Archived:QTimer example

Comments

HI,

I am added the zip source  code and the image, please have a look to check the accuracy.

--somnathbanik 18:16, 23 May 2011 (EEST)

Log in or Join to leave comments.

Archived: This article is archived because it is not considered relevant for third-party developers creating commercial solutions today. If you think this article is still relevant, let us know by adding the template {{ReviewForRemovalFromArchive|user=~~~~|write your reason here}}.

Qt Quick should be used for all UI development on mobile devices. The approach described in this article (using C++ for the Qt app UI) is deprecated.

This article demonstrates how to use QTimer to trigger events. The demonstration app has a a number of buttons: when the timer expires we call setStyleSheet() and setProperty() on the buttons to change their appearance.

Article Metadata

---

Code Example

Source file: Media:Window.zip

---

Article

Created: divanov (11 Jun 2010)

Last edited: hamishwillee (11 Oct 2012)

Main Class Implementation

#include <QtGui>
#include "window.h"
 
int main (int argc, char **argv)
{
    QApplication app(argc, argv);
 
    Window win;
    win.show();
 
    return app.exec();
}

Window Class Definition

#ifndef WINDOW_H
#define WINDOW_H
 
#include <QtGui>
 
#define NUM_OF_BUTTONS 50
 
class Window : public QMainWindow
{
    Q_OBJECT
 
public:
    Window(QWidget *parent=0);
 
private slots:
    void buttonClicked(bool checked = false);
    void timerTimeout();
 
private:
    QPushButton *buttons[NUM_OF_BUTTONS];
    QTimer *timer;
    int timerCount;
};
 
#endif //WINDOW_H

When user press the button, timer started and will emit timeout() signal every second until 10 events will be produced or another button will be pressed

Window Class Implementation

#include "window.h"
 
Window::Window(QWidget *parent)
    : QMainWindow(parent), timerCount(0)
{
    QGridLayout *layout = new QGridLayout;
    for (int i = 0; i < 10; ++i)
        for (int j = 0; j < 5; ++j) {
            buttons[i * 5 + j] = new QPushButton("Button");
            buttons[i * 5 + j]->setFocusPolicy(Qt::NoFocus);
            layout->addWidget(buttons[i * 5 + j], i, j);
            connect(buttons[i * 5 + j], SIGNAL(clicked(bool)), this, SLOT(buttonClicked(bool)));
        }
 
    QWidget *w = new QWidget;
    w->setLayout(layout);
 
    setCentralWidget(w);
 
    timer = new QTimer(this);
    timer->setInterval(1000);
    connect(timer, SIGNAL(timeout()), this, SLOT(timerTimeout()));
}
 
void Window::buttonClicked(bool checked)
{
    Q_UNUSED(checked);
 
    timerCount = 10;
    if (!timer->isActive())
        timer->start();
}
 
void Window::timerTimeout()
{
    --timerCount;
    if (timerCount <= 0)
        timer->stop();
 
    int idx = (qrand() % 50);
    if (!buttons[idx]->property("coloured").isValid()) {
        buttons[idx]->setStyleSheet("background-color: rgb(0, 255, 0); color: rgb(255, 255, 255)");
        buttons[idx]->setProperty("coloured", true);
    } else {
        buttons[idx]->setStyleSheet("");
        buttons[idx]->setProperty("coloured", QVariant());
    }
}

when the timer expires it emit timerTimeout() slot which changes the property of the button.

Source Code

The full source code presented in this article is available here File:Window.zip