File content as of revision 2:9447404f2d16:

#include <math.h>
#include "Colors.h"

void HSBtoRGB(float hue, float saturation, float brightness, uint8_t *pr, uint8_t *pg, uint8_t *pb)
{
    uint8_t r = 0, g = 0, b = 0;
    if (saturation == 0) {
        r = g = b = (uint8_t) (brightness * 255.0f + 0.5f);
    } else {
        float h = (hue - (float)floor(hue)) * 6.0f;
        float f = h - (float)floor(h);
        float p = brightness * (1.0f - saturation);
        float q = brightness * (1.0f - saturation * f);
        float t = brightness * (1.0f - (saturation * (1.0f - f)));
        switch ((int) h) {
            case 0:
                r = (int) (brightness * 255.0f + 0.5f);
                g = (int) (t * 255.0f + 0.5f);
                b = (int) (p * 255.0f + 0.5f);
                break;
            case 1:
                r = (int) (q * 255.0f + 0.5f);
                g = (int) (brightness * 255.0f + 0.5f);
                b = (int) (p * 255.0f + 0.5f);
                break;
            case 2:
                r = (int) (p * 255.0f + 0.5f);
                g = (int) (brightness * 255.0f + 0.5f);
                b = (int) (t * 255.0f + 0.5f);
                break;
            case 3:
                r = (int) (p * 255.0f + 0.5f);
                g = (int) (q * 255.0f + 0.5f);
                b = (int) (brightness * 255.0f + 0.5f);
                break;
            case 4:
                r = (int) (t * 255.0f + 0.5f);
                g = (int) (p * 255.0f + 0.5f);
                b = (int) (brightness * 255.0f + 0.5f);
                break;
            case 5:
                r = (int) (brightness * 255.0f + 0.5f);
                g = (int) (p * 255.0f + 0.5f);
                b = (int) (q * 255.0f + 0.5f);
                break;
        }
    }
    *pr = r;
    *pg = g;
    *pb = b;
}

float* RGBtoHSB(uint8_t r, uint8_t g, uint8_t b, float* hsbvals)
{
    float hue, saturation, brightness;
    if (!hsbvals) {
        hsbvals = new float[3];
    }
    uint8_t cmax = (r > g) ? r : g;
    if (b > cmax) cmax = b;
    uint8_t cmin = (r < g) ? r : g;
    if (b < cmin) cmin = b;

    brightness = ((float) cmax) / 255.0f;
    if (cmax != 0)
        saturation = ((float) (cmax - cmin)) / ((float) cmax);
    else
        saturation = 0;
    if (saturation == 0)
        hue = 0;
    else {
        float redc = ((float) (cmax - r)) / ((float) (cmax - cmin));
        float greenc = ((float) (cmax - g)) / ((float) (cmax - cmin));
        float bluec = ((float) (cmax - b)) / ((float) (cmax - cmin));
        if (r == cmax)
            hue = bluec - greenc;
        else if (g == cmax)
            hue = 2.0f + redc - bluec;
        else
            hue = 4.0f + greenc - redc;
        hue = hue / 6.0f;
        if (hue < 0)
            hue = hue + 1.0f;
    }
    hsbvals[0] = hue;
    hsbvals[1] = saturation;
    hsbvals[2] = brightness;
    return hsbvals;
}