VB.Net Countdown timer

Question

Afternoon coding guru's!

I have built an application which runs some code every 60 seconds.

What i'd like to do is show the countdown on the application screen but can't fathom out how to do it!

Can anyone assist me with this please?

Thanks
Simon

Answer 1

This can only be called once. When it reaches zero it starts over.

    Private Sub CountDown()
        Static OnlyOne As New Object
        Static _wait As New Threading.ManualResetEvent(False)
        Static stpw As New Stopwatch
        Static CntDwnFrm As New TimeSpan(0, 0, 60)
        If Threading.Monitor.TryEnter(OnlyOne) Then
            stpw.Restart()
            Dim t As task 'background task
            t = Task.Run(Sub()
                             Do
                                 Do
                                     Me.BeginInvoke(Sub()
                                                        Label1.Text = String.Format("{0:n0}",
                                                                                    (CntDwnFrm - stpw.Elapsed).TotalSeconds)
                                                    End Sub)

                                     If stpw.Elapsed >= CntDwnFrm Then
                                         'blast off
                                         stpw.Restart()
                                     End If
                                 Loop While _wait.WaitOne(1000)
                             Loop
                             Threading.Monitor.Exit(OnlyOne)
                         End Sub)
        End If
    End Sub

Answer 2

You can use a Label like in this sample : How to display a countdown timer
or you can display it in Paint event of the main Form, by refreshing it every second

Answer 3

The following class will give you a countdown (note the required module). Place the class and code module into separate files.

Public Class CountDownTimer
    Implements IDisposable

    Public _stopWatch As New Stopwatch()

    Public TimeChanged As Action
    Public CountDownFinished As Action

    Public ReadOnly Property IsRunning() As Boolean
        Get
            Return timer.Enabled
        End Get
    End Property

    Public Property StepMs() As Double
        Get
            Return timer.Interval
        End Get
        Set
            timer.Interval = value
        End Set
    End Property

    Private ReadOnly timer As New Timer()

    Private _max As TimeSpan = TimeSpan.FromMilliseconds(30000)

    Public ReadOnly Property TimeLeft() As TimeSpan
        Get
            Return If((
                _max.TotalMilliseconds - _stopWatch.ElapsedMilliseconds) > 0, 
                      TimeSpan.FromMilliseconds(_max.TotalMilliseconds - _stopWatch.ElapsedMilliseconds), 
                      TimeSpan.FromMilliseconds(0))
        End Get
    End Property

    Private ReadOnly Property _mustStop() As Boolean
        Get
            Return (_max.TotalMilliseconds - _stopWatch.ElapsedMilliseconds) < 0
        End Get
    End Property

    Public ReadOnly Property TimeLeftInSeconds() As String
        Get
            Return TimeLeft.ToString("ss")
        End Get
    End Property

    Public ReadOnly Property TimeLeftMinutesSecondsMilliSeconds() As String
        Get
            Return TimeLeft.ToString("mm\:ss\.fff")
        End Get
    End Property

    Private Sub TimerTick( sender As Object,  e As EventArgs)

        TimeChanged?.Invoke()

        If _mustStop Then
            CountDownFinished?.Invoke()
            _stopWatch.Stop()
            timer.Enabled = False
        End If

    End Sub
    ''' <summary>
    ''' Setup with minutes and seconds
    ''' </summary>
    ''' <param name="minutes"></param>
    ''' <param name="seconds"></param>
    Public Sub New( minutes As Integer,  seconds As Integer)
        SetTime(minutes, seconds)
        Initialize()
    End Sub
    ''' <summary>
    ''' Setup with TimeSpan
    ''' </summary>
    ''' <param name="ts"><see cref="TimeSpan"/></param>
    Public Sub New(ts As TimeSpan)
        SetTime(ts)
        Initialize()
    End Sub

    Public Sub New()
        Initialize()
    End Sub

    Private Sub Initialize()
        StepMs = 1000
        AddHandler timer.Elapsed, AddressOf TimerTick
    End Sub

    Public Sub SetTime(ts As TimeSpan)
        _max = ts
        TimeChanged?.Invoke()
    End Sub

    Public Sub SetTime(minutes As Integer, Optional seconds As Integer = 0)
        SetTime(TimeSpan.FromSeconds(minutes * 60 + seconds))
    End Sub

    Public Sub Start()
        timer.Start()
        _stopWatch.Start()
    End Sub

    Public Sub Pause()
        timer.Stop()
        _stopWatch.Stop()
    End Sub

    Public Sub [Stop]()
        Reset()
        Pause()
    End Sub

    Public Sub Reset()
        _stopWatch.Reset()
    End Sub

    Public Sub Restart()
        _stopWatch.Reset()
        timer.Start()
    End Sub

    Public Sub Dispose() Implements IDisposable.Dispose
        timer.Dispose()
    End Sub
End Class

Protect against cross threading

Public Module Extensions
    <Runtime.CompilerServices.Extension>
    Public Sub InvokeIfRequired(Of T As ISynchronizeInvoke)( control As T,  action As Action(Of T))
        If control.InvokeRequired Then
            control.Invoke(New Action(Sub() action(control)), Nothing)
        Else
            action(control)
        End If
    End Sub

End Module

Form with one button, one label

Public Class Form1

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

        Label1.Text = "60"

        Dim timer As New CountDownTimer
        timer.SetTime(0, 60)
        timer.Start()

        timer.TimeChanged = New Action(Sub()
            Label1.InvokeIfRequired(Sub(lb)
                Label1.Text = timer.TimeLeftInSeconds
            End Sub)
        End Sub)

        timer.CountDownFinished = New Action(Sub()
            timer.Stop()
            MessageBox.Show("Done")
        End Sub)


    End Sub

End Class

Answer 4

Thanks for all your responses.

I have used the solution recommended by @Dewayne Basnett which works perfectly.

Simon

Answer 5

Hi I am trying to use visual basic to make a bird fly across the window and I want it to do so repeatedly and dont know how to make a timer loop after a set number of ticks does anyone have an idea?

The language I need to use is Windows Forms App (.Net Framework)