asp.net、C#动态添加图片水印

例子1：

web.config

<httpHandlers>
<remove verb="*" path="*.asmx"/>
<add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
<add verb="*" path="*_AppService.axd" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
<add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" validate="false"/>
<add verb="*" path="images/shangjia/*/*.jpg" type="CoverHandler"/>
<add verb="*" path="images/shangjia/*/*/*.jpg" type="CoverHandler"/>
<add verb="*" path="admin/TotalUpImg/VedioImg/*.jpg" type="CoverHandler1"/>
</httpHandlers>
<httpHandlers>

<remove verb="*" path="*.asmx"/>
<add verb="*" path="*.asmx" validate="false"
type="System.Web.Script.Services.ScriptHandlerFactory,
System.Web.Extensions, Version=1.0.61025.0, Culture=neutral,
PublicKeyToken=31bf3856ad364e35"/>
<add verb="*" path="*_AppService.axd" validate="false"
type="System.Web.Script.Services.ScriptHandlerFactory,
System.Web.Extensions, Version=1.0.61025.0, Culture=neutral,
PublicKeyToken=31bf3856ad364e35"/>
<add verb="GET,HEAD" path="ScriptResource.axd"
type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions,
Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
validate="false"/>
<add verb="*" path="images/shangjia/*/*.jpg"
type="CoverHandler"/>
<add verb="*" path="images/shangjia/*/*/*.jpg"
type="CoverHandler"/>
<add verb="*" path="admin/TotalUpImg/VedioImg/*.jpg"
type="CoverHandler1"/>
</httpHandlers>

CoverHandler.cs

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;

/// <summary>
/// CoverHandler 的摘要说明
/// </summary>
public class CoverHandler : IHttpHandler
{
public CoverHandler()
{
//
// TODO: 在此处添加构造函数逻辑
//
}
private const string WATERMARK_URL = "~/images/WaterMark.png";
private const string DEFAULTIMAGE_URL = "~/images/default.jpg";
#region IHttpHandler 成员

public void ProcessRequest(HttpContext context)
{
System.Drawing.Image Cover;
if (File.Exists(context.Request.PhysicalPath))
{
Cover = Image.FromFile(context.Request.PhysicalPath);
Image watermark = Image.FromFile(context.Request.MapPath(WATERMARK_URL));
Graphics g = Graphics.FromImage(Cover);
Random r = new Random();
int width = r.Next(10,Cover.Width - watermark.Width);
int height = r.Next(10,Cover.Height - watermark.Height);
g.DrawImage(watermark, new Rectangle(width, height, watermark.Width, watermark.Height), 0, 0, watermark.Width, watermark.Height, GraphicsUnit.Pixel);
g.Dispose();
watermark.Dispose();
}
else
{
Cover = Image.FromFile(context.Request.MapPath(DEFAULTIMAGE_URL));
}
context.Response.ContentType = "image/Jpeg";
Cover.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
Cover.Dispose();
context.Response.End();

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

#endregion
}

例子2:

WaterMarke.cs 类 code

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
/// <summary>
/// WaterMarker 的摘要说明
/// </summary>
public class WaterMarker : IHttpHandler
{
public WaterMarker()
{
//
// TODO: 在此处添加构造函数逻辑
//
}
public bool IsReusable
{
get { return true; }
}
public void ProcessRequest(HttpContext context)
{
//获取请求的物理路径
string imagePath = context.Request.PhysicalPath;
System.Drawing.Image image = null;
//判断指定的物理路径是否存在
if (File.Exists(imagePath))
{
//定义水印文字
string text = "本图片来自夏楚枫的博客";
//定义水印文字字体的大小
int fontSize = 12;
//水印文字字体
Font font = new Font("宋体", fontSize);
//根据图片的物理路径加载图片
image = System.Drawing.Image.FromFile(imagePath);
Graphics g = Graphics.FromImage(image);
//获取要绘制水印文字所需要区域的大小
SizeF size = g.MeasureString(text, font);
if (size.Width > image.Width || size.Height > image.Height)
{
//如果要显示图片的尺寸都不足以显示按照指定文字字体来添加水印
//可以减小的字体的大小或者不添加水印（太小了没办法添加嘛）
}
else
{
//添加水印文字
Brush br = Brushes.Red;
g.DrawString(text, font, br, image.Width - size.Width, image.Height - size.Height);
g.Dispose();
}

}
else //如果不存在指定一个默认的图片进行显示http://www.xuehai.net
{
imagePath = context.Server.MapPath("~/image/default.jpg");
image = System.Drawing.Image.FromFile(imagePath);
}
image.Save(context.Response.OutputStream, ImageFormat.Jpeg);//将添加水印的图片输出

}
}

webconfig 中的配置

方法一：在所在文件夹添加一个webconfig文件，然后再在
<system.web>节点中添加下面的代码

<httpHandlers>
<!--对jpg文件添加水印-->
<add path="*" verb="*.jpg" type="WaterMarker"/>
<!--对bmp文件添加水印-->
<add verb="*" path="*.bmp" type="WaterMarker"/>
</httpHandlers>

方法二： 不在图片所在的文件夹下添加webconfig 而是直接在根目录下的webconfig中的配置

不用自动生成的那个<System.web>中配置 而是在<configuration>节点中添加如下代码

<location path="image">
<system.web>
<httpHandlers>
<!--对jpg文件添加水印-->
<add path="*" verb="*.jpg" type="WaterMarker"/>
<!--对bmp文件添加水印-->
<add verb="*" path="*.bmp" type="WaterMarker"/>
</httpHandlers>
</system.web>
</location>