QT 界面几秒后消失并跳转到另一个界面

需求

登录界面（login）点击登录（login）按钮后，跳转到等待界面（loginloading），然后3s后关闭等待界面并切换到主界面(mainwindow)。

核心代码

login.h

#include <QWidget>
#include "loginloading.h"
#include <QTimer>
public:
    Login(QWidget *parent = nullptr);
    ~Login();

    void Qtimer();
    
...........省略

private slots:
    void on_login_clicked();
signals:
    void show_loginloading();

    void show_mainwindow();

    void close_loginloading();
private:
    Ui::Login *ui;

    QTimer *m_timer;
};
#endif // Login_H

login.cpp

void Login::on_login_clicked()//登录按钮槽函数
{
    if(ui->lineEdit->text().trimmed() == tr("admin") && ui->lineEdit_2->text() == tr("admin"))//账号密码
        {
            this->hide();
            emit show_loginloading();
            m_timer = new QTimer(this);
            m_timer->setSingleShot(true);
            this->Qtimer();
            connect(m_timer, &QTimer::timeout, this, [=](){emit show_mainwindow();});
            connect(m_timer, &QTimer::timeout, this, [=](){emit close_loginloading();});
        }
        
..........省略

}
void Login::Qtimer()
{
    m_timer->start(3000);
}

loginloading.h

private slots:
    void receive_login_login();

    void receive_close_loginloading();

loginloading.cpp

void LoginLoading::receive_login_login()
{
    this->show();
}

void LoginLoading::receive_close_loginloading()
{
    this->close();
}

mainwindow.h

private slots:
	void receive_login_mainwindow();

mainwindow.cpp

void MainWindow::receive_login_mainwindow()
{
    this->show();
}

main.cpp

..........省略
   
    Login l;
    MainWindow w;
    LoginLoading ll;
    l.show();
    QObject::connect(&l,SIGNAL(show_loginloading()),&ll,SLOT(receive_login_login()));
    QObject::connect(&l,SIGNAL(show_mainwindow()),&w,SLOT(receive_login_mainwindow()));
    QObject::connect(&l,SIGNAL(close_loginloading()),&ll,SLOT(receive_close_loginloading()));
    return a.exec();
}

参考

https://blog.csdn.net/xiezhongyuan07/article/details/79885546