Use of timer and setting timer in code

Question

how do I

Answer 1

Hi,

 There are several examples and tutorials on the net for using a Timer. Take a look at the link below.   8)

Example of the timer control in VB.net

 

 Here is the msdn link to the Timer class that you can use to learn a little about the Methods, Properties, and Events of a Timer.

Timer Class

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If you say it can`t be done then i`ll try it

Answer 2

There are several types of timer and there are many things you might want to do with a timer. Here is a simple example.

• Create a Windows forms project.
• In the forms designer, drag a Timer onto the form from the Components section of the toolbox.
• Change the timer's name property to MyTimer.
• Double-click on the timer in the designer. You will be taken to the code window and a Click Event handler will be created.
• Change the forms class to look like this.

Option Strict On
Option Explicit On

Public Class Form1

    Private counter As Integer = 0

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        MyTimer.Interval = 1000 '1 second
        MyTimer.Start()
    End Sub

    Private Sub MyTimer_Tick(sender As Object, e As EventArgs) Handles MyTimer.Tick
        counter += 1
        Me.Text = counter.ToString
        If counter > 10 Then MyTimer.Stop()
    End Sub
End Class

If you run this application, the form's load event sets the timer's interval to 1000 ms (1 second) and starts the timer. Every second, the timer's Tick event is fired and the Tick event handler increments a counter and displays the value in the form's header. When the counter exceeds 10, the timer is stopped.

Answer 3

how do I

Additionally, you might find this article interesting. It compares the various types of timers available in dotNET.

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Still lost in code, just at a little higher level.

:-)

Answer 4

Hello,

What follows demonstration is a bit more advance but thought it prudent to show.

The following example uses a timer in a class project called from a windows form project. Please note "as is" this will only work if you are targeting Framework 4.5 because Task-based Asynchronous Pattern (TAP) methods used in tangent with the timer.

Form code

First button has no cancel while the second button provides a method to cancel

Public Class Form1
    Private Sub cmdExecute_Click(sender As Object, e As EventArgs) Handles cmdExecute1.Click
        Dim r As New RunnerOne(CInt(nudMilliSeconds.Value), Label1)
        r.Execute()
    End Sub
    ''' <summary>
    ''' Declared at form level so we can perform a cancellation
    ''' </summary>
    ''' <remarks></remarks>
    Private TheRunner As New RunnerTwo
    Private Async Sub cmdExecute2_Click(sender As Object, e As EventArgs) Handles cmdExecute2.Click
        cmdExecute2.Enabled = False
        Await TheRunner.Execute(20, CInt(nudMilliSeconds.Value), CInt(nudMilliSeconds.Value))
        cmdExecute2.Enabled = True
    End Sub
    Private Sub cmdCancel_Click(sender As Object, e As EventArgs) Handles cmdCancel.Click
        TheRunner.TimerStop()
        cmdExecute2.Enabled = True
    End Sub
End Class

Class project code

Public Class StateInformation
    Public Iterator As Integer
    Public Timer As System.Threading.Timer
    Public TimerCanceled As Boolean
End Class

 

Meat and potatoes which implements the timer

''' <summary>
''' There are two different timers demo'd here.
''' No import statements where used as w/i import
''' statements things are clearer.
''' </summary>
''' <remarks></remarks>
Public Class RunnerOne
    Public Property Timer As System.Timers.Timer
    Public Property MilliSecondsInterval As Integer

    Private mCounter As Integer = 0
    Private Label As System.Windows.Forms.Label

    Public Sub New(ByVal MilliSecondsInterval As Integer)
        Me.Timer = New System.Timers.Timer
        Me.MilliSecondsInterval = MilliSecondsInterval
        AddHandler Me.Timer.Elapsed, AddressOf tt_Elapsed
    End Sub
    Public Sub New(ByVal Interval As Integer, ByVal Label As System.Windows.Forms.Label)
        Me.Timer = New System.Timers.Timer
        Me.MilliSecondsInterval = Interval
        Me.Label = Label
        AddHandler Me.Timer.Elapsed, AddressOf tt_Elapsed
    End Sub
    Public Async Function Execute() As Task
        Me.Timer.Start()
        Await Task.Delay(Me.MilliSecondsInterval)
        Me.Timer.Stop()

        Me.Timer.Start()
        Await Task.Delay(Me.MilliSecondsInterval)
        Me.Timer.Stop()

