qmk_firmware/quantum/color.c

/* Copyright 2017 Jason Williams
 *
 * 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 2 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 "color.h"
#include "led_tables.h"
#include "progmem.h"

RGB hsv_to_rgb(HSV hsv) {
    RGB      rgb;
    uint8_t  region, remainder, p, q, t;
    uint16_t h, s, v;

    if (hsv.s == 0) {
#ifdef USE_CIE1931_CURVE
        rgb.r = rgb.g = rgb.b = pgm_read_byte(&CIE1931_CURVE[hsv.v]);
#else
        rgb.r = hsv.v;
        rgb.g = hsv.v;
        rgb.b = hsv.v;
#endif
        return rgb;
    }

    h = hsv.h;
    s = hsv.s;
#ifdef USE_CIE1931_CURVE
    v = pgm_read_byte(&CIE1931_CURVE[hsv.v]);
#else
    v = hsv.v;
#endif

    region    = h * 6 / 255;
    remainder = (h * 2 - region * 85) * 3;

    p = (v * (255 - s)) >> 8;
    q = (v * (255 - ((s * remainder) >> 8))) >> 8;
    t = (v * (255 - ((s * (255 - remainder)) >> 8))) >> 8;

    switch (region) {
        case 6:
        case 0:
            rgb.r = v;
            rgb.g = t;
            rgb.b = p;
            break;
        case 1:
            rgb.r = q;
            rgb.g = v;
            rgb.b = p;
            break;
        case 2:
            rgb.r = p;
            rgb.g = v;
            rgb.b = t;
            break;
        case 3:
            rgb.r = p;
            rgb.g = q;
            rgb.b = v;
            break;
        case 4:
            rgb.r = t;
            rgb.g = p;
            rgb.b = v;
            break;
        default:
            rgb.r = v;
            rgb.g = p;
            rgb.b = q;
            break;
    }

    return rgb;
}