ARCed.Scintilla.XpmConverter.ConvertToXPM C# (CSharp) Method

        public static string ConvertToXPM(Bitmap bmp, string transparentColor)
        {
            var sb = new StringBuilder();
            var colors = new List<string>();
            var chars = new List<char>();
            int width = bmp.Width;
            int height = bmp.Height;
            int index;
            sb.Append("/* XPM */static char * xmp_data[] = {\"").Append(width).Append(" ").Append(height).Append(" ? 1\"");
            int colorsIndex = sb.Length;
            string col;
            char c;
            for (int y = 0; y < height; y++)
            {
                sb.Append(",\"");
                for (int x = 0; x < width; x++)
                {
                    col = ColorTranslator.ToHtml(bmp.GetPixel(x, y));
                    index = colors.IndexOf(col);
                    if (index < 0)
                    {
                        index = colors.Count + 65;
                        colors.Add(col);
                        if (index > 90) index += 6;
                        c = Encoding.ASCII.GetChars(new[] { (byte)(index & 0xff) })[0];
                        chars.Add(c);
                        sb.Insert(colorsIndex, ",\"" + c + " c " + col + "\"");
                        colorsIndex += 14;
                    }
                    else c = chars[index];
                    sb.Append(c);
                }
                sb.Append("\"");
            }
            sb.Append("};");
            string result = sb.ToString();
            int p = result.IndexOf("?");
            string finalColor = result.Substring(0, p) + colors.Count + result.Substring(p + 1).Replace(transparentColor.ToUpper(), "None");

            return finalColor;
        }