        Me.Timer.Dispose() ' permanently stop timer

        Me.Label.BeginInvoke(New Action(Sub() Me.Label.Text = "Total iterations: " & mCounter.ToString))
    End Function
    Private Sub tt_Elapsed(sender As Object, e As System.Timers.ElapsedEventArgs)
        mCounter += 1
        Me.Label.BeginInvoke(New Action(Sub() Me.Label.Text = mCounter.ToString))
    End Sub
End Class
Public Class RunnerTwo
    Public Property Timer As System.Threading.Timer
    Private StateInfo As New StateInformation

    Public Sub New()
    End Sub
    Public Async Function TimerStop() As Task
        Await Task.Delay(500)
        If Not StateInfo.TimerCanceled Then
            Timer.Change(System.Threading.Timeout.Infinite, System.Threading.Timeout.Infinite)
            StateInfo.TimerCanceled = True
            Console.WriteLine("Stopped, did not complete as per request")
        Else
            Console.WriteLine("To late, already done")
        End If
    End Function
    Public Async Function Execute(ByVal Iterations As Integer, ByVal MilliSeconds As Integer, ByVal Delay As Integer) As Task
        StateInfo = New StateInformation
        StateInfo.TimerCanceled = False
        StateInfo.Iterator = 1

        Dim TimerDelegate As New System.Threading.TimerCallback(AddressOf TimerTask)
        Me.Timer = New System.Threading.Timer(TimerDelegate, StateInfo, MilliSeconds, MilliSeconds)

        StateInfo.Timer = Timer

        While StateInfo.Iterator < Iterations
            Console.WriteLine("Iteration {0} of {1}", StateInfo.Iterator, Iterations)
            Await Task.Delay(Delay)
            If StateInfo.TimerCanceled Then
                Exit While
            End If
        End While

        ' Request Dispose of the timer object.
        StateInfo.TimerCanceled = True

    End Function
    Private Sub TimerTask(ByVal sender As Object)
        Dim State As StateInformation = CType(StateInfo, StateInformation)

        System.Threading.Interlocked.Increment(State.Iterator)
        Console.WriteLine("Launched new thread  " & Now.ToString)

        If State.TimerCanceled Then
            State.Timer.Dispose()
            Console.WriteLine("Done  " & Now)
        End If
    End Sub
End Class

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Answer 5

how do I

Susan 7 of 9

A System.Windows.Forms timer is set to an interval for the code in the timer event to perform whatever it does.

The timers interval can be set at any time via code.

If the timer is already running when the interval is set to a new interval the new interval will not take effect until after the next time the timer event fires unless the timer is stopped and started which will cause it to use the new interval immediately.

A timers time counter is not accurate as other system processes running in a multitasking OS may run something that causes the timers counter to be bumped for some interval until it starts counting again. Probably nano or microseconds at a time but it alters the accuracy of the timers counter.

When the timers event handler fires at the end of its interval whatever code is in the timers event sub runs. However long it takes that code to finish the timers counter does not run again until that code is done.

Here's a simple example of two timers being used to move labels in panels. It makes it look like scrolling text. I have to move them at 6 pixels at a time instead of 1 pixel at a time which is much smoother in order to create the animated .Gif so it would be small enough to post here.

Option Strict On

Public Class Form1

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        Panel1.BorderStyle = BorderStyle.Fixed3D
        Panel1.BackColor = Color.White
        Panel1.Size = New Size(232, 27)
        Panel1.Left = CInt((Me.ClientRectangle.Width / 2) - (Panel1.Width / 2))

        Panel2.BorderStyle = BorderStyle.Fixed3D
        Panel2.BackColor = Color.White
        Panel2.Size = New Size(232, 27)
        Panel2.Left = CInt((Me.ClientRectangle.Width / 2) - (Panel1.Width / 2))

        Label1.Font = New Font("Book Antiqua", 14)
        Label1.Text = "This text scrolls from right to left."
        Label1.Left = Panel1.Width

        Label2.Font = New Font("Book Antiqua", 14)
        Label2.Text = "This text scrolls from left to right."
        Label2.Left = Panel2.Width

        Timer1.Interval = 10
        Timer2.Interval = 10

        Timer1.Start()
        Timer2.Start()

    End Sub

    Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
        Label1.Left -= 6
        If Label1.Left + Label1.Width < 0 Then
            Label1.Left = Panel1.Width
        End If
    End Sub

    Private Sub Timer2_Tick(sender As Object, e As EventArgs) Handles Timer2.Tick
        If Label2.Left > Panel2.Width Then
            Label2.Left = -Label2.Width
        End If
        Label2.Left = Label2.Left + 6
    End Sub

End Class

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La vida loca