Question

I’m trying to generate a grid of 1×1 pixels Images in .NET using VB.NET, using this code:

    For i = 1 To 500
        Dim img As New ImageButton
        img.ID = "ibtn" + i.ToString
        img.ImageUrl = "images/design/click.gif"
        form1.FindControl("upperpanel").Controls.Add(img)
    Next

Problem is that it takes a very long time to generate the HTML when I’m running this on page_load event. Can anyone help me out to speed up the rendering of the controls.
Also, I want to add Click event on each image button. How can I do that ??

Thanks

Answer 1

Ok, first thing to do is get the panel control once. Second, create your click method, and then add your handler. This needs to be done prior to the page load event. Use the page_Init event for creating your buttons when you need to add a handler.

    Private Sub WebForm1_Init(sender As Object, e As EventArgs) Handles Me.Init
    Dim tempPanel As Panel = form1.FindControl("upperpanel")

    If tempPanel Is Nothing Then
        Return
    End If

    For i = 1 To 500
        Dim img As New ImageButton
        img.ID = "ibtn" + i.ToString
        img.ImageUrl = "images/design/click.gif"
        AddHandler img.Click, AddressOf ImageButton_Click
        tempPanel.Controls.Add(img)
    Next
End Sub

Protected Sub ImageButton_Click(sender As Object, e As ImageClickEventArgs)
    Dim tempImageButton As ImageButton = CType(sender, ImageButton)

    Select Case tempImageButton.ID
        Case "ibtn1"
                    'blah
        Case Else
    End Select

End Sub

As far as performance goes, getting the panel control up front will improve performance. Probably not much. Creating 500 buttons is going to take some time.