ryujinx/src/Ryujinx.Common/Utilities/Rainbow.cs

using Gommon;
using Ryujinx.Common.Helper;
using System;
using System.Drawing;
using System.Threading;
using System.Threading.Tasks;

namespace Ryujinx.Common.Utilities
{
    public static class Rainbow
    {
        public static bool CyclingEnabled { get; set; }

        public static void Enable()
        {
            if (!CyclingEnabled)
            {
                CyclingEnabled = true;
                Executor.ExecuteBackgroundAsync(async () =>
                {
                    while (CyclingEnabled)
                    {
                        await Task.Delay(20);
                        Tick();
                    }
                });
            }
        }

        public static void Disable()
        {
            CyclingEnabled = false;
        }


        public static float Speed { get; set; } = 1;

        private static readonly Lock _lock = new();

        private static Color _color = Color.Blue;

        public static ref Color Color
        {
            get
            {
                lock (_lock)
                {
                    return ref _color;
                }
            }
        }

        public static void Tick()
        {
            lock (_lock)
            {
                _color = HsbToRgb((_color.GetHue() + Speed) / 360);

                _updatedHandler.Call(ref _color);
            }
        }

        public static void Reset()
        {
            _updatedHandler.Clear();

            lock (_lock)
                _color = Color.Blue;
        }

        public static event RefEvent<Color>.Handler Updated
        {
            add => _updatedHandler.Add(value);
            remove => _updatedHandler.Remove(value);
        }

        private static readonly RefEvent<Color> _updatedHandler = new();

        private static Color HsbToRgb(float hue, float saturation = 1, float brightness = 1)
        {
            int r = 0, g = 0, b = 0;
            if (saturation == 0)
            {
                r = g = b = (int)(brightness * 255.0f + 0.5f);
            }
            else
            {
                float h = (hue - (float)Math.Floor(hue)) * 6.0f;
                float f = h - (float)Math.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;
                }
            }

            return Color.FromArgb(Convert.ToByte(255), Convert.ToByte(r), Convert.ToByte(g), Convert.ToByte(b));
        }
    }
}