Updating DataGrid from other thread

[kejpa]

Hi,

this has surely been asked many times but I can't find the appropriate thread... Sorry :(

 

I have a datatable that gets updated from a separate timer thread.

I want to see the current records of the datatable in a datagrid on a test form of mine. But when the timer has elapsed and the table is updated I get an error that the grid is not updated from the form thread.

 

plz help me....

 

TIA

/Kejpa

[kejpa]

Hey there,

new day, new possibilities... To make errors? ;)

 

So, I've done an extensive search.... and found the answer!

(Sing of happiness sing of Joy, I was here before Killroy...)

Use Invoke

Dozens of places, all the same Use Invoke

Soooo, I did and it failed.

Back on the same spot again.

 

Can anyone help me out here?

I'm posting my test code, a form with a datagrid and a button. The button starts the damn thingy. :)

Public Class Form2
   Private oRnd As cRandomizer
   Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
       oRnd = New cRandomizer
       AddHandler oRnd.NewData, AddressOf UpdateDatagrid
   End Sub

   Private Sub UpdateDatagrid(ByVal dt As DataTable)
       Dim arg As Object = dt
       DataGrid1.BeginInvoke(New UpdateGrid(AddressOf UpdateDG), arg)
   End Sub

   Private Delegate Sub UpdateGrid(ByVal dt As DataTable)
   Private Sub UpdateDG(ByVal dt As DataTable)
       DataGrid1.DataSource = dt
   End Sub
End Class
Friend Class cRandomizer
   Private trdmodRandomMaker As Threading.Thread
   Private fmodAlive As Boolean
   Private dtmodRandom As DataTable

   Public Event NewData(ByVal dt As DataTable)
   Public Sub New()
       Dim dr As DataRow
       Dim i as Integer

       dtmodRandom = New DataTable
       dtmodRandom.Columns.Add(New DataColumn("Number", GetType(System.Int32)))
       dtmodRandom.Columns.Add(New DataColumn("Frequency", GetType(System.Int32)))
       For i = 1 To 10
           dr = dtmodRandom.NewRow
           dr(0) = i
           dr(1) = 0
           dtmodRandom.Rows.Add(dr)
       Next
       dtmodRandom.AcceptChanges()

       fmodAlive = True
       trdmodRandomMaker = New Threading.Thread(AddressOf RandomMaker)
       trdmodRandomMaker.Start()

   End Sub

   Private Sub RandomMaker()
       Dim iNumber As Integer

       Do While fmodAlive
           Threading.Thread.Sleep(1000)
           iNumber = CInt(10 * Rnd()) + 1
           dtmodRandom.Rows(iNumber)(1) = CInt(dtmodRandom.Rows(iNumber)(1)) + 1
           RaiseEvent NewData(dtmodRandom)
       Loop
   End Sub

   Protected Overrides Sub Finalize()
       fmodAlive = False
       trdmodRandomMaker = Nothing
       MyBase.Finalize()
   End Sub
End Class

 

ANY help appreciated!

Regards

/Kejpa

 

edit: Alright, guilty. I am using VB2005, and it obviously doesn't work like .NET 1.1....

Edited December 14, 2004 by kejpa