mainui.h(第二个界面)

#ifndef MAINUI_H
#define MAINUI_H

#include <QWidget>

namespace Ui {
class MainUi;
}

class MainUi : public QWidget
{
    Q_OBJECT

public:
    explicit MainUi(QWidget *parent = nullptr);
    ~MainUi();

public slots:
    void main_ui();

private:
    Ui::MainUi *ui;
};

#endif // MAINUI_H

mywidget.h(第一个界面)

#ifndef MYWIDGET_H
#define MYWIDGET_H

#include <QMainWindow>
#include<QDebug>
#include<QIcon>
#include<QPushButton>
#include<QLineEdit>
#include<QLabel>
#include<cstring>
#include<iostream>

class MyWidget : public QMainWindow
{
    Q_OBJECT

public:
    MyWidget(QWidget *parent = 0);
    ~MyWidget();
public slots:
    void log_slot();
    void close_slot();

signals:
    void log_sig();

private:
    QPushButton *btn1;
    QPushButton *btn2;
    QLineEdit *edt1;
    QLineEdit *edt2;
};

#endif // MYWIDGET_H

main.cpp

#include "mywidget.h"
#include <QApplication>
#include "mainui.h"
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MyWidget w;
    w.show();
    MainUi s;
    QObject::connect(&w,&MyWidget::log_sig,&s,&MainUi::main_ui);

    return a.exec();
}

mainui.cpp(第二个界面)

#include "mainui.h"
#include "ui_mainui.h"

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

}

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

void MainUi::main_ui(){
    this->show();
}

#include "mywidget.h"
#include <QMessageBox>

MyWidget::MyWidget(QWidget *parent)
    : QMainWindow(parent)
{
    //设置界面固定大小
    this->resize(1728,972);
    this->setFixedSize(1728,972);
    this->setWindowIcon(QIcon(":/pic/qq1.png"));
    this->setWindowTitle("WeGame");
    this->setWindowFlag(Qt::FramelessWindowHint);

    //设定主界面背景
    QLabel *lab1=new QLabel(this);
    lab1->resize(1728,972);
    lab1->setPixmap(QPixmap(":/pic/hb.jpg"));
    lab1->setScaledContents(true);

    //设置游戏图标
    QLabel *lab2=new QLabel(this);
    lab2->resize(400,300);
    lab2->move(664,130);
    lab2->setPixmap(QPixmap(":/pic/1.2.png"));
    lab2->setScaledContents(true);

    //设置qq图标
    QLabel *lab3=new QLabel(this);
    lab3->resize(70,70);
    lab3->move(800,450);
    lab3->setPixmap(QPixmap(":/pic/qq.png"));
    lab3->setScaledContents(true);

    //设置微信图标
    QLabel *lab4=new QLabel(this);
    lab4->resize(70,70);
    lab4->move(928,450);
    lab4->setPixmap(QPixmap(":/pic/wx.png"));
    lab4->setScaledContents(true);

    //账号编辑
    edt1=new QLineEdit(this);
    edt1->resize(390,65);
    edt1->move(710,524);
    edt1->setPlaceholderText("请输入账号:");

    //密码设置
    edt2=new QLineEdit(this);
    edt2->resize(390,65);
    edt2->move(710,610);
    edt2->setPlaceholderText("请输入密码:");
    edt2->setEchoMode(QLineEdit::Password);

    //复选框保存密码
    QLabel *edit3=new QLabel("保存密码",this);
    edit3->move(710,690);
    edit3->resize(140,40);

    //复选框自动登录
    QLabel *edit4=new QLabel("自动登录",this);
    edit4->move(870,690);
    edit4->resize(140,40);

    //二维码
    QLabel *edt3=new QLabel(this);
    edt3->setPixmap(QPixmap(":/pic/ew.png"));
    edt3->move(1030,690);
    edt3->resize(50,40);
    edt3->setScaledContents(true);

    //快速安全登录按钮
    btn1=new QPushButton("快速安全登录",this);
    btn1->resize(390,65);
    btn1->move(710,760);
    btn1->setStyleSheet("background-color:rgb(255,102,40)");

    //右上角的x
    btn2=new QPushButton("×",this);
    btn2->resize(40,40);
    btn2->move(1670,0);

    //右上角的-
    QPushButton *btn3=new QPushButton("-",this);
    btn3->resize(40,40);
    btn3->move(1630,0);

    //使用qt4将右上角x设置关闭触发
    connect(btn2,SIGNAL(clicked()),this,SLOT(close_slot()));

    //使用qt5将快速登录按钮设置触发事件
    connect(btn1,&QPushButton::clicked,this,&MyWidget::log_slot);
}

//上角按钮x(关闭)的槽函数
void MyWidget::close_slot()
{
    //静态函数版本
    int res=QMessageBox::question(this,
                                  "提示",
                                  "您是否确定要退出登录",
                                  QMessageBox::Yes | QMessageBox::No);
    if(res == QMessageBox::Yes){
        this->close();
    }else {

    }
}

//登录按钮的槽函数
void MyWidget::log_slot(){
    //比较账号和密码
    if(QString::compare("admin",edt1->text())==0 && QString::compare("123456",edt2->text())==0){
        //静态成员函数版
        int res=QMessageBox::information(this,
                                         "提示",
                                         "登陆成功",
                                         QMessageBox::Ok);
        //登陆成功触发信号
        emit this->log_sig();
        this->close();//关闭窗口
    }else {
        //成员属性版
        QMessageBox msg(QMessageBox::Critical,
                     "错误！",
                     "密码错误",
                     QMessageBox::Yes | QMessageBox::No,
                     this);
        int res =msg.exec();
        if(res==QMessageBox::Yes){
            edt2->clear();
        }else{
            this->close();
        }
    }
}

MyWidget::~MyWidget()
{

}