ASP.NET(c#) 图片水印

if (FileUpload1.PostedFile.ContentType.ToLower().IndexOf("image") < 0)
{
FunctionUtility.JavaScriptHelper.Alert("上传的文件格式不正确！");
return;
}

 Stream oStream = FileUpload1.PostedFile.InputStream;
 System.Drawing.Image oImage = System.Drawing.Image.FromStream(oStream);

 if(CheckBox1.Checked)
{
//加文字水印
Graphics g = Graphics.FromImage(oImage);
g.DrawImage(oImage, 0, 0, oImage.Width, oImage.Height);
Font f = new Font("Verdana",15);
Brush b = new SolidBrush(Color.White);
g.DrawString("http://www.itwealth.cn制作", f, b, 0, oImage.Height - 30);
g.Dispose();
}
else
{
//加图片水印
System.Drawing.Image copyImage = System.Drawing.Image.FromFile(Server.MapPath("/DesignImages/Images/SYT/Admin.jpg"));
Graphics g = Graphics.FromImage(oImage);
g.DrawImage(copyImage, new Rectangle(oImage.Width - copyImage.Width, oImage.Height - copyImage.Height, copyImage.Width, copyImage.Height), 0, 0, copyImage.Width, copyImage.Height, GraphicsUnit.Pixel);
g.Dispose();
}

string setFileName = FunctionUtility.FileHelper.GetDateTimeFileName() + ".jpg";
string oFullName = Server.MapPath("/DesignImages/Images/SYT/" + setFileName);
oImage.Save(oFullName, System.Drawing.Imaging.ImageFormat.Jpeg);
oImage.Dispose();

Image1.Visible = true;
Image1.ImageUrl = "/DesignImages/Images/SYT/" + setFileName;
FunctionUtility.JavaScriptHelper.Alert("水印加载成功！");