第二章：QT核心机制（一）

作业

1> 手动将登录项目实现，不要使用拖拽编程

并且，当点击登录按钮时，后台会判断账号和密码是否相等，如果相等给出登录成功的提示，并且关闭当前界面，发射一个跳转信号，如果登录失败，则给出登录失败的提示，并清空密码框

当点击取消按钮时，直接关闭当前登录框

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QLineEdit>
#include <QLabel>
#include <QPushButton>
#include <QCheckBox>
#include <QPainter>
#include <QBitmap>
#include <QPainterPath>
#include <QDebug>
#include <QApplication>

class MainWindow : public QMainWindow
{
    Q_OBJECT

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


private slots:
    void onLoginButtonClicked();
    void onCancelButtonClicked();

private:
    void setupWindow();
    void setupWidgets();
    void setupPlaceholderText();
    bool validateLogin();
    QLineEdit *accountEdit;
    QLineEdit *passwordEdit;
    QLabel *accountLabel;
    QLabel *passwordLabel;
    QPushButton *loginButton;
    QPushButton *cancelButton;
    QCheckBox *rememberCheckBox;
    QCheckBox *autoLoginCheckBox;
    QLabel *avatarLabel;
};

#endif // MAINWINDOW_H

#include "mainwindow.h"

#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}

#include "mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    // 设置窗口固定尺寸
    setFixedSize(600, 800);
    // 设置窗口标题
    setWindowTitle("QQ");
    setWindowIcon(QIcon("E:/a-U盘备份/a资料/证件/头像.jpg"));
    //设置窗口样式表
    setWindowOpacity(0.9);
    setStyleSheet("background-color:rgb(74, 255, 219);");  //设置背景色

    // 头像标签
    avatarLabel = new QLabel(this);
    avatarLabel->setGeometry(230, 150, 151, 151);

    QPixmap originalPixmap("E:/a-U盘备份/a资料/证件/头像.jpg");
    if (!originalPixmap.isNull()) {
        QPixmap circularPixmap(avatarLabel->size());
        circularPixmap.fill(Qt::transparent);

        QPainter painter(&circularPixmap);
        painter.setRenderHint(QPainter::Antialiasing);
        painter.setPen(Qt::NoPen);
        painter.drawRoundedRect(0, 0, circularPixmap.width(), circularPixmap.height(),
                                circularPixmap.width() / 2, circularPixmap.width() / 2);
        QPainterPath path;
        path.addRoundedRect(0, 0, circularPixmap.width(), circularPixmap.height(), circularPixmap.width() / 2, circularPixmap.width() / 2);
        painter.setClipPath(path);
        painter.drawPixmap(0, 0, originalPixmap.scaled(circularPixmap.size(), Qt::KeepAspectRatioByExpanding, Qt::SmoothTransformation));

        avatarLabel->setPixmap(circularPixmap);
    }

    // 账号标签
    accountLabel = new QLabel("账号:", this);
    accountLabel->setGeometry(60, 480, 81, 50);
    // 账号输入框
    accountEdit = new QLineEdit(this);
    accountEdit->setGeometry(160, 480, 400, 50);
    accountEdit->setAlignment(Qt::AlignCenter);
    accountEdit->setPlaceholderText("请输入账号");

    // 密码标签
    passwordLabel = new QLabel("密码:", this);
    passwordLabel->setGeometry(60, 550, 81, 50);
    // 密码输入框
    passwordEdit = new QLineEdit(this);
    passwordEdit->setGeometry(160, 550, 400, 50);
    passwordEdit->setEchoMode(QLineEdit::Password);
    passwordEdit->setAlignment(Qt::AlignCenter);
    passwordEdit->setPlaceholderText("请输入密码");

    // 登录按钮
    loginButton = new QPushButton("登录", this);
    loginButton->setGeometry(130, 660, 150, 50);

    // 取消按钮
    cancelButton = new QPushButton("取消", this);
    cancelButton->setGeometry(330, 660, 150, 50);

    // 记住密码复选框
    rememberCheckBox = new QCheckBox("记住密码", this);
    rememberCheckBox->setGeometry(120, 620, 200, 30);

    // 自动登录复选框
    autoLoginCheckBox = new QCheckBox("自动登录", this);
    autoLoginCheckBox->setGeometry(330, 620, 200, 30);

    // 连接按钮点击信号到对应的槽函数
    bool connectResult1 = connect(loginButton, &QPushButton::clicked, this, &MainWindow::onLoginButtonClicked);
    bool connectResult2 = connect(cancelButton, &QPushButton::clicked, this, &MainWindow::onCancelButtonClicked);
    if (!connectResult1 ||!connectResult2) {
        qDebug() << "信号 - 槽连接失败";
    }
}

MainWindow::~MainWindow()
{
}

bool MainWindow::validateLogin()
{
    QString account = accountEdit->text();
    QString password = passwordEdit->text();
    // 这里是简单的校验逻辑，可根据实际需求修改
    return account == "123456" && password == "654321";
}

void MainWindow::onLoginButtonClicked()
{
    if (validateLogin()) {
        qDebug() << "登录成功";
        qApp->quit();
    } else {
        qDebug() << "登录失败";
        passwordEdit->clear();
    }
}

void MainWindow::onCancelButtonClicked()
{
    close();
}

2> 思维导图