csharp: 图片字符间距

        [DllImport("gdi32.dll", CharSet = CharSet.Auto)]
        public static extern int SetTextCharacterExtra(IntPtr hdc, int nCharExtra);//图片字符间距
        [DllImport("gdi32.dll")]
        public static extern bool DeleteObject(IntPtr handle);
        [DllImport("gdi32.dll")]
        public static extern IntPtr SelectObject(IntPtr hdc, IntPtr bmp);

/// <summary>
        /// 
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        /// <param name="fontSpace"></param>
        private void pictureBox_Paint(object sender, PaintEventArgs e)
        {
            Graphics g = e.Graphics;
            Font font = new Font("宋体", 12.0F);

            Brush brush = Brushes.Red;
            string text2 = "涂聚文";
            IntPtr hdc = e.Graphics.GetHdc();
            SetTextCharacterExtra(hdc, 16); // 设置字符间距   
            e.Graphics.ReleaseHdc(hdc);
            e.Graphics.DrawString(text2, font, brush, 20, 25);//

            //pictureBox1.Paint += new System.Windows.Forms.PaintEventHandler(this.pictureBox1_Paint);
        }

 /// <summary>
        /// 图片的字符间距(只对中文，数字，字母，符号有效，在中文环境下，中文日文混排无效)
        /// 涂聚文
        /// .net3.0以上
        /// </summary>
        /// <param name="width">图片宽度</param>
        /// <param name="height">图片高度</param>
        /// <param name="space">字间距</param>
        /// <param name="strtext">要显示的文字</param>
        /// <returns>图片</returns>
        Bitmap CreateImageString(int width, int height,int space ,string strtext)
        {
            Bitmap image = new Bitmap(width, height);
            using (Graphics g = Graphics.FromImage(image))
            {
                //绘制图片边框
                //g.DrawRectangle(Pens.Black, 0, 0, width - 1, height - 1);

                Font font = new Font("宋体", 12.0F);

                Brush brush = Brushes.Red;
                //绘制设置了字符间距的输出
                DrawStringExtra(g, space, x =>
                {
                    x.DrawString(strtext, font, brush, 0, 2);
                });
            }
            return image;
        }


        /// <summary>
        /// 
        /// </summary>
        /// <param name="g"></param>
        /// <param name="nCharExtra"></param>
        /// <param name="action"></param>
        void DrawStringExtra(Graphics g, int nCharExtra, Action<Graphics> action)
        {
            IntPtr hdc = g.GetHdc();
            SetTextCharacterExtra(hdc, nCharExtra);
            try
            {
                using (Graphics g1 = Graphics.FromHdc(hdc))
                {
                    action(g1);
                }
            }
            finally
            {
                SetTextCharacterExtra(hdc, 0);
                g.ReleaseHdc(hdc);
            }
        }

 pictureBox1.Image = CreateImageStrin(100, 30, 10, "3315000");