Add some refactoring of data, Stains and STM files.

Penumbra.GameData/Structs/Stain.cs

@@ -0,0 +1,52 @@
+using Dalamud.Utility;
+
+namespace Penumbra.GameData.Structs;
+
+// A wrapper for the clothing dyes the game provides with their RGBA color value, game ID, unmodified color value and name.
+public readonly struct Stain
+{
+    // An empty stain with transparent color.
+    public static readonly Stain None = new("None");
+
+    public readonly string Name;
+    public readonly uint   RgbaColor;
+    public readonly byte   RowIndex;
+    public readonly bool   Gloss;
+
+    public byte R
+        => (byte)(RgbaColor & 0xFF);
+
+    public byte G
+        => (byte)((RgbaColor >> 8) & 0xFF);
+
+    public byte B
+        => (byte)((RgbaColor >> 16) & 0xFF);
+
+    public byte Intensity
+        => (byte)((1 + R + G + B) / 3);
+
+    // R and B need to be shuffled and Alpha set to max.
+    private static uint SeColorToRgba(uint color)
+        => ((color & 0xFF) << 16) | ((color >> 16) & 0xFF) | (color & 0xFF00) | 0xFF000000;
+
+    public Stain(Lumina.Excel.GeneratedSheets.Stain stain)
+        : this(stain.Name.ToDalamudString().ToString(), SeColorToRgba(stain.Color), (byte)stain.RowId, stain.Unknown4)
+    { }
+
+    internal Stain(string name, uint dye, byte index, bool gloss)
+    {
+        Name      = name;
+        RowIndex  = index;
+        Gloss     = gloss;
+        RgbaColor = dye;
+    }
+
+    // Only used by None.
+    private Stain(string name)
+    {
+        Name      = name;
+        RowIndex  = 0;
+        RgbaColor = 0;
+        Gloss     = false;
+    }
+}