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Diffstat (limited to 'src/blackbody.c')
| -rw-r--r-- | src/blackbody.c | 130 |
1 files changed, 0 insertions, 130 deletions
diff --git a/src/blackbody.c b/src/blackbody.c deleted file mode 100644 index d393686..0000000 --- a/src/blackbody.c +++ /dev/null @@ -1,130 +0,0 @@ -/** - * 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/>. - */ -#include "blackbody.h" -#include "macros.h" -#include <math.h> -#include <errno.h> - - - -/** - * 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. - */ -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); -} - - -/** - * 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. - * - * @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)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. - * @param b Output parameter for the blue value. - * @return 0 on succeess, -1 on error. - * - * @throws 0 The file did not have the expected size. - * @throws EDOM The selected temperature is below 1000 K. - */ -int -get_colour(int fd, 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; -} - |