[QT] timer

1 The first way

（1） Using events void timerEvent ( QTimerEvent * ev)
（2） Start timer startTimer( 1000) Millisecond unit
（3）timerEvent The return value of is the unique identifier of the timer You can talk to ev->timerid compare

demand ： Set two timers , Time is different .

（1） The first is rewriting timerEvent function

Add... Here UI Of label Control

  rewrite

//  Timer event 
void Widget::timerEvent(QTimerEvent *event) {
    if (event->timerId() == this->m_Id1) {
        static int num = 1;
        ui->label->setText(QString::number(num++));
    } else if (event->timerId() == this->m_Id2){
        static int num2 = 1;
        ui->label_2->setText(QString::number(num2++));
    }

}

（2） Because there are two timers , Add member attributes to the class , Each represents the return value of two timers

（3） Start two timers

//  Start timer 
this->m_Id1 = startTimer(1000);     //  millisecond 

this->m_Id2 = startTimer(2000);

（4） effect

2  The second way

Timer class

//  Timer class 
QTimer* timer = new QTimer(this);
timer->start(500);       //  In milliseconds 
//  Monitor the signal of timer object 
connect(timer, &QTimer::timeout, this, [=](){
    static int num3 = 1;
    ui->label_3->setText(QString::number(num3++));
});

effect

expand , Click the pause button , The timer pauses

add to QPushbutton Button , Use connect Make connections

//  Click pause , Implementation stop 
connect(ui->btn_pause, &QPushButton::clicked, this, [=](){
    timer->stop();
});

effect