在圖片上加水印或寫字

使用通常處理程序在已有圖片上加水印或者寫字

public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "text/plain";
            //原圖
            System.Drawing.Bitmap bitmap = new Bitmap(context.Server.MapPath("Uploads/201307269946.jpg"));
            //水印圖
            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("黑體", 30), Brushes.Red, new PointF(10, 60));

            //Drawing Images
            //將水印圖畫在原圖的(10,60)位置上
            g.DrawImage(bitmap1, new Point(10, 60));

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

        }

　　可是，一個通常處理程序一次在一張圖片上加水印，若是須要在每個對圖片的請求中都對圖片加上水印，那就要使用全局處理程序，新建一個類"WaterMarkHelper",而且實現IHttpHandler接口

public class WaterMarkHelper : IHttpHandler
    {
        public void ProcessRequest(HttpContext context)
        {
            //原始請求路徑
            string rawurl = context.Request.RawUrl;
            //取到物理路徑
            string path = context.Server.MapPath(rawurl);
            //取到水印的路徑
            string logoPath = context.Server.MapPath("201307269390.png");

            //原圖
            using (Image img = Image.FromFile(path))
            {
                //水印圖
                using (Image logoImage = Image.FromFile(logoPath))
                {
                    //原圖爲畫板
                    using (Graphics g = Graphics.FromImage(img))
                    {
                        //在原圖上畫上水印
                        g.DrawImage(logoImage, 10, 60, logoImage.Width, logoImage.Height);

                        //保存圖片
                        img.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
                    }
                }
            }
        }

        public bool IsReusable
        {
            get { return false; }
        }
    }

　　接着在Web.config中進行配置：

　　.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: "命名空間.類名,程序集名稱",若是沒有命名空間就只寫類名。和網站在同一個程序集就不用寫程序及名稱