Question about webbrowser control from another thread

[iamcpc]

I'm trying to set up a situation where outside of a form I can have form1.webbrowser1 start at www.google.com and navigate to www.yahoo.com where the URL before the navigate is www.google.com and after the navigate is www.yahoo.com.

  Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim testthread As New System.Threading.Thread(AddressOf Form1.dowork)
        site1 = "www.yahoo.com"
        Debug.Print(Form1.WebBrowser1.Url.ToString)
        'this shows www.google.com
        testthread.Start()
        System.Threading.Thread.Sleep(3000)
        'System.Windows.Forms.Application.DoEvents()
        System.Threading.Thread.Sleep(3000)
        Debug.Print(Form1.WebBrowser1.Url.ToString)
        'this shows www.google.com
    End Sub

This will navigate the webbrowser from another thread using this code on form1:

    Public Delegate Sub navigatecallback()
    Public Sub navigate()
        If Me.WebBrowser1.InvokeRequired Then
            Me.WebBrowser1.Invoke(New navigatecallback(AddressOf navigate))

        Else
            Me.WebBrowser1.Navigate(site1)
        End If
    End Sub


    Public Sub dowork()
        navigate()
    End Sub

Why is is that, when I step through this, my navigating thread does not start when i testthread.start()?

[dunfiddlin]

Might help if the declared thread delegate (AddressOf Form1.dowork) and the delegate you actually want to call (navigatecallback) were connected in some way.

[iamcpc]

Might help if the declared thread delegate (AddressOf Form1.dowork) and the delegate you actually want to call (navigatecallback) were connected in some way.

How do I connect them? Also how come, when I step through this, the thread starts when I tell it to, but when I run it without stepping through, the thread starts afterwards?

[dunfiddlin]

Sorry, I misread you code and didn't spot the dowork Sub tucked in at the bottom. The delay is caused by your sleep on the main thread which stops all thread activity before the start message has been transmitted. If you're going to sleep the main thread there's really no point in putting the browser navigate on another thread anyway. The whole point of threading is to keep the UI active!

[iamcpc]

Sorry, I misread you code and didn't spot the dowork Sub tucked in at the bottom. The delay is caused by your sleep on the main thread which stops all thread activity before the start message has been transmitted. If you're going to sleep the main thread there's really no point in putting the browser navigate on another thread anyway. The whole point of threading is to keep the UI active!

Is there any way to start a thread, wait a second, and then start another thread? or is there some setting which affects how sleep works?


I have this multithread loop in one of my applications. In this application there is not pause between the thread starts. After the button click event is done it starts all 5 threads at the same time yet on a new application one starts then after 2 seconds another starts.

 Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
        Dim testthread As New System.Threading.Thread(AddressOf Module1.loop3)
        Dim testthread1 As New System.Threading.Thread(AddressOf Module1.loop3)
        Dim testthread2 As New System.Threading.Thread(AddressOf Module1.loop3)
        Dim testthread3 As New System.Threading.Thread(AddressOf Module1.loop3)
        Dim testthread4 As New System.Threading.Thread(AddressOf Module1.loop3)
        testthread.Start(1)
        System.Threading.Thread.Sleep(2000)

        testthread1.Start(2)
        System.Threading.Thread.Sleep(2000)
        testthread2.Start(3)
        System.Threading.Thread.Sleep(2000)
        testthread3.Start(4)
        System.Threading.Thread.Sleep(2000)
        testthread4.Start(5)
        System.Threading.Thread.Sleep(2000)
        Call Module1.loop3(6)

    End Sub

Public Sub loop3(ByVal column As Integer)

        System.Threading.Thread.Sleep(2000)


        If xl.visible <> True Then
            xl.visible = True
        End If



        Try
            If Not xl.activeworkbook.name = "Spenddown IN Mdcd.xlsm" Then
                xl.workbooks.open("C:\Documents and Settings\BMcGuir1\Desktop\Test\spenddown in mdcd.xlsm")
                GoTo done
            End If

        Catch
            xl.workbooks.open("C:\Documents and Settings\BMcGuir1\Desktop\Test\spenddown in mdcd.xlsm")
        End Try

done:






        Dim y As Long
        For y = 1 To 100
            xl.activeworkbook.sheets("sheet1").cells(y, column).value = y
            System.Threading.Thread.Sleep(100)
        Next
        'MsgBox("done")
    End Sub

How some the sleep(2000) works on one application but not another?