在图片上加水印或写字

使用一般处理程序在已有图片上加水印或者写字

public void ProcessRequest(HttpContext context)

        {

            context.Response.ContentType = "text/plain";

            //原图

            System.Drawing.Bitmap bitmap = new Bitmap(context.Server.MapPath("Uploads/201307269946.jpg"));

            //水印图

            System.Drawing.Bitmap bitmap1 = new Bitmap(context.Server.MapPath("Uploads/201307269390.png"));



            Graphics g = Graphics.FromImage(bitmap);



            //Drawing String

            //g.DrawString("www.cnblogs.com/g1mist", new Font("黑体", 30), Brushes.Red, new PointF(10, 60));



            //Drawing Images

            //将水印图画在原图的(10,60)位置上

            g.DrawImage(bitmap1, new Point(10, 60));



            bitmap.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);



        }

　　但是，一个一般处理程序一次在一张图片上加水印，如果需要在每一个对图片的请求中都对图片加上水印，那就要使用全局处理程序，新建一个类"WaterMarkHelper",并且实现IHttpHandler接口

public class WaterMarkHelper : IHttpHandler

    {

        public void ProcessRequest(HttpContext context)

        {

            //原始请求路径

            string rawurl = context.Request.RawUrl;

            //取到物理路径

            string path = context.Server.MapPath(rawurl);

            //取到水印的路径

            string logoPath = context.Server.MapPath("201307269390.png");



            //原图

            using (Image img = Image.FromFile(path))

            {

                //水印图

                using (Image logoImage = Image.FromFile(logoPath))

                {

                    //原图为画板

                    using (Graphics g = Graphics.FromImage(img))

                    {

                        //在原图上画上水印

                        g.DrawImage(logoImage, 10, 60, logoImage.Width, logoImage.Height);



                        //保存图片

                        img.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);

                    }

                }

            }

        }



        public bool IsReusable

        {

            get { return false; }

        }

    }

　　接着在Web.config中进行配置：

　　.net 4.5:

　　

<configuration>

  <system.web>

    <compilation debug="true" targetFramework="4.5" />

    <httpRuntime targetFramework="4.5" />

  </system.web>

  <system.webServer>

    <handlers>

      <add name="water" verb="*" path="Uploads/*.jpg" type="FileUpload.WaterMarkHelper"/>

    </handlers>

  </system.webServer>

</configuration>

　　.net 4.0

　　

<configuration>

  <system.web>

    <compilation debug="true" targetFramework="4.5" />

    <httpRuntime targetFramework="4.5" />

    <httpHandlers>

      <add verb="*" path="Uploads/*.jpg" type="FileUpload.WaterMarkHelper"/>

    </httpHandlers>

  </system.web>

</configuration>

　　type: "命名空间.类名,程序集名称",如果没有命名空间就只写类名。和网站在同一个程序集就不用写程序及名称