467. How to set up a stopwatch accurate to hundredth of a second?

Problem

The method we've used in How to set up a countdown timer - Part 3 - accurate to hundredth of a second? allows us to set up a stopwatch accurate to a hundredth of a second as shown below:

How to set up a stopwatch accurate to hundredth of a second?


Solution


Sample Code

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<?php
$window = new GtkWindow();
$window->set_title($argv[0]);
$window->set_size_request(400, 200);
$window->connect_simple('destroy', array('Gtk','main_quit'));
$window->add($vbox = new GtkVBox());

// display title
$title = new GtkLabel("Stopwatch accurate to a hundredth of a second");
$title->modify_font(new PangoFontDescription("Times New Roman Italic 10"));
$title->modify_fg(Gtk::STATE_NORMAL, GdkColor::parse("#0000ff"));
$title->set_size_request(-1, 40);
$vbox->pack_start($title, 0);
$vbox->pack_start(new GtkLabel(), 0);

$vbox->pack_start(new GtkLabel('Click the button to start.'), 0);
$vbox->pack_start(new GtkLabel('Click again to stop.'), 0);
$vbox->pack_start(new GtkLabel(), 0, 0);

$vbox->pack_start($hbox = new GtkHBox(), 0, 0);
$hbox->pack_start($button = new GtkButton('Start'), 1, 0);
$vbox->pack_start(new GtkLabel());
$button->connect('clicked', 'on_button');

$progress = new GtkLabel();
$progress->modify_font(new PangoFontDescription("Times New Roman Italic 20"));
$vbox->pack_start($progress);

$window->show_all();
Gtk::main();

function on_button($button) {
    global $timeout_ID;
    if ($button->get_label() == 'Start') {
        global $start_time;
        $start_time = microtime(1);
        $timeout_ID = Gtk::timeout_add(1, 'process_task'); // note 1
        $button->set_label('Stop');
    } else {
        Gtk::timeout_remove($timeout_ID);
        $button->set_label('Start');
        return false;
    }
}

function process_task() {
    global $start_time;
    $elapsed_time = microtime(1) - $start_time;

    $elapsed_time_min = intval($elapsed_time / 60);
    $elapsed_time_sec = $elapsed_time % 60;
    $elapsed_time_hsec = $elapsed_time - intval($elapsed_time);
    $elapsed_time_hsec = round($elapsed_time_hsec * 100);
    $elapsed_time_hsec = str_pad($elapsed_time_hsec, 2, STR_PAD_LEFT, '0'); // note 2
    global $progress;
    $progress->set_text(date('i:s', $elapsed_time). '.' . $elapsed_time_hsec);
    while (Gtk::events_pending()) {Gtk::main_iteration();}

    return true;
}

?>

Output

As shown above.
 

Explanation

The above code is based on How to set up a countdown timer - Part 3 - accurate to hundredth of a second?

What's new here:

  1. Note that I set the timeout event at 1 order magnitude higher, i.e. at 1ms interval. This is because I feel the timeout event may get delayed sometimes if the system is busy or the event queue is long. If the stopwatch were to be accurate to a hundredth of a second, it's better to set the timeout event an order of magnitude higher than the desired accuracy.
  2. Calculate the elapsed time to the hundredth of a second.

Related Links

Comments   

0 # emilce 2015-05-12 09:56
hello! I'm from Argentinian.
A question: can I add var hours? in the example only is seconds and minutes. I want hours!..

Thanks,
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