ASP.NET Image Generation内置了ImageResizeTransform类，可以实现图片大小调整功能。
也可以扩展ImageTransform实现自己的图片变换类。
下面使用ASP.NET Image Generation生成图片缩略图及水印的代码：
数据库
CREATE TABLE t_images
(
image_id INT,
image_data IMAGE,
last_modified_date, DATETIME
)
Default.aspx
Code
1@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="NET35Lab.GeneratedImage.Web._Default"
1@ Register Assembly="Microsoft.Web.GeneratedImage" Namespace="Microsoft.Web" TagPrefix="cc1"
1<html xmlns=" http://www.w3.org/1999/xhtml ">
2<head runat="server">
3<title></title>
4</head>
5<body>
6<form id="form1" runat="server">
7<div>
8<asp:datalist cellpadding="4" cellspacing="4" datasourceid="SqlDataSource1" id="DataList1" repeatcolumns="2" repeatdirection="Horizontal" runat="server">
9<itemtemplate>
10<cc1:generatedimage id="GeneratedImage1" imagehandlerurl="~/ImageHandler1.ashx" runat="server" timestamp='```
11# Eval("last_modified_date")
12```'>
13<parameters>
14<cc1:imageparameter name="imageid" value='```
15# Eval("image_id")
16```'></cc1:imageparameter>
17</parameters>
18</cc1:generatedimage>
19<br/>
20</itemtemplate>
21</asp:datalist>
22</div>
23<asp:sqldatasource connectionstring="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;User Instance=True;" id="SqlDataSource1" providername="System.Data.SqlClient" runat="server" selectcommand="SELECT [image_id], [image_data], [last_modified_date] FROM [t_images]">
24</asp:sqldatasource>
25</form>
26</body>
27</html>
ImageHandler1.ashx
1@ WebHandler Language="C#" CodeBehind="ImageHandler1.ashx.cs" Class="NET35Lab.GeneratedImage.Web.ImageHandler1"
ImageHandler1.ashx.cs
Code
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using Microsoft.Web;
using System.Collections.Specialized;
using System.Data.SqlClient;
using System.Drawing;
namespace NET35Lab.GeneratedImage.Web
{
public class ImageHandler1 : ImageHandler
{
public ImageHandler1()
{
this.ImageTransforms.Add(new ImageResizeTransform { Width = 320, Mode = ImageResizeMode.Fit });
this.ImageTransforms.Add(new CopyrightTransform { Text = "Guushuuse .NET" });
this.EnableClientCache = true;
this.EnableServerCache = true;
}
public override ImageInfo GenerateImage(NameValueCollection parameters)
{
int imageID = int.Parse(parameters["imageid"]);
SqlConnection connection = new SqlConnection(
@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;User Instance=True;");
connection.Open();
SqlCommand command = new SqlCommand("select image_data from t_images where image_id=" + imageID, connection);
SqlDataReader dr = command.ExecuteReader();
dr.Read();
return new ImageInfo((Byte[])dr[0]);
}
}
public class CopyrightTransform : ImageTransform
{
private const int VERTICAL_PADDING = 5;
private const int HORIZONAL_PADDING = 5;
public string Text { get; set; }
public Font Font { get; set; }
public Color FontColor { get; set; }
public CopyrightTransform()
{
//Assign Defaults
FontColor = Color.FromArgb(128, 255, 0, 0);
Font = new Font("Courier", 13);
}
public override System.Drawing.Image ProcessImage(System.Drawing.Image img)
{
Graphics gra = Graphics.FromImage(img);
SizeF sz = gra.MeasureString(Text, Font);
gra.DrawString(Text, Font, new SolidBrush(FontColor), img.Width - sz.Width - HORIZONAL_PADDING, img.Height - sz.Height - VERTICAL_PADDING);
return img;
}
public override string UniqueString
{
get
{
return base.UniqueString + Text + FontColor.ToString() + Font.ToString();
}
}
}
}