In the beginning

So you want to know how to generate an image with an ASP page on the fly? Well there is a few ways to do it, such as flash etc, but with Microsoft and GDI+ the task is made a lot easier. This tutorial just covers the basics, but from it you can always move on and experiment with GDI+ (and intellisense) :)

Well, lets start with the calling page default.aspx (or whatever you would like to call it):

I usually like to draw all my controls to a table using code, there are other ways to do it, but I like doing it this way:

  1. Add a TextBox to the default.aspx page calling it whatever you like (for the tutorial we'll call it txtWord)
  2. Add a CommandButton to the page and call it whatever you like (just to submit the form)
  3. Add a server side Table control (call it what you want I'll just call it imageTable)
  4. In the codebehind page (.aspx.vb) add the following code, or similar to the Page_Load procedure

         Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
           ' #Check if the page is posted
           If Page.IsPostBack Then
               Dim m_sWord As String
               m_sWord = Request("txtWord")
               ' #Check if txtWord has a value
               If Not m_sWord = "" Then
                   Dim tRow As New TableRow
                   Dim tCell As New TableCell
                   tCell.Controls.Add(New LiteralControl("Error getting the word you posted"))
               End If
           End If
         End Sub

  5. Add a function called GenImage:

         Public Function GenImage(ByVal sWord As String)
             '#Create the row and cell to hold the image in
             Dim tRow As New TableRow
             Dim tCell As New TableCell
             tCell.Controls.Add(New LiteralControl("<img src='img_gen.aspx?w=' & sWord & '>"))
         End Function

So now you have a page that accepts a word posted to it by itself, and calls a aspx page as an image source. Now that was easy, next the fun part ... drawing :).

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About the author

Ruan Meyer

Ruan Meyer Saudi Arabia

erm, what can I say... not much, 'cept that I like music, nwn, dnd, programming (C, C++, C#, VB) etc. and Jack Daniels... ;) oh yes and girls...

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