diff options
Diffstat (limited to 'src/blackbody.c')
| -rw-r--r-- | src/blackbody.c | 145 |
1 files changed, 88 insertions, 57 deletions
diff --git a/src/blackbody.c b/src/blackbody.c index abe03a9..f45ead4 100644 --- a/src/blackbody.c +++ b/src/blackbody.c @@ -14,7 +14,7 @@ * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ -#include "blackbody.h" +#include "libred.h" #include "macros.h" #include <math.h> #include <errno.h> @@ -22,6 +22,40 @@ /** + * The file descriptor to the colour lookup table. + */ +static int 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) +{ + libred_term_colour(); + fd = open(SYSDEPRESDIR "/" PACKAGE "/10deg", O_RDONLY); + return fd < 0 ? -1 : 0; +} + + +/** + * Call this when the process will not + * longer make calls to `libred_get_colour`. + */ +void libred_term_colour(void) +{ + if (fd >= 0) + close(fd), fd = -1; +} + + +/** * Convert from CIE xyY to [0, 1] sRGB. * * @param x The 'x' component. @@ -32,23 +66,22 @@ * @param g Output parameter for the green value. * @param b Output parameter for the blue value. */ -static void -ciexyy_to_srgb(double x, double y, double Y, double *r, double *g, double *b) +static void ciexyy_to_srgb(double x, double y, double Y, double *r, double *g, double *b) { #define SRGB(C) (((C) <= 0.0031308) ? (12.92 * (C)) : ((1.0 + 0.055) * pow((C), 1.0 / 2.4) - 0.055)) - double X, Z; - - /* Convert CIE xyY to CIE XYZ. */ - X = Y * (y == 0.0 ? 0.0 : (x / y)); - Z = Y * (y == 0.0 ? 0.0 : ((1.0 - x - y) / y)); - - /* Convert CIE XYZ to [0, 1] linear RGB. (ciexyz_to_linear) */ - *r = ( 3.240450 * X) + (-1.537140 * Y) + (-0.4985320 * Z); - *g = (-0.969266 * X) + ( 1.876010 * Y) + ( 0.0415561 * Z); - *b = (0.0556434 * X) + (-0.204026 * Y) + ( 1.0572300 * Z); - - /* Convert [0, 1] linear RGB to [0, 1] sRGB. */ - SRGB(*r), SRGB(*g), SRGB(*b); + double X, Z; + + /* Convert CIE xyY to CIE XYZ. */ + X = Y * (y == 0.0 ? 0.0 : (x / y)); + Z = Y * (y == 0.0 ? 0.0 : ((1.0 - x - y) / y)); + + /* Convert CIE XYZ to [0, 1] linear RGB. (ciexyz_to_linear) */ + *r = ( 3.240450 * X) + (-1.537140 * Y) + (-0.4985320 * Z); + *g = (-0.969266 * X) + ( 1.876010 * Y) + ( 0.0415561 * Z); + *b = (0.0556434 * X) + (-0.204026 * Y) + ( 1.0572300 * Z); + + /* Convert [0, 1] linear RGB to [0, 1] sRGB. */ + SRGB(*r), SRGB(*g), SRGB(*b); } @@ -68,20 +101,18 @@ ciexyy_to_srgb(double x, double y, double Y, double *r, double *g, double *b) * @param g Output parameter for the green value. * @param b Output parameter for the blue value. */ -static void -interpolate(double x1, double y1, double x2, double y2, double temp, double *r, double *g, double *b) +static void interpolate(double x1, double y1, double x2, double y2, double temp, double *r, double *g, double *b) { - double weight = fmod(temp, (double)DELTA_TEMPERATURE) / (double)DELTA_TEMPERATURE; - double x = x1 * (1 - weight) + x2 * weight; - double y = y1 * (1 - weight) + y2 * weight; - ciexyy_to_srgb(x, y, 1.0, r, g, b); + double weight = fmod(temp, (double)DELTA_TEMPERATURE) / (double)DELTA_TEMPERATURE; + double x = x1 * (1 - weight) + x2 * weight; + double y = y1 * (1 - weight) + y2 * weight; + ciexyy_to_srgb(x, y, 1.0, r, g, b); } /** * Get the [0, 1] sRGB values of a colour temperature. * - * @param fd File descriptor for the colour table. * @param temp The desired colour temperature. * @param r Output parameter for the “red” value. * @param g Output parameter for the green value. @@ -90,41 +121,41 @@ interpolate(double x1, double y1, double x2, double y2, double temp, double *r, * * @throws 0 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 -get_colour(int fd, long int temp, double *r, double *g, double *b) +int libred_get_colour(long int temp, double *r, double *g, double *b) { - double values[10]; /* low:x,y,r,g,b + high:x,y,r,g,b */ - off_t offset; - double max; - - /* We do not have any values for above 40 000 K, but - * the differences will be unnoticeable, perhaps even - * unencodeable. */ - if (temp > HIGHEST_TEMPERATURE) temp = HIGHEST_TEMPERATURE; - /* Things do not glow below 1000 K. Yes, fire is hot! */ - if (temp < LOWEST_TEMPERATURE) t ((errno = EDOM)); - - /* Read table. */ - offset = ((off_t)temp - LOWEST_TEMPERATURE) / DELTA_TEMPERATURE; - offset *= (off_t)(sizeof(values) / 2); - errno = 0; xpread(fd, values, sizeof(values), offset); - - /* Get colour. */ - if (temp % DELTA_TEMPERATURE) - interpolate(values[0], values[1], values[6], values[7], (double)temp, r, g, b); - else - *r = values[2], *g = values[3], *b = values[4]; - - /* Adjust colours for use. */ - max = fmax(fmax(fabs(*r), fabs(*g)), fabs(*b)); - if (max != 0) *r /= max, *g /= max, *b /= max; - *r = *r > 0.0 ? *r : 0.0; - *g = *g > 0.0 ? *g : 0.0; - *b = *b > 0.0 ? *b : 0.0; - - return 0; -fail: - return -1; + double values[10]; /* low:x,y,r,g,b + high:x,y,r,g,b */ + off_t offset; + double max; + + /* We do not have any values for above 40 000 K, but + * the differences will be unnoticeable, perhaps even + * unencodeable. */ + if (temp > HIGHEST_TEMPERATURE) temp = HIGHEST_TEMPERATURE; + /* Things do not glow below 1000 K. Yes, fire is hot! */ + if (temp < LOWEST_TEMPERATURE) t ((errno = EDOM)); + + /* Read table. */ + offset = ((off_t)temp - LOWEST_TEMPERATURE) / DELTA_TEMPERATURE; + offset *= (off_t)(sizeof(values) / 2); + errno = 0; xpread(fd, values, sizeof(values), offset); + + /* Get colour. */ + if (temp % DELTA_TEMPERATURE) + interpolate(values[0], values[1], values[6], values[7], (double)temp, r, g, b); + else + *r = values[2], *g = values[3], *b = values[4]; + + /* Adjust colours for use. */ + max = fmax(fmax(fabs(*r), fabs(*g)), fabs(*b)); + if (max != 0) *r /= max, *g /= max, *b /= max; + *r = *r > 0.0 ? *r : 0.0; + *g = *g > 0.0 ? *g : 0.0; + *b = *b > 0.0 ? *b : 0.0; + + return 0; + fail: + return -1; } |