gaemstone/src/gaemstone.Client/Color.cs

using System;
using System.Diagnostics.CodeAnalysis;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using Silk.NET.Maths;

namespace gaemstone.Client;

[StructLayout(LayoutKind.Explicit)]
public readonly struct Color
	: IEquatable<Color>
{
	public static readonly Color Transparent = default;
	public static readonly Color Black = FromRGB(0x000000);
	public static readonly Color White = FromRGB(0xFFFFFF);

	[FieldOffset(0)]
	public readonly uint RGBA;

	[FieldOffset(0)]
	public readonly byte R;
	[FieldOffset(1)]
	public readonly byte G;
	[FieldOffset(2)]
	public readonly byte B;
	[FieldOffset(3)]
	public readonly byte A;

	private Color(uint rgba)
		{ Unsafe.SkipInit(out this); RGBA = rgba; }
	private Color(byte r, byte g, byte b, byte a)
		{ Unsafe.SkipInit(out this); R = r; G = g; B = b; A = a; }

	public static Color FromRGBA(uint rgba) => new(rgba);
	public static Color FromRGBA(byte r, byte g, byte b, byte a) => new(r, g, b, a);

	public static Color FromRGB(uint rgb) => new(rgb | 0xFF000000);
	public static Color FromRGB(byte r, byte g, byte b) => new(r, g, b, 0xFF);

	public static Color FromGrayscale(byte gray) => new(gray, gray, gray, 0xFF);
	public static Color FromGrayscale(byte gray, byte alpha) => new(gray, gray, gray, alpha);

	public bool Equals(Color other)
		=> RGBA == other.RGBA;
	public override bool Equals([NotNullWhen(true)] object? obj)
		=> (obj is Color color) && Equals(color);
	public override int GetHashCode()
		=> RGBA.GetHashCode();
	public override string? ToString()
		=> $"Color(0x{RGBA:X8})";

	public static bool operator ==(Color left, Color right) =>  left.Equals(right);
	public static bool operator !=(Color left, Color right) => !left.Equals(right);

	public static implicit operator System.Drawing.Color(Color color) => System.Drawing.Color.FromArgb(color.A, color.R, color.G, color.B);
	public static implicit operator Vector4D<float>(Color color) => new(color.R / 255F, color.G / 255F, color.B / 255F, color.A / 255F);
	public static implicit operator Vector4D<byte>(Color color) => new(color.R, color.G, color.B, color.A);
}