[2005] Showing another form

I have a loading form that i want to show when i'm reading something from the serial port. My only problem is that i'm not 100% sure what's with the new stuff like delegates, but i've got it to work with a MyDelegate sub. But to invoke on the loading form, it throws an exception that the window needs a handle before you can invoke... So if I make it visible and then hide it again in the main form load, it works... Any ideas how i could avoid the flicker of the form showing and hiding and how it actually should be done? :D

Thanks

Can't you just call the show and hide method?
Form1.Show()
Form1.Hide()

Here is what i have so far... Any comments would be useful :)

There is no need to call the visible properties in the for load.
Just change you Show and Hide functions to call

VB Code:

Private Sub ShowRead()
        fRead.Show()
    End Sub
 
    Private Sub HideRead()
        fRead.Hide()
    End Sub
 
    Private Sub Form_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        If Serial.IsOpen = True Then
            Serial.Close()
        End If
 
        Index = 0
 
        fRead.pbRead.Minimum = 0
        fRead.pbRead.Maximum = 63
        fRead.pbRead.Value = 0
 
        Try
            With Serial
                .BaudRate = 9600
                .Parity = IO.Ports.Parity.None
                .DataBits = 8
                .StopBits = IO.Ports.StopBits.One
            End With
            Serial.Open()
        Catch ex As Exception
            MsgBox(ex.ToString)
        End Try
    End Sub

I get an exception :

Invoke or BeginInvoke cannot be called on a control until the window handle has been created.

on this line :

fRead.Invoke(New myDelegate(AddressOf ShowRead))

Question, why are you using delegates to show the form? Why not just call the show method in your DataRecieved sub like so

VB Code:

Private Sub DataReceived( _
       ByVal sender As Object, _
       ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) _
       Handles Serial.DataReceived
 
        If fRead.Visible = False Then
            fRead.Show()
        End If
 
        fRead.pbRead.Invoke(New myDelegate(AddressOf ChangePB))
 
        Tdata(Index) = Serial.ReadByte
        Index += 1
 
        If Index = 64 Then
            Index = 0
 
            Call Display()
        End If
    End Sub

Cross-thread operation not valid: Control 'frmRead' accessed from a thread other than the thread it was created on.

Have I worded it wrong? I can't be the first to run into this, can I? :)

Someone? Anyone? Please? :(

Please? :cry:

Here is something similiar out of an application that I have done.

My ShowProcessing.vb class

Code:

---

Imports System.ComponentModel

Public Class ShowProcessing
    Implements IDisposable

    Private _TextToDisplay As String
    Private WithEvents _bw As New BackgroundWorker

#Region " IDisposable Support "
    Private disposedValue As Boolean = False        ' To detect redundant calls

    ' IDisposable
    Protected Overridable Sub Dispose(ByVal disposing As Boolean)
        If Not Me.disposedValue Then
            If disposing Then

            End If

            _bw.Dispose()
        End If
        Me.disposedValue = True
    End Sub
    ' This code added by Visual Basic to correctly implement the disposable pattern.
    Public Sub Dispose() Implements IDisposable.Dispose
        ' Do not change this code.  Put cleanup code in Dispose(ByVal disposing As Boolean) above.
        Dispose(True)
        GC.SuppressFinalize(Me)
    End Sub
#End Region

#Region " Property Declarations "
    Friend Property TextToDisplay() As String
        Get
            Return _TextToDisplay
        End Get
        Set(ByVal value As String)
            _TextToDisplay = value
        End Set
    End Property
#End Region

    Public Sub New()
        _bw.WorkerSupportsCancellation = True
    End Sub

    Friend Sub StartProcessing()
        _bw.RunWorkerAsync()
    End Sub

    Friend Sub StopProcessing()
        _bw.CancelAsync()
    End Sub

    Private Sub _bw_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles _bw.DoWork
        Dim worker As BackgroundWorker = CType(sender, BackgroundWorker)

        e.Result = DisplayForm(worker, _TextToDisplay, e)
    End Sub

    Private Function DisplayForm(ByVal worker As BackgroundWorker, ByVal inText As String, ByVal e As System.ComponentModel.DoWorkEventArgs) As Boolean
        Dim frm As New frmProcessing

        With frm
            .Text = inText
            .ShowDialog(worker, e)
            .Dispose()
        End With
    End Function
End Class

---

My ProgressBar form:

Code:

---

Public Class frmProcessing

    Private _worker As System.ComponentModel.BackgroundWorker
    Private _e As System.ComponentModel.DoWorkEventArgs

    Private Sub frmProcessing_FormClosed(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosedEventArgs) Handles Me.FormClosed
        _e.Cancel = True
    End Sub

    Private Sub frmProcessing_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load
        With ProgressBar1
            .Minimum = 0
            .Maximum = 100
            .Value = 0
        End With

        With Timer1
            .Interval = 500
            .Start()
        End With

        Cursor = Cursors.WaitCursor

    End Sub

    Private Sub Timer1_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        If _worker.CancellationPending Then
            Me.Close()
        End If

        If ProgressBar1.Value = 100 Then
            ProgressBar1.Value = 0
        Else
            ProgressBar1.Value += 1
        End If
    End Sub

    Public Overloads Function ShowDialog(ByVal worker As System.ComponentModel.BackgroundWorker, ByVal e As System.ComponentModel.DoWorkEventArgs) As System.Windows.Forms.DialogResult
        _worker = worker
        _e = e
        MyBase.ShowDialog()
    End Function
End Class

---

The example above is shown by FormA when it starts a SQL Stored Procedure that takes about 5 minutes to run. I just wanted the user to understand that it was still working.

That should give you a push in the right direction.

PS - Why all of the Delegates in your code? Is there something I am missing?

I had the Delegates, so I could change the values of the label and the progressbar without getting the errors I've written above (Cross-thread operation not valid) :( I might be going about this the wrong way... I'll look at your code, try and compare. So thanks, I'll have a look :)