feat: add ColorHelpers class, various tools to manipulate HSV colors

Dalamud/Interface/ColorHelpers.cs

@@ -0,0 +1,261 @@
+using System;
+using System.Numerics;
+
+namespace Dalamud.Interface;
+
+/// <summary>
+/// Class containing various methods for manipulating colors.
+/// </summary>
+public static class ColorHelpers
+{
+    /// <summary>
+    /// Pack a vector4 color into a uint for use in ImGui APIs.
+    /// </summary>
+    /// <param name="color">The color to pack.</param>
+    /// <returns>The packed color.</returns>
+    public static uint RgbaVector4ToUint(Vector4 color)
+    {
+        var r = (byte)(color.X * 255);
+        var g = (byte)(color.Y * 255);
+        var b = (byte)(color.Z * 255);
+        var a = (byte)(color.W * 255);
+
+        return (uint)((a << 24) | (b << 16) | (g << 8) | r);
+    }
+    
+    /// <summary>
+    /// Convert a RGBA color in the range of 0.f to 1.f to a uint.
+    /// </summary>
+    /// <param name="color">The color to pack.</param>
+    /// <returns>The packed color.</returns>
+    public static Vector4 RgbaUintToVector4(uint color)
+    {
+        var r = (color & 0x000000FF) / 255f;
+        var g = ((color & 0x0000FF00) >> 8) / 255f;
+        var b = ((color & 0x00FF0000) >> 16) / 255f;
+        var a = ((color & 0xFF000000) >> 24) / 255f;
+
+        return new Vector4(r, g, b, a);
+    }
+    
+    /// <summary>
+    /// Convert a RGBA color in the range of 0.f to 1.f to a HSV color.
+    /// </summary>
+    /// <param name="color">The color to convert.</param>
+    /// <returns>The color in a HSV representation.</returns>
+    public static HsvaColor RgbaToHsv(Vector4 color)
+    {
+        var r = color.X;
+        var g = color.Y;
+        var b = color.Z;
+
+        var max = Math.Max(r, Math.Max(g, b));
+        var min = Math.Min(r, Math.Min(g, b));
+
+        var h = max;
+        var s = max;
+        var v = max;
+
+        var d = max - min;
+        s = max == 0 ? 0 : d / max;
+
+        if (max == min)
+        {
+            h = 0; // achromatic
+        }
+        else
+        {
+            if (max == r)
+            {
+                h = ((g - b) / d) + (g < b ? 6 : 0);
+            }
+            else if (max == g)
+            {
+                h = ((b - r) / d) + 2;
+            }
+            else if (max == b)
+            {
+                h = ((r - g) / d) + 4;
+            }
+
+            h /= 6;
+        }
+
+        return new HsvaColor(h, s, v, color.W);
+    }
+
+    /// <summary>
+    /// Convert a HSV color to a RGBA color in the range of 0.f to 1.f.
+    /// </summary>
+    /// <param name="hsv">The color to convert.</param>
+    /// <returns>The RGB color.</returns>
+    public static Vector4 HsvToRgb(HsvaColor hsv)
+    {
+        var h = hsv.H;
+        var s = hsv.S;
+        var v = hsv.V;
+
+        var r = 0f;
+        var g = 0f;
+        var b = 0f;
+
+        var i = (int)Math.Floor(h * 6);
+        var f = (h * 6) - i;
+        var p = v * (1 - s);
+        var q = v * (1 - (f * s));
+        var t = v * (1 - ((1 - f) * s));
+
+        switch (i % 6)
+        {
+            case 0:
+                r = v;
+                g = t;
+                b = p;
+                break;
+
+            case 1:
+                r = q;
+                g = v;
+                b = p;
+                break;
+
+            case 2:
+                r = p;
+                g = v;
+                b = t;
+                break;
+
+            case 3:
+                r = p;
+                g = q;
+                b = v;
+                break;
+
+            case 4:
+                r = t;
+                g = p;
+                b = v;
+                break;
+
+            case 5:
+                r = v;
+                g = p;
+                b = q;
+                break;
+        }
+
+        return new Vector4(r, g, b, hsv.A);
+    }
+    
+    /// <summary>
+    /// Lighten a color.
