html页面颜色名称和颜色值转换

  public static string ToHtmlColor(string colorName)        {
            try
            {
                if (colorName.StartsWith("#"))
                    colorName = colorName.Replace("#", string.Empty);
                int v = int.Parse(colorName, System.Globalization.NumberStyles.HexNumber);

                Color col = Color.FromArgb
               (
                     Convert.ToByte((v >> 24) & 255),
                     Convert.ToByte((v >> 16) & 255),
                     Convert.ToByte((v >> 8) & 255),
                     Convert.ToByte((v >> 0) & 255)
                );

                int alpha = col.A;
                var red = Convert.ToString(col.R, 16); ;
                var green = Convert.ToString(col.G, 16);
                var blue = Convert.ToString(col.B, 16);
                return string.Format("#{0}{1}{2}", red, green, blue);
            }
            catch
            {
                return "black";
            }
        }
       public static String ColorToStr(System.Drawing.Color color)
        {
            try
            {
                string color_s = System.Drawing.ColorTranslator.ToHtml(color);
                color_s = color_s.Substring(1, color_s.Length - 1);
                return "#" + Convert.ToString(Convert.ToInt32(color_s, 16) + 40000, 16);
            }
            catch
            {
                return "black";
            }
        }