[2008] Creating New Forms At RunTime

[perito]

so Im creating an IRC Client.
If someone sends u a private msg, I need to create a new form having 2 textboxes and a Send button
...
how? should I create a form in design time then use a code
dim NEWFORM as NEW FORM2?
if so, how to write in the textbox of a specific form when a msg is recieved?

[visualAd]

You have already suggested the best way of doing it. You create the form at design time then create a new instance of it at runtime. By default the control members are declared as Friend meaning their properties are accessible from within the other forms in the project but not outside the project.

If you want to access it from another project then you can either declare them as Public by modifying the modifier property or the better way would be to have to create a public member on the form e.g: setText() to do it for you.

The example below shows how you might declare an instance of the form and modify the controls before displaying it.

        Dim rt As New frmRuntime

        rt.txtMbr1.Text = "hello"
        rt.txtMbr2.Text = "world"

        rt.Show(Me)

You can also use the ShowDialog method which will prevent the use of the parent form until it is closed; however, as you are creating a PM facility I would imagain you wouldn't need it.

[perito]

no, thats not my question
here:
lets say User Mike Sends a msg to the client
we open a new form
then Mike sends another msg... that code will open a new form!
I dont want to open a new form, i want to check if a form with the text Mike is opened so I can add to it, if not, we open a new form
how to do that?

[perito]

in other words, how to a loop all the already opened forms and check their caption (frm.text)?
if frm.text = new username then add to the text box
else create a new form

[Atheist]

Create a List(Of Form) to hold all the chat forms. When a new message arrives, check to see if a chat is already opened with the sender of the message, if it is you should just call BringToFront method of the form and pass it the new message. If its not opened you create a new instance of the chat form, add it to the list of chat forms, and somehow "tie" it to the sender of the message (Perhaps using the Tag property?)

[visualAd]

I would be inclined to use a hash table containing references to the forms each with an index relating to the name of the user. You can then check the users form exists using the ContainsKey and bring it in to focus accordingly.

Below is some sample code:

Public Class Form1
    Private formTable As Hashtable

    Private Sub btnShow_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnShow.Click
        Dim rt As New frmRuntime

        If formTable.ContainsKey(txtName.Text.ToLower()) Then
            ' give the form focus
            CType(formTable(txtName.Text.ToLower()), _
                        frmRuntime).Activate()
        Else
            rt = New frmRuntime
            rt.Text = txtName.Text
            rt.Show()

            formTable.Add(txtName.Text.ToLower(), rt)
        End If
    End Sub

    Public Sub New()

        ' This call is required by the Windows Form Designer.
        InitializeComponent()

        ' Add any initialization after the InitializeComponent() call.
        formTable = New Hashtable
    End Sub
End Class

[perito]

this is what i got

    Private frmPrivateMsg As New List(Of frmPM)

    Private Sub WritePrivateMsg(ByVal Message As String)
        For Each cc As frmPM In frmPrivateMsg
            If cc.Text = NewUserName Then
                cc.txtMain.AppendText(Message)
                Exit Sub
            End If
        Next
        Dim NewFrm As New frmPM
        NewFrm.Text = NewUserName
        NewUserName = ""
        NewFrm.txtMain.AppendText(Message)
        NewFrm.Show(Me)
        frmPrivateMsg.Add(NewFrm)
    End Sub

Im getting on NewFrm.Show(Me)

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

could u please help?

[visualAd]

This is a totally different problem. What is your AsynhronousClient control and where are you attempting to access it. Have you explicitly created a new thread as a listener for you chat application?

Have a look at this: http://www.developerfusion.co.uk/forums/p/43081/143922/

[perito]

AsynhronousClient is the name of my Class (Class 1) :S
and there are no other classes

[visualAd]

There are the forms as well as the controls. I do believe that your form contains a property which runs an operation in another thread. See what happens when you change the line: NewFrm.Show(Me) to NewFrm.Show().

[perito]

this is weird... it worked, no more errors but
when the form is show .... it freezes
not the whole application, only the new form stops responding...
why?

[Fromethius]

Are you using a listener thread?

[perito]

no,
i connect to irc, i dont need a listener thread

Public Class AsynchronousClient
    Private client As System.Net.Sockets.TcpClient
    Private Const BYTES_TO_READ As Integer = 255
    Private readBuffer(BYTES_TO_READ) As Byte
    Private Delegate Sub WriteText(ByVal text As String)
    Private frmPrivateMsg As New List(Of frmPM)

whats the problem? :S

[Fromethius]

The problem is that you are not using a listener thread. Are you really scanning for incoming messages on the same thread as the one containing all the controls?

[perito]

    Private Sub DoRead(ByVal ar As System.IAsyncResult)
        Dim totalRead As Integer
        Try
            totalRead = client.GetStream.EndRead(ar) 'Ends the reading and returns the number of bytes read.
        Catch ex As Exception
            'The underlying socket have probably been closed OR an error has occured whilst trying to access it, either way, this is where you should remove close all eventuall connections            'to this client and remove it from the list of connected clients.
        End Try
        If totalRead > 0 Then
            'the readBuffer array will contain everything read from the client
            Dim receivedString As String = System.Text.Encoding.UTF8.GetString(readBuffer, 0, totalRead)
            MessageReceived(receivedString)
        End If
        Try
            client.GetStream.BeginRead(readBuffer, 0, BYTES_TO_READ, AddressOf DoRead, Nothing) 'Begin the reading again.
        Catch ex As Exception
            'The underlying socket have probably been closed OR an error has occured whilst trying to access it, either way, this is where you should remove close all eventuall connections                'to this client and remove it from the list of connected clients.
        End Try
    End Sub

the code works fine,
Ive used it alot... is there a problem here?

[visualAd]

I may be wrong: but I believe that when data is received on a port a new thread is spawned which continues to listen in the background. So it is entirely possible that when you attempt to access the members in the current thread that exception will be raised.

[Atheist]

I believe that you may need to invoke to the main thread before creating and showing the form. the doRead method is running on a separate thread so creating and displaying a form from it will not work as its already busy with a tight loop.