huehuehue/HueUWP/ColorUtil.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Windows.UI;

namespace HueUWP
{
    public static class ColorUtil
    {

        public static Color getColor(Light light)
        {
            double hue = ((double)light.Hue * 360.0f) / 65535.0f;
            double sat = (double)light.Saturation / 255.0f;
            double val = (double)light.Brightness/ 255.0f;

            int r, g, b;
            HsvToRgb(hue, sat, val, out r, out g, out b);
            return Color.FromArgb(255, Convert.ToByte(r), Convert.ToByte(g), Convert.ToByte(b));
        }

        public static void RGBtoHSV(double r, double g, double b, out double h, out double s, out double v)
        {
            double min, max, delta;

            min = Math.Min(r, Math.Min(g, b));
            max = Math.Max(r, Math.Max(g, b));

            v = max;				// v
            delta = max - min;

            if (max != 0)
                s = delta / max;		// s
            else
            {
                // r = g = b = 0		// s = 0, v is undefined
                s = 0;
                h = -1;
                return;
            }

            if (r == max)
                h = (g - b) / delta;		// between yellow & magenta
            else if (g == max)
                h = 2 + (b - r) / delta;	// between cyan & yellow
            else
                h = 4 + (r - g) / delta;	// between magenta & cyan

            h *= 60;				// degrees

            if (h < 0)
                h += 360;
        }

        private static void HsvToRgb(double h, double S, double V, out int r, out int g, out int b)
        {
            double H = h;
            while (H < 0)
            {
                H += 360;
            }
            while (H >= 360)
            {
                H -= 360;
            }

            double R, G, B;
            if (V <= 0)
                R = G = B = 0;
            else if (S <= 0)
                R = G = B = V;
            else
            {
                double hf = H / 60.0;
                int i = (int)Math.Floor(hf);
                double f = hf - i;
                double pv = V * (1 - S);
                double qv = V * (1 - S * f);
                double tv = V * (1 - S * (1 - f));
                switch (i)
                {
                    // Red is the dominant color
                    case 0:
                        R = V;
                        G = tv;
                        B = pv;
                        break;
                    // Green is the dominant color
                    case 1:
                        R = qv;
                        G = V;
                        B = pv;
                        break;
                    case 2:
                        R = pv;
                        G = V;
                        B = tv;
                        break;
                    // Blue is the dominant color
                    case 3:
                        R = pv;
                        G = qv;
                        B = V;
                        break;
                    case 4:
                        R = tv;
                        G = pv;
                        B = V;
                        break;
                    // Red is the dominant color
                    case 5:
                        R = V;
                        G = pv;
                        B = qv;
                        break;
                    // Just in case we overshoot on our math by a little, we put these here. Since its a switch it won't slow us down at all to put these here.
                    case 6:
                        R = V;
                        G = tv;
                        B = pv;
                        break;
                    case -1:
                        R = V;
                        G = pv;
                        B = qv;
                        break;
                    // The color is not defined, we should throw an error.
                    default:
                        //LFATAL("i Value error in Pixel conversion, Value is %d", i);
                        R = G = B = V; // Just pretend its black/white
                        break;
                }
            }

            r = Clamp((int)(R * 255.0));
            g = Clamp((int)(G * 255.0));
            b = Clamp((int)(B * 255.0));
        }

        private static int Clamp(int i)
        {
            if (i < 0) return 0;
            if (i > 255) return 255;
            return i;
        }

        public static Color HsvToRgb(double hue, double sat, double val)
        {

            double h = ((double)hue * 360.0f) / 65535.0f;
            double s = (double)sat / 255.0f;
            double v = (double)val / 255.0f;

            int hi = (int)Math.Floor(h / 60.0) % 6;
            double f = (h / 60.0) - Math.Floor(h / 60.0);

            double p = v * (1.0 - s);
            double q = v * (1.0 - (f * s));
            double t = v * (1.0 - ((1.0 - f) * s));

            Color ret;

            switch (hi)
            {
                case 0:
                    ret = GetRgb(v, t, p);
                    break;
                case 1:
                    ret = GetRgb(q, v, p);
                    break;
                case 2:
                    ret = GetRgb(p, v, t);
                    break;
                case 3:
                    ret = GetRgb(p, q, v);
                    break;
                case 4:
                    ret = GetRgb(t, p, v);
                    break;
                case 5:
                    ret = GetRgb(v, p, q);
                    break;
                default:
                    ret = Color.FromArgb(0xFF, 0x00, 0x00, 0x00);
                    break;
            }
            return ret;
        }

        public static Color GetRgb(double r, double g, double b)
        {
            return Color.FromArgb(255, (byte)(r * 255.0), (byte)(g * 255.0), (byte)(b * 255.0));
        }
    }
}