for Push.

Forms/ColorHelper.cs

@@ -0,0 +1,74 @@
+using DocumentFormat.OpenXml.Wordprocessing;
+using KssSmaPlaLib.Ini;
+using System;
+using System.Collections.Generic;
+using System.Drawing;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Forms;
+using Color = System.Drawing.Color;
+
+namespace KssSmaPlaLib.Forms
+{
+    public static class ColorHelper
+    {
+        /// <summary>
+        /// 色選択
+        /// </summary>
+        /// <param name="form"></param>
+        /// <param name="defaultColor"></param>
+        /// <param name="iniKey"></param>
+        /// <returns></returns>
+        public static Color? SelectColor(Form form, Color defaultColor, string iniKey = "")
+        {
+            using (ColorDialog cd = new ColorDialog())
+            {
+                // 今の色を初期選択にしておく
+                cd.Color = defaultColor;
+
+                if (cd.ShowDialog(form) != DialogResult.OK) return null;
+
+                if (!string.IsNullOrEmpty(iniKey))
+                {
+                    // 2. 🔥 Colorを16進数（#RRGGBB）に変換してINIに書き込み
+                    string colorHex = ColorTranslator.ToHtml(cd.Color);
+                    IniHelper.WriteValue(null, form.Name, iniKey, colorHex);
+                }
+                return cd.Color;
+            }
+        }
+
+        /// <summary>
+        /// Colorを汎用的なHTML色コード文字列に変換する
+        /// </summary>
+        /// <param name="color"></param>
+        /// <returns></returns>
+        public static string ColorToHtmlColorString(Color color)
+        {
+            return ColorTranslator.ToHtml(color);
+        }
+
+        /// <summary>
+        /// 汎用的なHTML色コード文字列からColorに変換する
+        /// </summary>
+        /// <param name="htmlColorString"></param>
+        /// <returns></returns>
+        public static Color HtmlColorStringToColor(string htmlColorString)
+        {
+            return ColorTranslator.FromHtml(htmlColorString);
+        }
+
+        /// <summary>
+        /// 背景色から最適な文字色(黒/白)を返すメソッド
+        /// </summary>
+        /// <param name="backColor"></param>
+        /// <returns></returns>
+        public static Color GetContrastColor(Color backColor)
+        {
+            // 輝度計算 (ITU-R BT.601)
+            double luminance = (0.299 * backColor.R) + (0.587 * backColor.G) + (0.114 * backColor.B);
+            return (luminance > 128) ? Color.Black : Color.White;
+        }
+    }
+}