/// <summary>

        /// 截取指定像素长度的字符串

        /// </summary>

        /// <param name="str">需要截取的字符串</param>

        /// <param name="length">像素长度</param>

        /// <returns></returns>

        public static string GetStringByPixel(string str, int length)

        {

            Bitmap bmp = new Bitmap(1, 1);

            Graphics graphics = Graphics.FromImage(bmp);

            float width = 0;

            SizeF sizeF;

            Font f = new Font("宋体", 13);

            StringBuilder sb = new StringBuilder();

            foreach (char c in str)

            {

                sizeF = graphics.MeasureString(c.ToString(), f);

                width += sizeF.Width;

                if (width > length)

                    return sb.ToString();

                else

                    sb.Append(c);

            }

            graphics.Dispose();

            bmp.Dispose();

            return sb.ToString();

        }