diff options
Diffstat (limited to '')
| -rw-r--r-- | blackbody.c | 186 |
1 files changed, 78 insertions, 108 deletions
diff --git a/blackbody.c b/blackbody.c index 104e7da..9dfe1a8 100644 --- a/blackbody.c +++ b/blackbody.c @@ -4,173 +4,143 @@ # pragma GCC diagnostic ignored "-Wunsuffixed-float-constants" #endif - #ifndef LIBRED_COMPILING_PARSER #include "libred.h" -#include "macros.h" -#include <math.h> #include <errno.h> -#include <fcntl.h> - - - -/** - * The file descriptor to the colour lookup table. - */ -int libred_fd = -1; - +#include <math.h> +#include <stddef.h> -/** - * 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(); - libred_fd = open(SYSDEPRESDIR "/" PACKAGE "/10deg", O_RDONLY); - return libred_fd < 0 ? -1 : 0; -} +struct xy {double x, y;}; +struct rgb {double r, g, b;}; +static struct xy xy_table[] = { +#include "10deg-xy.i" +}; -/** - * Call this when the process will not - * longer make calls to `libred_get_colour`. - */ -void -libred_term_colour(void) -{ - if (libred_fd >= 0) - close(libred_fd), libred_fd = -1; -} +static struct rgb rgb_table[] = { +#include "10deg-rgb.i" +}; #endif /** - * Convert from CIE xyY to [0, 1] sRGB. + * Convert from CIE xyY to [0, 1] sRGB * - * @param x The 'x' component. - * @param y The 'y' component. - * @param Y The 'Y' component. - * @param r Output parameter for the “red” value. - * (Seriously, sRGB red is orange, just look at it fullscreen.) - * @param g Output parameter for the green value. - * @param b Output parameter for the blue value. + * @param x The 'x' component + * @param y The 'y' component + * @param Y The 'Y' component + * @param r Output parameter for the “red” value + * (Seriously, sRGB red is orange, just look at it fullscreen) + * @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) { #define SRGB(C) (((C) <= 0.0031308) ? (12.92 * (C)) : ((1.0 + 0.055) * pow((C), 1.0 / 2.4) - 0.055)) - double X, Z; + double X, Z, max; #if __GNUC__ # pragma GCC diagnostic push # pragma GCC diagnostic ignored "-Wfloat-equal" #endif - /* Convert CIE xyY to CIE XYZ. */ + /* 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)); #if __GNUC__ # pragma GCC diagnostic pop #endif - /* Convert CIE XYZ to [0, 1] linear RGB. (ciexyz_to_linear) */ + /* 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. */ + /* Convert [0, 1] linear RGB to [0, 1] sRGB */ SRGB(*r), SRGB(*g), SRGB(*b); + + /* Adjust colours for use */ + max = fmax(fmax(fabs(*r), fabs(*g)), fabs(*b)); +#if __GNUC__ +# pragma GCC diagnostic push +# pragma GCC diagnostic ignored "-Wfloat-equal" +#endif + if (max != 0.0) *r /= max, *g /= max, *b /= max; +#if __GNUC__ +# pragma GCC diagnostic pop +#endif + *r = *r > 0.0 ? *r : 0.0; + *g = *g > 0.0 ? *g : 0.0; + *b = *b > 0.0 ? *b : 0.0; } #ifndef LIBRED_COMPILING_PARSER - /** * Perform linear interpolation (considered very good) * between the CIE xyY values for two colour temperatures * and convert the result to sRGB. The two colours should * be the closest below the desired colour temperature, - * and the closest above the desired colour temperature. + * and the closest above the desired colour temperature * - * @param x1 The 'x' component for the low colour. - * @param y1 The 'y' component for the low colour. - * @param x2 The 'x' component for the high colour. - * @param y2 The 'y' component for the high colour. - * @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. + * @param x1 The 'x' component for the low colour + * @param y1 The 'y' component for the low colour + * @param x2 The 'x' component for the high colour + * @param y2 The 'y' component for the high colour + * @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 */ static void interpolate(double x1, double y1, double x2, double y2, double temp, double *r, double *g, double *b) { - double weight = fmod(temp, (double)LIBRED_DELTA_TEMPERATURE) / (double)LIBRED_DELTA_TEMPERATURE; + double weight = fmod(temp - (LIBRED_LOWEST_TEMPERATURE % LIBRED_DELTA_TEMPERATURE), + (double)LIBRED_DELTA_TEMPERATURE) / (double)LIBRED_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 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. + * Get the [0, 1] sRGB values of a colour temperature * - * @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). + * @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 EDOM The selected temperature is below 1000 K */ 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 > LIBRED_HIGHEST_TEMPERATURE) temp = LIBRED_HIGHEST_TEMPERATURE; - /* Things do not glow below 1000 K. Yes, fire is hot! */ - if (temp < LIBRED_LOWEST_TEMPERATURE) t ((errno = EDOM)); - - /* Read table. */ - offset = ((off_t)temp - LIBRED_LOWEST_TEMPERATURE) / LIBRED_DELTA_TEMPERATURE; - offset *= (off_t)(sizeof(values) / 2); - errno = EOVERFLOW; xpread(libred_fd, values, sizeof(values), offset); - - /* Get colour. */ - if (temp % LIBRED_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 __GNUC__ -# pragma GCC diagnostic push -# pragma GCC diagnostic ignored "-Wfloat-equal" -#endif - if (max != 0.0) *r /= max, *g /= max, *b /= max; -#if __GNUC__ -# pragma GCC diagnostic pop -#endif - *r = *r > 0.0 ? *r : 0.0; - *g = *g > 0.0 ? *g : 0.0; - *b = *b > 0.0 ? *b : 0.0; + double x1, y1, x2, y2; + size_t i; + + if (temp > LIBRED_HIGHEST_TEMPERATURE) + temp = LIBRED_HIGHEST_TEMPERATURE; + + if (temp < LIBRED_LOWEST_TEMPERATURE) { + errno = EDOM; + return -1; + } + + if (temp % LIBRED_DELTA_TEMPERATURE) { /* TODO make optional */ + i = (temp - LIBRED_LOWEST_TEMPERATURE) / LIBRED_DELTA_TEMPERATURE; + x1 = xy_table[i].x; + y1 = xy_table[i].y; + x2 = xy_table[i + 1].x; + y2 = xy_table[i + 1].y; + interpolate(x1, y1, x2, y2, (double)temp, r, g, b); + } else { + i = (temp - LIBRED_LOWEST_TEMPERATURE) / LIBRED_DELTA_TEMPERATURE; + *r = rgb_table[i].r; + *g = rgb_table[i].g; + *b = rgb_table[i].b; + } return 0; -fail: - return -1; } #endif |