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This article is about how to implement watermark in asp.net. Xiaobian thinks it is quite practical, so share it with everyone for reference. Let's follow Xiaobian and have a look.

Two ways to achieve watermark effect

1)Watermarks can be added when users upload.

a) Benefits: Compared to the two methods, each time the user reads this image, the server sends it directly to the client.

b) Disadvantages: Destroy the original image.

2)Through global general processing, when the user requests this image, watermark it.

a) Benefits: The original image is not corrupted

b) Disadvantages: users need to watermark the requested image every time they request, wasting server resources.

The code is implemented in the second way:

The code is as follows:

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"; //watermark image

private const string DEFAULTIMAGE_URL = "<$/Images/default. jpg"; //default image

#region IHttpHandler member

public bool IsReusable

{

get { return false; }

}

public void ProcessRequest(HttpContext context)

{

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

System.Drawing.Image Cover;

//Determine whether there is a file in the physical path of the request

if (File.Exists(context.Request.PhysicalPath))

{

//load file

Cover = Image.FromFile(context.Request.PhysicalPath);

//load watermark image

Image watermark = Image.FromFile(context.Request.MapPath(WATERMARK_URL));

//Get drawing object through book cover

Graphics g = Graphics.FromImage(Cover);

//Draw watermark on image

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);

//Release canvas

g.Dispose();

//release watermark image

watermark.Dispose();

}

else

{

//load default image

Cover = Image.FromFile(context.Request.MapPath(DEFAULTIMAGE_URL));

}

//Set output format

context.Response.ContentType = "image/jpeg";

//save images to output stream

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

Cover.Dispose();

context.Response.End();

}

#endregion

}

}

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