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.
22static 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*/
39static inline uint32
40color_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
57static inline uint8
58FindClosestColor(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
75static inline rgb_color
76InvertColor(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
94static void
95FillColorMap(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*/
120void
121InitializeColorMap()
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*/
130const rgb_color *
131SystemPalette()
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*/
140const color_map *
141SystemColorMap()
142{
143	return &sColorMap;
144}
145