asp.net縮略圖和水印制作:Image Generation

　　aspnet Image Generation內置了ImageResizeTransform類可以實現圖片大小調整功能
也可以擴展ImageTransform實現自己的圖片變換類
下面使用ASPNET Image Generation生成圖片縮略圖及水印的代碼

數據庫
CREATE TABLE t_images
(
image_id INT
image_data IMAGE
last_modified_date DATETIME
)

Defaultaspx

Code
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Defaultaspxcs" Inherits="NETLabGeneratedImageWeb_Default" %>

<%@ Register Assembly="MicrosoftWebGeneratedImage" Namespace="MicrosoftWeb" TagPRefix="cc" %>
<!DOCTYPE html PUBLIC "//WC//DTD XHTML  Transitional//EN" "
<html xmlns="
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form" runat="server">
    <div>
        <asp:DataList ID="DataList" runat="server" DataSourceID="SqlDataSource" RepeatColumns=""
            RepeatDirection="Horizontal" CellPadding="" CellSpacing="">
            <ItemTemplate>
                <cc:GeneratedImage ID="GeneratedImage" runat="server" ImageHandlerUrl="~/ImageHandlerashx"
                    Timestamp=’<%# Eval("last_modified_date") %>’>
                    <Parameters>
                        <cc:ImageParameter Name="imageid" Value=’<%# Eval("image_id") %>’ />
                    </Parameters>
                </cc:GeneratedImage>
                <br />
            </ItemTemplate>
        </asp:DataList>
    </div>
    <asp:SqlDataSource ID="SqlDataSource" runat="server" ConnectionString="Data Source=SQLEXPRESS;AttachDbFilename=|DataDirectory|Databasemdf;Integrated Security=True;User Instance=True;"
        ProviderName="SystemDataSqlClient" SelectCommand="SELECT [image_id] [image_data] [last_modified_date] FROM [t_images]">
    </asp:SqlDataSource>
    </form>
</body>
</html>

ImageHandlerashx

<%@ WebHandler Language="C#" CodeBehind="ImageHandlerashxcs" Class="NETLabGeneratedImageWebImageHandler" %>

ImageHandlerashxcs

Code
using System;
using SystemCollectionsGeneric;
using SystemLinq;
using SystemWeb;
using MicrosoftWeb;
using SystemCollectionsSpecialized;
using SystemDataSqlClient;
using SystemDrawing;

namespace NETLabGeneratedImageWeb
{

    public class ImageHandler : ImageHandler
    {

        public ImageHandler()
        {
            thisImageTransformsAdd(new ImageResizeTransform { Width =  Mode = ImageResizeModeFit });
            thisImageTransformsAdd(new CopyrightTransform { Text = "Guushuuse NET" });
            thisEnableClientCache = true;
            thisEnableServerCache = true;

        }

        public override ImageInfo GenerateImage(NameValueCollection parameters)
        {

            int imageID = intParse(parameters["imageid"]);

            SqlConnection connection = new SqlConnection(
                @"Data Source=SQLEXPRESS;AttachDbFilename=|DataDirectory|Databasemdf;Integrated Security=True;User Instance=True;");

            connectionOpen();

            SqlCommand command = new SqlCommand("select image_data from t_images where image_id=" + imageID connection);

            SqlDataReader dr = commandExecuteReader();

            drRead();

            return new ImageInfo((Byte[])dr[]);

        }
    }

    public class CopyrightTransform : ImageTransform
    {
        private const int VERTICAL_PADDING = ;
        private const int HORIZONAL_PADDING = ;

        public string Text { get; set; }
        public Font Font { get; set; }
        public Color FontColor { get; set; }

        public CopyrightTransform()
        {
            //Assign Defaults
            FontColor = ColorFromArgb(   );
            Font = new Font("Courier" );
        }

        public override SystemDrawingImage ProcessImage(SystemDrawingImage img)
        {
            Graphics gra = GraphicsFromImage(img);
            SizeF sz = graMeasureString(Text Font);
            graDrawString(Text Font new SolidBrush(FontColor) imgWidth  szWidth  HORIZONAL_PADDING imgHeight  szHeight  VERTICAL_PADDING);
            return img;
        }

        public override string UniqueString
        {
            get
            {
                return baseUniqueString + Text + FontColorToString() + FontToString();
            }
        }
    }
}

From:http://tw.wingwit.com/Article/program/net/201311/14282.html