Program flow - order of execution.

As a real novice I am writing a small application to measure a persons reaction time by presenting a prompt on screen and then measuring how long before a key is pressed.

My problem is understanding the program flow. When run the form is presented and then when the Start button is pressed there is a short, random delay and the prompt presented. The clock stops when any key is pressed (sub EndTimer) and the time presented - all as expected - but then the prompt is presented again and again and again..... The app works as intended except for the cycling. I do not understand why it is looping. The relavant code follows. I thought it would run through the 2 calls capture the keypress and then stop at the btnStart_Click End Sub.

Private Sub btnStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _

Handles btnStart.Click

Call RandomDelay(1, 2)

Call PromptAndStartTimer()

End Sub

Private Sub RandomDelay(ByVal MinSeconds As Integer, ByVal MaxSeconds As Integer)

Dim Cycles As Double

Dim Pause As Integer

Cycles = (CInt(Int((MaxSeconds * Rnd()) + MinSeconds)))

' Capture milliseconds system been running

Pause = My.Computer.Clock.TickCount

' Waste time for between 1 & 6 seconds

Do While (My.Computer.Clock.TickCount - Pause) < (Cycles * 1000)

Loop

End Sub

Private Sub PromptAndStartTimer()

' QueryPerformanceCounter and QueryPerformanceFrequency.

' Use to provide a high resolution clock.

' Capture Frequecy of Tick in Ticks/second

Call QueryPerformanceFrequency(Frequency)

' Capture StartTick number

Call QueryPerformanceCounter(StartTick)

' and present prompt

tbxPrompt.Text = "Press any letter key now"

End Sub

Private Sub EndTimer(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyEventArgs) _Handles btnStart.KeyDown

'Capture EndTick number

Call QueryPerformanceCounter(EndTick)

' Calculate reaction time

tbxTime.Text = (EndTick - StartTick) / Frequency

tbxPrompt.Text = " "

End Sub

Sorry for such a long post but I wanted to be sure I provided enough information. I have tried looking all over the place for help but have come up with nothing - I am probably not using the right search terms.

Very many thanks in advance for any pointers. Peter.

Answer this question

Program flow - order of execution.

Earl Jr
Thank you!
It works now!
Chandra

A timer calls over and over until you call it's Stop() method.
RUReady
There is a nice stopwatch class in the new framework - easy to use...
I.F. Kruzenshtern

Sorry, I missed that. You may find your answer here:

http://msdn.microsoft.com/library/default.asp url=/library/en-us/dnpag/html/scalenethowto09.asp

as this is sample code that uses those APIs from .NET.
Fernando Stockler
Many thanks for such a quick reply.

Please may I ask you to expand a little on what you have said Are you talking about the
Call QueryPerformanceCounter(EndTick) line I thought I was reading a system variable not starting a timer. Just in case it matters here are the function declarations.

Private Declare Function QueryPerformanceCounter Lib "kernel32" _
(ByRef pcTickCount As Long) As Integer

Private Declare Function QueryPerformanceFrequency Lib "kernel32" _
(ByRef pcFrequency As Long) As Integer

Thanks, Peter
Pramod
Well, I have tried that code,
but I seem to have an overflow error..

Private Sub inbox_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles Inbox.KeyPress

Result = (Now.Ticks - StartInterval) / 10000

tmr.Stop()

tb.Visible = False

Inbox.Text = "Response Latency: " & Result & " Milliseconds."

Inbox.ReadOnly = True

e.Handled = True

End Sub

it says that its an overflow...
This only occurs when I press a key in the text box, just like said in the
Sub inbox_KeyPress...
but why does it happen to be an overflow
How can I fix it

Thank You
Keehun Nam
Terry Field
Wow! Such quick repiles. Many thanks to you all especially ReneeC for taking the time to write a much more elegant piece of code. I will study it and understand it as soon as I can.

As you realise this is part of my learning exercise and, while I will use ReneeC's approach, I would like to try and understand why my effort behaves as it does. So I wonder if someone would be prepared to have a go at explaining where I have gone wrong. It's not just a case of solving this problem but of understanding things a bit better.

