Add ColorExtensions for System.Drawing.Color

PowerKit.Tests/Extensions/ColorExtensionsTests.cs

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+using System.Drawing;
+using FluentAssertions;
+using PowerKit.Extensions;
+using Xunit;
+
+namespace PowerKit.Tests.Extensions;
+
+public class ColorExtensionsTests
+{
+    [Fact]
+    public void ToHex_Test()
+    {
+        // Act & assert
+        Color.FromArgb(255, 0x12, 0x34, 0x56).ToHex().Should().Be("#123456");
+        Color.FromArgb(128, 0xff, 0x00, 0x00).ToHex().Should().Be("#FF0000");
+        Color.FromArgb(255, 0x00, 0x00, 0x00).ToHex().Should().Be("#000000");
+        Color.FromArgb(255, 0xff, 0xff, 0xff).ToHex().Should().Be("#FFFFFF");
+    }
+
+    [Fact]
+    public void ToRgb_Test()
+    {
+        // Act & assert
+        Color.FromArgb(255, 0x12, 0x34, 0x56).ToRgb().Should().Be(0x123456);
+        Color.FromArgb(0, 0x12, 0x34, 0x56).ToRgb().Should().Be(0x123456);
+        Color.FromArgb(255, 0x00, 0x00, 0x00).ToRgb().Should().Be(0x000000);
+        Color.FromArgb(255, 0xff, 0xff, 0xff).ToRgb().Should().Be(0xffffff);
+    }
+
+    [Fact]
+    public void WithAlpha_Test()
+    {
+        // Act & assert
+        Color.FromArgb(255, 0x12, 0x34, 0x56).WithAlpha(128).A.Should().Be(128);
+        Color.FromArgb(255, 0x12, 0x34, 0x56).WithAlpha(128).R.Should().Be(0x12);
+        Color.FromArgb(255, 0x12, 0x34, 0x56).WithAlpha(128).G.Should().Be(0x34);
+        Color.FromArgb(255, 0x12, 0x34, 0x56).WithAlpha(128).B.Should().Be(0x56);
+        Color.FromArgb(0, 0xff, 0xff, 0xff).WithAlpha(255).A.Should().Be(255);
+    }
+
+    [Fact]
+    public void ResetAlpha_Test()
+    {
+        // Act & assert
+        Color.FromArgb(0, 0x12, 0x34, 0x56).ResetAlpha().A.Should().Be(255);
+        Color.FromArgb(128, 0x12, 0x34, 0x56).ResetAlpha().A.Should().Be(255);
+        Color.FromArgb(255, 0x12, 0x34, 0x56).ResetAlpha().A.Should().Be(255);
+        Color.FromArgb(0, 0x12, 0x34, 0x56).ResetAlpha().R.Should().Be(0x12);
+        Color.FromArgb(0, 0x12, 0x34, 0x56).ResetAlpha().G.Should().Be(0x34);
+        Color.FromArgb(0, 0x12, 0x34, 0x56).ResetAlpha().B.Should().Be(0x56);
+    }
+}

PowerKit/Extensions/ColorExtensions.cs

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+#nullable enable
+using System.Diagnostics.CodeAnalysis;
+using System.Drawing;
+
+namespace PowerKit.Extensions;
+
+#if !POWERKIT_INCLUDE_COVERAGE
+[ExcludeFromCodeCoverage]
+#endif
+internal static class ColorExtensions
+{
+    extension(Color color)
+    {
+        /// <summary>
+        /// Returns the hexadecimal representation of the color (e.g., <c>#RRGGBB</c>).
+        /// </summary>
+        public string ToHex() => $"#{color.R:X2}{color.G:X2}{color.B:X2}";
+
+        /// <summary>
+        /// Returns the RGB value of the color as a 32-bit integer (without the alpha channel).
+        /// </summary>
+        public int ToRgb() => color.ToArgb() & 0xffffff;
+
+        /// <summary>
+        /// Returns a new <see cref="Color" /> with the specified alpha value.
+        /// </summary>
+        public Color WithAlpha(int alpha) => Color.FromArgb(alpha, color);
+
+        /// <summary>
+        /// Returns a new <see cref="Color" /> with the alpha channel reset to fully opaque.
+        /// </summary>
+        public Color ResetAlpha() => color.WithAlpha(255);
+    }
+}