Loading & changing image inside control

D

dbui

Hi,

I got a simple ascx. It has one image component. When first loaded, it scans
thru \images folder, loads the first image, and save the index & the string
array of picture names in session.

When user click on the Next button, it will increase the index by one and
reload the image according to this new index value.

I want this web-control to be able to refresh itself every 5 seconds. And it
could increase the index and load the image of this index in the array
names.

What is the best way in asp.net (not other scripts) to archieve this?

Thanks.
 
K

Ken Cox [Microsoft MVP]

One way is to use some HTML in the page to cause the refresh and a Session
variable to track the index. I'm using a label for convenience here but
you'd want to pass Session("imageno") to your routine:


' This is the web user control
Private Sub Page_Load _
(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles MyBase.Load
If IsNothing(Session("imageno")) Then
Label1.Text = "Get the first image."
Else
Label1.Text = "Go get image # " & _
Session("imageno").ToString
End If
End Sub

' This is in the .aspx.vb code behind
Private Sub Page_Load _
(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles MyBase.Load
Session("imageno") = Session("imageno") + 1
End Sub

Private Sub Button1_Click _
(ByVal sender As System.Object, ByVal e As System.EventArgs) _
Handles Button1.Click
End Sub

This is the .aspx page

<%@ Register TagPrefix="uc1" TagName="imgfle" Src="imgfle.ascx" %>
<%@ Page Language="vb" AutoEventWireup="false"
Codebehind="countimage.aspx.vb" Inherits="p4320work.countimage"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head><meta http-equiv="refresh" content="600">
<title>countimage</title>
<meta name="GENERATOR" content="Microsoft Visual Studio .NET 7.1">
<meta name="CODE_LANGUAGE" content="Visual Basic .NET 7.1">
<meta name="vs_defaultClientScript" content="JavaScript">
<meta name="vs_targetSchema"
content="http://schemas.microsoft.com/intellisense/ie5">
</head>
<body MS_POSITIONING="FlowLayout">
<form id="Form1" method="post" runat="server">
<p>
<uc1:imgfle id="Imgfle1" runat="server"></uc1:imgfle></p>
<p>
<asp:button id="Button1" runat="server"
Text="Next"></asp:button></p>
</form>
</body>
</html>
 
D

dbui

Thanks for the help KC. I just learned that meta-tag refreshing is
re-loading the page, not re-posting the page.

dbui


here is my final code 4 whoever may need
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
If (IsNothing(Session("P"))) Then

Dim pics() As String =
Directory.GetFileSystemEntries(Server.MapPath("\images"), "*.jpg")

If pics.Length > 0 Then

Image1.ImageUrl = pics(0)

Session("P") = pics

Session("i") = 0

End If

Else

Dim pics() As String = Session("P")

Dim i As Integer = Session("i") + 1

If (i >= pics.Length) Then i = 0

Image1.ImageUrl = pics(i)

Session("i") = i

End If

End Sub
 

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