#include <QApplication>
#include <QWidget>
#include <QPushButton>
#include <QTimer>
#include <QDebug>
#include <QBoxLayout>

class MainWindow : public QWidget {
  Q_OBJECT
  int cnt = 0;
  QTimer *tmr = 0;
public:
  explicit MainWindow (QWidget *parent = 0): QWidget (parent) {
    QHBoxLayout *layout = new QHBoxLayout (this);
    QPushButton *pb = new QPushButton (this);
    layout->addWidget (pb);

    connect (pb, SIGNAL(clicked()), this, SLOT(initTimer()));
  }

public slots:
  void initTimer (void) {
    cnt=5;
    if (!tmr) {
      tmr = new QTimer(this);
      connect (tmr, SIGNAL(timeout()), this, SLOT(updateCnt()));
    }
    tmr->start (1000);
  }

  void updateCnt (void) {
    qDebug () << __func__ << ": cnt is " << cnt;
    cnt--;
    if (cnt == 0) {
        qDebug () << __func__ << ": deleting timer";
      tmr->stop ();
      delete tmr;
    }
  }
};

int main (int argc, char *argv[]) {
  QApplication a(argc, argv);
  MainWindow mv;

  mv.show ();
  return a.exec();
}

#include "main.moc"