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
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="NET35Lab.GeneratedImage.Web._Default" %>
<%@ Register Assembly="Microsoft.Web.GeneratedImage" Namespace="Microsoft.Web" TagPRefix="cc1" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:DataList ID="DataList1" runat="server" DataSourceID="SqlDataSource1" RepeatColumns="2"
RepeatDirection="Horizontal" CellPadding="4" CellSpacing="4">
<ItemTemplate>
<cc1:GeneratedImage ID="GeneratedImage1" runat="server" ImageHandlerUrl="~/ImageHandler1.ashx"
Timestamp=’<%# Eval("last_modified_date") %>’>
<Parameters>
<cc1:ImageParameter Name="imageid" Value=’<%# Eval("image_id") %>’ />
</Parameters>
</cc1:GeneratedImage>
<br />
</ItemTemplate>
</asp:DataList>
</div>
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="Data Source=.SQLEXPRESS;AttachDbFilename=|DataDirectory|Database.mdf;Integrated Security=True;User Instance=True;"
ProviderName="System.Data.SqlClient" SelectCommand="SELECT [image_id], [image_data], [last_modified_date] FROM [t_images]">
</asp:SqlDataSource>
</form>
</body>
</html>
ImageHandler1.ashx
<%@ 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();
}
}
}
}