给图片加文字的方法

if (!Page.IsPostBack)  
{  
    try  
    {  
        string str = Server.MapPath("~/upload/test.jpg");  
        System.Drawing.Image myImage = System.Drawing.Image.FromFile(str);  
        Bitmap map = new Bitmap(myImage);  
        myImage.Dispose();  
        Graphics graphics = Graphics.FromImage(map);  
        graphics.InterpolationMode = InterpolationMode.HighQualityBilinear;  
        SolidBrush brush = new SolidBrush(Color.Red);  
        PointF P = new PointF(100, 100);  
        Font font = new Font("宋体", 40);  
        graphics.DrawString("guwei4037", font, brush, P);  
        map.Save(str.Substring(0, str.LastIndexOf("\\") + 1) + "new" + str.Substring(str.LastIndexOf("\\") + 1, str.LastIndexOf(".") - str.LastIndexOf("\\") - 1) + str.Substring(str.LastIndexOf("."), str.Length - str.LastIndexOf(".")), ImageFormat.Jpeg);  
        font.Dispose();  
        graphics.Dispose();  
    }  
    catch { }  
}