src/servers/app/SystemPalette.cpp

   1 /*
   2  * Copyright 2001-2006, Haiku.
   3  * Distributed under the terms of the MIT License.
   4  *
   5  * Authors:
   6  *              DarkWyrm <bpmagic@columbus.rr.com>
   7  *              Stefano Ceccherini (burton666@libero.it)
   8  */
   9
  10 //! Methods to initialize and get the system color_map.
  11
  12
  13 #include "SystemPalette.h"
  14
  15 #include <stdio.h>
  16 #include <string.h>
  17
  18 #include <Palette.h>
  19
  20 // TODO: BWindowScreen has a method to set the palette.
  21 // maybe we should have a lock to protect this variable.
  22 static color_map sColorMap;
  23
  24
  25 // color_distance
  26 /*!     \brief Returns the "distance" between two RGB colors.
  27
  28         This functions defines an metric on the RGB color space. The distance
  29         between two colors is 0, if and only if the colors are equal.
  30
  31         \param red1 Red component of the first color.
  32         \param green1 Green component of the first color.
  33         \param blue1 Blue component of the first color.
  34         \param red2 Red component of the second color.
  35         \param green2 Green component of the second color.
  36         \param blue2 Blue component of the second color.
  37         \return The distance between the given colors.
  38 */
  39 static inline uint32
  40 color_distance(uint8 red1, uint8 green1, uint8 blue1,
  41                            uint8 red2, uint8 green2, uint8 blue2)
  42 {
  43         int rd = (int)red1 - (int)red2;
  44         int gd = (int)green1 - (int)green2;
  45         int bd = (int)blue1 - (int)blue2;
  46
  47         // distance according to psycho-visual tests
  48         // algorithm taken from here:
  49         // http://www.stud.uni-hannover.de/~michaelt/juggle/Algorithms.pdf
  50         int rmean = ((int)red1 + (int)red2) / 2;
  51         return (((512 + rmean) * rd * rd) >> 8)
  52                         + 4 * gd * gd
  53                         + (((767 - rmean) * bd * bd) >> 8);
  54 }
  55
  56
  57 static inline uint8
  58 FindClosestColor(const rgb_color &color, const rgb_color *palette)
  59 {
  60         uint8 closestIndex = 0;
  61         unsigned closestDistance = UINT_MAX;
  62         for (int32 i = 0; i < 256; i++) {
  63                 const rgb_color &c = palette[i];
  64                 unsigned distance = color_distance(color.red, color.green, color.blue,
  65                                                                                    c.red, c.green, c.blue);
  66                 if (distance < closestDistance) {
  67                         closestIndex = (uint8)i;
  68                         closestDistance = distance;
  69                 }
  70         }
  71         return closestIndex;
  72 }
  73
  74
  75 static inline rgb_color
  76 InvertColor(const rgb_color &color)
  77 {
  78         // For some reason, Inverting (255, 255, 255) on beos
  79         // results in the same color.
  80         if (color.red == 255 && color.green == 255
  81                 && color.blue == 255)
  82                 return color;
  83
  84         rgb_color inverted;
  85         inverted.red = 255 - color.red;
  86         inverted.green = 255 - color.green;
  87         inverted.blue = 255 - color.blue;
  88         inverted.alpha = 255;
  89
  90         return inverted;
  91 }
  92
  93
  94 static void
  95 FillColorMap(const rgb_color *palette, color_map *map)
  96 {
  97         memcpy(map->color_list, palette, sizeof(map->color_list));
  98
  99         // init index map
 100         for (int32 color = 0; color < 32768; color++) {
 101                 // get components
 102                 rgb_color rgbColor;
 103                 rgbColor.red = (color & 0x7c00) >> 7;
 104                 rgbColor.green = (color & 0x3e0) >> 2;
 105                 rgbColor.blue = (color & 0x1f) << 3;
 106
 107                 map->index_map[color] = FindClosestColor(rgbColor, palette);
 108         }
 109
 110         // init inversion map
 111         for (int32 index = 0; index < 256; index++) {
 112                 rgb_color inverted = InvertColor(map->color_list[index]);
 113                 map->inversion_map[index] = FindClosestColor(inverted, palette);
 114         }
 115 }
 116
 117
 118 /*!     \brief Initializes the system color_map.
 119 */
 120 void
 121 InitializeColorMap()
 122 {
 123         FillColorMap(kSystemPalette, &sColorMap);
 124 }
 125
 126
 127 /*!     \brief Returns a pointer to the system palette.
 128         \return A pointer to the system palette.
 129 */
 130 const rgb_color *
 131 SystemPalette()
 132 {
 133         return sColorMap.color_list;
 134 }
 135
 136
 137 /*!     \brief Returns a pointer to the system color_map structure.
 138         \return A pointer to the system color_map.
 139 */
 140 const color_map *
 141 SystemColorMap()
 142 {
 143         return &sColorMap;
 144 }