Qt5.9 C++开发指南 4.4 定时器和计时器的使用（人生时间浪费器）

用到了定时器和计时器，定时器发出timeout()信号，就更新lcdnumber上的数值。

#include "dialog.h"
#include "ui_dialog.h"

Dialog::Dialog(QWidget *parent)
    : QDialog(parent)
    , ui(new Ui::Dialog)
{
    
    
    ui->setupUi(this);

    fTimer = new QTimer(this);
    fTimer->stop();
    fTimer->setInterval(100);//设置定时周期  毫秒
    connect(fTimer, SIGNAL(timeout()),this, SLOT(on_timer_timeOut()));
}

Dialog::~Dialog()
{
    
    
    delete ui;
}

void Dialog::on_timer_timeOut()
{
    
    
    value++;
    if(value>100)
        value = 0;
    ui->lcdNumber->display(value);
    ui->progressBar->setValue(value);
}


void Dialog::on_BtnStart_clicked()
{
    
    
    fTimer->start();
    fTimeCounter.start();
}

void Dialog::on_BtnStop_clicked()
{
    
    
    fTimer->stop();
    int msec = fTimeCounter.elapsed();
    int ms = msec%1000;
    int sec = msec/1000;

    QString str = QString::asprintf("%d sec %d ms",sec,ms);

    ui->label_Time->setText(str);
}


void Dialog::on_BtnRestart_clicked()
{
    
    
    value = 0;
    ui->lcdNumber->display(value);
    ui->progressBar->setValue(value);
}

#ifndef DIALOG_H
#define DIALOG_H

#include <QDialog>
#include <QTime>
#include <QTimer>
QT_BEGIN_NAMESPACE
namespace Ui {
    
     class Dialog; }
QT_END_NAMESPACE

class Dialog : public QDialog
{
    
    
    Q_OBJECT

public:
    Dialog(QWidget *parent = nullptr);
    ~Dialog();

private:
    Ui::Dialog *ui;

    QTimer *fTimer; //定时器
    QTime fTimeCounter;//计时器
    int value = 0;//计数
private slots:
    void on_timer_timeOut();//定时器溢出处理槽函数
    void on_BtnStart_clicked();
    void on_BtnStop_clicked();
    void on_BtnRestart_clicked();
};
#endif // DIALOG_H