Timer is working if code is inside botton_click event handler, but it does not if it is inside method

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Hi guys,
I have an application using timer. The timer works fine when I put the timer code inside the botton_click event hundler, but it doesnt work if the timer code is inside a methode for example. Any body can help me why is that. Thank you.
The timer code is:

C#

DateTime startTime, StopTime;
TimeSpan stoppedTime;
bool reset;
private void startMethod()
{   tmDisplay.Enabled = true;
    // Reset display to zero
    reset = true;
    lblElapsed.Text = "00:00.00.0";
    // Start timer and get starting time
    if (reset)
    {
        reset = false;
        startTime = DateTime.Now;
        stoppedTime = new TimeSpan(0);
    }
    else
    {
        stoppedTime += DateTime.Now - StopTime;
    }
}
private void tmDisplay_Tick(object sender, EventArgs e)
{
    DateTime currentTime;
    //Determine Ellapsed Time
    currentTime = DateTime.Now;
    // Display Time
    lblElapsed.Text = HMS(currentTime - startTime - stoppedTime);

}
private string HMS(TimeSpan tms)
{
    //format time as string; leaving off last six decimal places
    string s = tms.ToString();
    return (s.Substring(0, s.Length - 6));
}

[edit]Code block switched to C# from CSS - OriginalGriff[/edit]

Posted 28-Jul-11 9:22am

Basim 2

Updated 28-Jul-11 9:39am

OriginalGriff

v4

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Philippe Mori · Answer 1 · 2011-07-28T14:23:00

The timer and computation should works in a function or an event handler. When you say, it does not works, is it that the text is not updated?

You have to remember that timer and screen refreshing are both low priority. Thus if you make a tight loop and the CPU is in use, nothing will be refreshed during that time.

If you want to update the screen while doing an intensive algorithm, you should look to uses a BackgroundWorker and update the UI every now and then (say every 1/10 of a second).

I don't see any other reason why it would not works (other than the UI thread being busy 100% of the time). But provided code does not give us the full context.

Now for your code:

1) reset is set to true before being tested.

2) Why not initialize currentTime at the declaration:

DateTime currentTime = DateTime.Now

Or even use DateTime.Now in the expression since the value is not reused elsewhere.

lblElapsed.Text = HMS(DateTime.Now - startTime - stoppedTime);

3) The previous code is incorrect when the timer is in stopped state. Well, I guess that tmDisplay would be disabled in that case... but then would the label be updated when the timer is stopped. If so, then the code in tmDisplay_Tick should call a function UpdateElapsedTime() to avoid code duplication.

C#

private void tmDisplay_Tick(object sender, EventArgs e)
{
    UpdateElapsedTime();
}

private void UpdateElapsedTime()
{
    lblElapsed.Text = HMS(DateTime.Now - startTime - stoppedTime);
}

That way, UpdatedElapsedTime() can be called the the timer is stopped.

4) HMS function does not properly work when elapsed time fall exactly on a whole second since TimeSpan.ToString() won't display the 0 in that case.

5) Once the previous code fixed, someone would typically use HMS function at reset time to ensure that proper formating is used even if HMS function is modified.

C#

lblElapsed.Text = HMS(nw TimeSpan());

Even now, it look like an extra decimal was displayed initially...

6) I think that your HMS function would keep the final dot and thus it should probably be s.Length - 7. But you code would be better if you would remove everything from the last decimal separator (included). Windows provide that information.

If you are using .NET 4.0, then you can use new formatting options:

TimeSpan.ToString()[^]

Custom TimeSpan Format String[^]