Once again thanks for the replies and your forebearance with a real novice.

Peter.
JpFortin

I apologize but there are some usages, that are difficult for me. This program should be TOTALLY event driven.

So I've written a little something. All controls are totally dynamic. Take a clean fresh project and open the editor.

Cntrl-A

Delete - clean the form out totally and then cut and paste this in it and enjoy....

There is NO looping and no waiting on anything.

Imports system

Imports system.math

Public Class Form1

    Protected Friend WithEvents tb As New TextBox

    Protected Friend WithEvents tmr As New Timer

    Protected Friend WithEvents Inbox As New TextBox

    Protected Friend WithEvents cbGo As New Button

    Protected Friend WithEvents cbExit As New Button

    Protected Friend WithEvents cbReset As New Button

    Protected generator As New Random

    Protected StartInterval As New Long

    Protected Result As UInt32

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        init()

        Randomize()

    End Sub

    Private Sub tmr_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles tmr.Tick

        tmr.Stop()

        Inbox.Focus()

        tb.Visible = True

        StartInterval = Now.Ticks

    End Sub

    Private Sub inbox_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles Inbox.KeyPress

        Result = (Now.Ticks - StartInterval) / 10000

        tmr.Stop()

        tb.Visible = False

        Inbox.Text = "Response Latency: " & Result & " Milliseconds."

        Inbox.ReadOnly = True

        e.Handled = True

    End Sub

    Private Sub cbGo_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cbGo.Click

        tb.Visible = False

        cbGo.Enabled = False

        Inbox.Clear()

        tmr.Interval = RandomInterval()

        tmr.Start()

    End Sub

    Private Sub cbReset_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cbReset.Click

        tmr.Stop()

        tb.Visible = False

        cbGo.Enabled = True

        Inbox.ReadOnly = False

        Inbox.Clear()

    End Sub

    Private Function RandomInterval() As Integer

        Const MinInt As Integer = 5000 ' 5 Seconds

        Const MaxInt As Integer = 30000 ' 30 seconds

        Return generator.Next(MinInt, MaxInt)

    End Function



    Private Sub init()

        'Set the controls up dynamically

        Const MeSize As Integer = 300

        Const tbsize As Integer = 30

        Const CntrlRight As Integer = 20

        Dim diff = ((Sqrt((MeSize ^ 2) * 2) - Sqrt((tbsize ^ 2)) * 2) / 2) * 0.707 ' centering

        tb.Size = New Size(tbsize, tbsize)

        tb.BackColor = Color.Teal

        tb.Visible = False

        Me.Size = New Size(MeSize, MeSize + 30)

        Me.Controls.Add(tb)

        tb.Location = New Point(diff, diff)

        cbGo.Text = "Go"

        Me.Controls.Add(cbGo)

        cbGo.Location = New Point(CntrlRight, MeSize - 30)

        cbGo.Width -= 30

       cbExit.Text = "Exit"

        Me.Controls.Add(cbExit)

        cbExit.Size = cbGo.Size

        cbExit.Location = New Point(MeSize - 60, cbGo.Top)

        Me.Controls.Add(Inbox)

        Inbox.AcceptsReturn = True

        Inbox.Location = New Point(CntrlRight, cbGo.Top - Inbox.Height - 10)

        Inbox.Width = MeSize - ((CntrlRight * 2) + 8)

        Me.Controls.Add(cbReset)

        cbReset.Size = cbExit.Size

        cbReset.Text = "Reset"

        cbReset.Location = New Point(cbExit.Left - 50, cbExit.Top)

        tmr.Enabled = True

        tmr.Stop()

    End Sub



    Private Sub cbExit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cbExit.Click

        Me.Close()

    End Sub

End Class
darc

Change this

Protected Result As UInt32

to this

Protected Result As Long
ChristoRaja

Peter,

I hope you do learn from what I wrote.

I believe you program behaves the way it does is what cgraus said, timers are retitiive until stopped. You'll notice that in my code I'm really meticulous about instantly stopping the timer, until I explicity want it to run..
Program flow - order of execution.

Answer this question