Sample Code 467: How to set up a stopwatch accurate to hundredth of a second? |
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Written by kksou
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Wednesday, 02 April 2008 |
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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:
Solution
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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;
}
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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:
- 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.
- Calculate the elapsed time to the hundredth of a second.
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