1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
|
/**
* Copyright © 2016 Mattias Andrée <maandree@member.fsf.org>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef LIBRED_H
#define LIBRED_H
/**
* Approximate apparent size of the Sun in degrees.
*/
#define LIBRED_SOLAR_APPARENT_RADIUS (32.0 / 60.0)
/**
* The Sun's elevation at sunset and sunrise, measured in degrees.
*/
#define LIBRED_SOLAR_ELEVATION_SUNSET_SUNRISE (0.0)
/**
* The Sun's elevation at civil dusk and civil dawn, measured in degrees.
*/
#define LIBRED_SOLAR_ELEVATION_CIVIL_DUSK_DAWN (-6.0)
/**
* The Sun's elevation at nautical dusk and nautical dawn, measured in degrees.
*/
#define LIBRED_SOLAR_ELEVATION_NAUTICAL_DUSK_DAWN (-12.0)
/**
* The Sun's elevation at astronomical dusk and astronomical dawn, measured in degrees.
*/
#define LIBRED_SOLAR_ELEVATION_ASTRONOMICAL_DUSK_DAWN (-18.0)
/**
* Test whether it is twilight.
*
* @param ELEV:double The current elevation.
* @return 1 if is twilight, 0 otherwise.
*/
#define LIBRED_IS_TWILIGHT(ELEV) ((-18.0 <= (ELEV)) && ((ELEV) <= 0.0))
/**
* Test whether it is civil twilight.
*
* @param ELEV:double The current elevation.
* @return 1 if is civil twilight, 0 otherwise.
*/
#define LIBRED_IS_CIVIL_TWILIGHT(ELEV) ((-6.0 <= (ELEV)) && ((ELEV) <= 0.0))
/**
* Test whether it is nautical twilight.
*
* @param ELEV:double The current elevation.
* @return 1 if is nautical twilight, 0 otherwise.
*/
#define LIBRED_IS_NAUTICAL_TWILIGHT(ELEV) ((-12.0 <= (ELEV)) && ((ELEV) <= -6.0))
/**
* Test whether it is astronomical twilight.
*
* @param ELEV:double The current elevation.
* @return 1 if is astronomical twilight, 0 otherwise.
*/
#define LIBRED_IS_ASTRONOMICAL_TWILIGHT(ELEV) ((-18.0 <= (ELEV)) && ((ELEV) <= -12.0))
/**
* Calculates the Sun's elevation as apparent
* from a geographical position.
*
* @param latitude The latitude in degrees northwards from
* the equator, negative for southwards.
* @param longitude The longitude in degrees eastwards from
* Greenwich, negative for westwards.
* @return The Sun's apparent elevation as seen, right now,
* from the specified position, measured in degrees.
*
* @throws 0 On success.
* @throws Any error specified for clock_gettime(3) on error.
*/
double libred_solar_elevation(double, double);
/**
* Exit if time the is before year 0 in J2000.
*
* @return 0 on success, -1 on error.
*/
int libred_check_timetravel(void);
/**
* The highest colour temperature in the table.
*/
#define LIBRED_HIGHEST_TEMPERATURE 40000
/**
* The lowest colour temperature in the table.
*/
#define LIBRED_LOWEST_TEMPERATURE 1000
/**
* The temperature difference between the colours in the table.
* Note, `libred_get_colour` will make interpolation for colours
* that are not in the table.
*/
#define LIBRED_DELTA_TEMPERATURE 100
/**
* The file descriptor to the colour lookup table.
* -1 if none is open.
*/
extern int libred_fd;
/**
* Iff this macro is define `libred_fd` is available.
*/
#define LIBRED_HAVE_FD 1
/**
* This function must be called, once,
* before calling `libred_get_colour`.
*
* @return 0 on success, -1 on error.
*
* @throws Any error specified for `open(3)`.
*/
int libred_init_colour(void);
/**
* Call this when the process will not
* longer make calls to `libred_get_colour`.
*/
void libred_term_colour(void);
/**
* Get the [0, 1] sRGB values of a colour temperature.
*
* @param temp The desired colour temperature.
* @param r Output parameter for the “red” value.
* @param g Output parameter for the green value.
* @param b Output parameter for the blue value.
* @return 0 on succeess, -1 on error.
*
* @throws EOVERFLOW The file did not have the expected size.
* @throws EDOM The selected temperature is below 1000 K.
* @throws Any error specified for pread(3).
*/
int libred_get_colour(long int, double*, double*, double*);
#endif
|
