头文件:

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QTime>
#include <QTimerEvent>
#include <QTimer>
#include <QtTextToSpeech>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

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

public slots:
    void timeout_slot();

private slots:
    void on_pushButton_clicked();

private:
    Ui::Widget *ui;

    int id;   //定时器的id

    QTimer *timer;

    //实例化一个语音播报者
    QTextToSpeech *speecher;
};
#endif // WIDGET_H

源文件:

#include "widget.h"
#include "ui_widget.h"

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
    , timer(new QTimer)
{
    ui->setupUi(this);

    //连接timeout 和自定的槽函数
    connect(timer, &QTimer::timeout, this, &Widget::timeout_slot);
    timer->start(1000);
}

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



void Widget::timeout_slot()
{
    //获取系统时间Qtime
    QTime sys_time = QTime::currentTime(); //获取到当前系统时间

    //将系统时间转换成字符串
    QString s = sys_time.toString("hh:mm:ss");

    //将系统时间设置到ui界面上的lab中
    ui->sysTime->setText(s);

    //居中
    ui->sysTime->setAlignment(Qt::AlignCenter);



}


void Widget::on_pushButton_clicked()
{
    QString alarm = ui->timeEdit->text();
    if(alarm <= ui->sysTime->text())
    {
        while(1)
        {
            speecher->say(ui->label_3->text());
        }
    }
}

思维导图: