          ((b >> 24) & 0x000f);
  88 }
  89
  90
  91 VOID color_get(struct ColorMap *cm,
  92                 ULONG *r,
  93                 ULONG *g,
  94                 ULONG *b,
  95                 ULONG index)
  96 {
  97     UWORD hibits = ((UWORD *)cm->ColorTable)[index];
  98     UWORD lobits = ((UWORD *)cm->LowColorBits)[index];
  99
 100     ULONG red8   = ((hibits & 0x0f00) >> 4) | ((lobits & 0x0f00) >> 8);
 101     ULONG green8 = ((hibits & 0x00f0)     ) | ((lobits & 0x00f0) >> 4);
 102     ULONG blue8  = ((hibits & 0x000f) << 4) | ((lobits & 0x000f)     );
 103
 104     *r = red8   * 0x01010101;
 105     *g = green8 * 0x01010101;
 106     *b = blue8  * 0x01010101;
 107
 108 }
 109