asp. net watermark specific implementation code

The watermark is to prevent us from stealing our images.

Two ways to achieve watermark effect

1) Watermark can be added when the user uploads.

a) Benefits: The server sends the image directly to the customer each time the user reads it, as opposed to the two methods.

Faults: corrupted original image.

2) Through the global 1 general processor, when the user requests the image, add watermark.

a) Benefit: The original image is not destroyed

b) Disadvantages: Every time the user requests, the requested image needs to be watermarked, which wastes the resources of the server.

Code to achieve the second way:

using System;   
using System.Collections.Generic;   
using System.Linq;   
using System.Web;   
using System.Drawing;   
using System.IO;   

namespace BookShop.Web   
{   
    public class WaterMark : IHttpHandler   
    {   

        private const string WATERMARK_URL = "~/Images/watermark.jpg";        // The watermark image    
        private const string DEFAULTIMAGE_URL = "~/Images/default.jpg";<span style="white-space:pre">   </span>      // The default image    
        #region IHttpHandler  Members of the    

        public bool IsReusable   
        {   
            get { return false; }   
        }   

        public void ProcessRequest(HttpContext context)   
        {   

            //context.Request.PhysicalPath  // Gets the physical path to the file requested by the user    

            System.Drawing.Image Cover;   
            // Determines whether a file exists in the physical path of the request    
            if (File.Exists(context.Request.PhysicalPath))   
            {   
                // Load the file    
                Cover = Image.FromFile(context.Request.PhysicalPath);   
                // Loaded watermark image    
                Image watermark = Image.FromFile(context.Request.MapPath(WATERMARK_URL));   
            // Get a drawing image from the book cover    
                Graphics g = Graphics.FromImage(Cover);   
                // in image Watermark on top    
                g.DrawImage(watermark, new Rectangle(Cover.Width - watermark.Width, Cover.Height - watermark.Height,    
[csharp] view plaincopy 
watermark.Width, watermark.Height), 0, 0, watermark.Width, watermark.Height, GraphicsUnit.Pixel);   
                // The release of the canvas    
                g.Dispose();   
                // Release watermark image    
                watermark.Dispose();   
            }   
            else  
            {   
                // Load the default image    
                Cover = Image.FromFile(context.Request.MapPath(DEFAULTIMAGE_URL));   
            }   
            // Set the output format    
            context.Response.ContentType = "image/jpeg";   
            // Store the image in the output stream    
            Cover.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);   
            Cover.Dispose();   
            context.Response.End();   
        }   

        #endregion   
    }   
}