Question

I have a windows form application that will open other forms, but will only display the forms for a few seconds (user configurable). I would normally do something like threading.thread.sleep(n), however when doing this the forms controls do not load only the white background shows, and I have also been reading that this isnt the best practice for what I am after as user input will not be actioned until the thread wakes up.

I have come across people using System.Timers.Timer(n), but I am struggling to get this to work for me, the form will only open and close straight away (you can only see a flash as the form opens then closes).

The code that I am using is:

Private Shared tmr As New System.Timers.Timer    
aForm.Show()
tmr = New System.Timers.Timer(aSleep * 60 * 60)
tmr.Enabled = True

aForm.Close()

This is all contained within a Private sub that passes the form and the defined run time.

My intention is to have the main application running from the task bar, which then calls one of the forms that will display for a defined period of time, close the form, then call another one of the forms.

Is any able to point me in the right direction for why the form opens then closes without seeing through the defined run time (I have been testing with 10 seconds), or is there a better way of doing what I am seeking?

Your help is greatly appreciated.

Matt

Answer 1

the docs say there’s an Elapsed event handler that gets called when the time elapses. You would close the form in the handler:

http://msdn.microsoft.com/en-us/library/system.timers.timer%28VS.85%29.aspx

I just wrote a little example that shows what you would need to do at:

http://www.antiyes.com/close-form-after-10-seconds

Below is the relevant code, the full solution can be downloaded from the article.

Form 1 code

Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim frm2 As New Form2()
        frm2.ShowDialog()
    End Sub

End Class

Form 2 code

Imports System.Timers

Public Class Form2

    Protected Overrides Sub OnLoad(ByVal e As System.EventArgs)
        MyBase.OnLoad(e)
        Dim tmr As New System.Timers.Timer()
        tmr.Interval = 5000
        tmr.Enabled = True
        tmr.Start()
        AddHandler tmr.Elapsed, AddressOf OnTimedEvent
    End Sub

    Private Delegate Sub CloseFormCallback()

    Private Sub CloseForm()
        If InvokeRequired Then
            Dim d As New CloseFormCallback(AddressOf CloseForm)
            Invoke(d, Nothing)
        Else
            Close()
        End If
    End Sub

    Private Sub OnTimedEvent(ByVal sender As Object, ByVal e As ElapsedEventArgs)
        CloseForm()
    End Sub

End Class

Of course for this code to work you’d need forms setup with the buttons.