- DataGrid shows that the use of images from the database | Programing Reference For .Net,Java,C

DataGrid shows that the use of images from the database

Foreword

How do we create a DataGrid out that obtained from the database image?

This is a frequently asked question on the DataGrid control, and other can easily be through a combination of you already know about the content of the template are a little handle on the handling HTTP (HTTP Handler) knowledge to answer.

Below NorthWind use of the database to the Employees table in a DataGrid to display images in the database.

Code

— BindImg.aspx

<% @ Page language = "c #" Codebehind = "BindImg.aspx.cs" AutoEventWireup = "false" Inherits = "ShowImg.BindImg"%>
<HTML>
<HEAD>
<title> BindImg </ title>
</ HEAD>
<body>
<form Id="Form1" method="post" runat="server">
<FONT Face="å®‹ä½“">
<asp:DataGrid Id="MyDataGrid" runat="server" AutoGenerateColumns="False" Width="632px">
<AlternatingItemStyle BackColor="Beige"> </ AlternatingItemStyle>
<HeaderStyle HorizontalAlign="Center"> </ HeaderStyle>
<Columns>
<asp:TemplateColumn HeaderText="Photo">
<ItemTemplate>
<Img src ='<%# "GetImg.ashx? ID =" + DataBinder.Eval (Container.DataItem, "EmployeeID ")%>'>
</ ItemTemplate>
</ Asp: TemplateColumn>
<asp:BoundColumn DataField="LastName" HeaderText="Last Name"> </ asp: BoundColumn>
<asp:BoundColumn DataField="FirstName" HeaderText="First Name"> </ asp: BoundColumn>
<asp:BoundColumn DataField="title" HeaderText="Title"> </ asp: BoundColumn>
</ Columns>
</ Asp: DataGrid> </ FONT>
</ Form>
</ Body>
</ HTML>

— BindImg.aspx.cs

Using System;
Using System.Data;
Using System.Drawing;
Using System.Web;

Using System.Data.SqlClient;

Namespace ShowImg
(
/ / / <summary>
/ / / BindImg explanatory memorandum.
/ / / </ Summary>
Public class BindImg: System.Web.UI.Page
(
Protected System.Web.UI.WebControls.DataGrid MyDataGrid;

Private void Page_Load (object sender, System.EventArgs e)
(
/ / User code placed here to initialize pages
If (! Page.IsPostBack)
(
SqlConnection conn = new SqlConnection (@ "Server = shoutor \ mydb; database = northwind; uid = sa; Pwd = shoutor");
Try
(
Conn.Open ();
SqlCommand cmd = new SqlCommand ( "select employeeID, lastname, firstname, title from employees," conn);
SqlDataReader reader = cmd.ExecuteReader ();
MyDataGrid.DataSource = reader;
MyDataGrid.DataBind ();
)
Finally
(
Conn.Close ();
)
)
)
# Region Web form designer generated code
Override protected void OnInit (EventArgs e)
(
/ /
/ / CODEGEN: The call is ASP.NET Web Forms designer necessary.
/ /
InitializeComponent ();
Base.OnInit (e);
)

/ / / <summary>
/ / / Designer support of the approach - Do not use the code editor Laws
/ / / The contents of this method.
/ / / </ Summary>
Private void InitializeComponent ()
(
This.Load + = new System.EventHandler (this.Page_Load);
)
# Endregion
)
)

— GetImg.ashx

<% @ WebHandler Language = "C #" Class = "ShowImg.GetImg"%>

— GetImg.aspx.cs

Using System;
Using System.Web;
Using System.Data;
Using System.Data.SqlClient;
Using System.Drawing;
Using System.Drawing.Imaging;
Using System.IO;

Namespace ShowImg
(
/ / / <summary>
/ / / GetImg explanatory memorandum.
/ / / </ Summary>
Public class GetImg: IHttpHandler
(
Public void ProcessRequest (HttpContext context)
(
String id = (string) context.Request [ "id"];
If (id! = Null)
(
MemoryStream stream = new MemoryStream ();
SqlConnection conn = new SqlConnection (@ "Server = shoutor \ mydb; database = northwind; uid = sa; Pwd = shoutor");
Bitmap bm = null;
Image image = null;
Try
(
Conn.Open ();
SqlCommand cmd = new SqlCommand ( "select photo from employees where employeeid = '" + id +"'", conn);
Byte [] blob = (byte []) cmd.ExecuteScalar ();
Stream.Write (blob, 78, blob.Length-78);
Bm = new Bitmap (stream);

Int width = 48;
Int height = (int) (width * ((double) bm.Height / (double) bm.Width));
/ / GetThumbnailImage generate thumbnails
Image = bm.GetThumbnailImage (width, height, null, IntPtr.Zero);

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

Image.Save (context.Response.OutputStream, ImageFormat.Jpeg);
)
Finally
(
If (image! = Null)
Image.Dispose ();
If (bm! = Null)
Bm.Dispose ();
Stream.Close ();
Conn.Close ();
)
)
)

/ / Implementation of interface (System.Web.IHttpHandler.IsReusable)
Public bool IsReusable
(
Get
(
Return true;
)
)
)
)

Aggregate

As an extra added that the ProcessRequest also used the air-class library of easy-to-use approach to the Image.GetThumbnailImage bitmap reduced to the width of 48 pixels, while maintaining the image of the aspect ratio. Similar technology can be used to create a database of images from other shows that the DataGrid. The basic idea is to use a template are used to output a handle processing of HTTP <img> labels, and query strings unique identifier included in the picture of the recorded information. After processing HTTP handle use ADO.NET to access image data bits, and the use of GDI + (Image Device Interface +) to build images.

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