+    /// </summary>
+    /// <param name="color">The color to lighten.</param>
+    /// <param name="amount">The amount to lighten.</param>
+    /// <returns>The lightened color.</returns>
+    public static Vector4 Lighten(this Vector4 color, float amount)
+    {
+        var hsv = RgbaToHsv(color);
+        hsv.V += amount;
+        return HsvToRgb(hsv);
+    }
+    
+    /// <summary>
+    /// Lighten a color.
+    /// </summary>
+    /// <param name="color">The color to lighten.</param>
+    /// <param name="amount">The amount to lighten.</param>
+    /// <returns>The lightened color.</returns>
+    public static uint Lighten(uint color, float amount)
+        => RgbaVector4ToUint(Lighten(RgbaUintToVector4(color), amount));
+    
+    /// <summary>
+    /// Darken a color.
+    /// </summary>
+    /// <param name="color">The color to lighten.</param>
+    /// <param name="amount">The amount to lighten.</param>
+    /// <returns>The darkened color.</returns>
+    public static Vector4 Darken(this Vector4 color, float amount)
+    {
+        var hsv = RgbaToHsv(color);
+        hsv.V -= amount;
+        return HsvToRgb(hsv);
+    }
+    
+    /// <summary>
+    /// Darken a color.
+    /// </summary>
+    /// <param name="color">The color to lighten.</param>
+    /// <param name="amount">The amount to lighten.</param>
+    /// <returns>The darkened color.</returns>
+    public static uint Darken(uint color, float amount)
+        => RgbaVector4ToUint(Darken(RgbaUintToVector4(color), amount));
+    
+    /// <summary>
+    /// Saturate a color.
+    /// </summary>
+    /// <param name="color">The color to lighten.</param>
+    /// <param name="amount">The amount to lighten.</param>
+    /// <returns>The saturated color.</returns>
+    public static Vector4 Saturate(this Vector4 color, float amount)
+    {
+        var hsv = RgbaToHsv(color);
+        hsv.S += amount;
+        return HsvToRgb(hsv);
+    }
+    
+    /// <summary>
+    /// Saturate a color.
+    /// </summary>
+    /// <param name="color">The color to lighten.</param>
+    /// <param name="amount">The amount to lighten.</param>
+    /// <returns>The saturated color.</returns>
+    public static uint Saturate(uint color, float amount)
+        => RgbaVector4ToUint(Saturate(RgbaUintToVector4(color), amount));
+    
+    /// <summary>
+    /// Desaturate a color.
+    /// </summary>
+    /// <param name="color">The color to lighten.</param>
+    /// <param name="amount">The amount to lighten.</param>
+    /// <returns>The desaturated color.</returns>
+    public static Vector4 Desaturate(this Vector4 color, float amount)
+    {
+        var hsv = RgbaToHsv(color);
+        hsv.S -= amount;
+        return HsvToRgb(hsv);
+    }
+    
+    /// <summary>
+    /// Desaturate a color.
+    /// </summary>
+    /// <param name="color">The color to lighten.</param>
+    /// <param name="amount">The amount to lighten.</param>
+    /// <returns>The desaturated color.</returns>
+    public static uint Desaturate(uint color, float amount)
+        => RgbaVector4ToUint(Desaturate(RgbaUintToVector4(color), amount));
+    
+    /// <summary>
+    /// Fade a color.
+    /// </summary>
+    /// <param name="color">The color to lighten.</param>
+    /// <param name="amount">The amount to lighten.</param>
+    /// <returns>The faded color.</returns>
+    public static Vector4 Fade(this Vector4 color, float amount)
+    {
+        var hsv = RgbaToHsv(color);
+        hsv.A -= amount;
+        return HsvToRgb(hsv);
+    }
+    
+    /// <summary>
+    /// Fade a color.
+    /// </summary>
+    /// <param name="color">The color to lighten.</param>
+    /// <param name="amount">The amount to lighten.</param>
+    /// <returns>The faded color.</returns>
+    public static uint Fade(uint color, float amount)
+        => RgbaVector4ToUint(Fade(RgbaUintToVector4(color), amount));
+    
+    public record struct HsvaColor(float H, float S, float V, float A);
+}