Drawer::Drawer(QWidget *parent, Qt::WindowFlags f) :QToolBox(parent, f) { setWindowTitle(tr("Myself QQ 2013")); //设置主窗口的标题 setWindowIcon(QPixmap(":/image/qq.png")); //设置主窗体标题栏图标 toolBtn1 = new QToolButton; toolBtn1->setText(tr("道枝小尧")); toolBtn1->setIcon(QPixmap(":/image/spqy.png")); toolBtn1->setIconSize(QPixmap(":/image/spqy.png").size()); toolBtn1->setAutoRaise(true); toolBtn1->setToolButtonStyle(Qt::ToolButtonTextBesideIcon); connect(toolBtn1, SIGNAL(clicked()), this, SLOT(showChatWidget1())); toolBtn2 = new QToolButton; toolBtn2->setText(tr("忆梦如澜")); toolBtn2->setIcon(QPixmap(":/image/ymrl.png")); toolBtn2->setIconSize(QPixmap(":/image/ymrl.png").size()); toolBtn2->setAutoRaise(true); toolBtn2->setToolButtonStyle(Qt::ToolButtonTextBesideIcon); connect(toolBtn2, SIGNAL(clicked()), this, SLOT(showChatWidget2()));在此基础上添加登录界面

在这段代码中，Drawer 类的构造函数已经实现了 QQ 聊天界面的主体部分，现在需要添加登录界面。可以在构造函数中添加一个 QDialog 对象，该对象包含用户名和密码的输入框以及登录和取消按钮。当用户点击登录按钮时，检查输入的用户名和密码是否正确，如果正确则关闭登录界面并显示 QQ 聊天窗口，否则弹出错误提示框。

以下是可能的实现方式：

Drawer::Drawer(QWidget *parent, Qt::WindowFlags f)
    : QToolBox(parent, f)
{
    setWindowTitle(tr("Myself QQ 2013"));
    setWindowIcon(QPixmap(":/image/qq.png"));

    // 添加登录界面
    QDialog loginDialog(this);
    loginDialog.setWindowTitle(tr("登录"));
    QLabel* nameLabel = new QLabel(tr("用户名："));
    QLineEdit* nameEdit = new QLineEdit;
    QLabel* pwdLabel = new QLabel(tr("密码："));
    QLineEdit* pwdEdit = new QLineEdit;
    pwdEdit->setEchoMode(QLineEdit::Password);
    QPushButton* loginButton = new QPushButton(tr("登录"));
    QPushButton* cancelButton = new QPushButton(tr("取消"));
    QHBoxLayout* nameLayout = new QHBoxLayout;
    nameLayout->addWidget(nameLabel);
    nameLayout->addWidget(nameEdit);
    QHBoxLayout* pwdLayout = new QHBoxLayout;
    pwdLayout->addWidget(pwdLabel);
    pwdLayout->addWidget(pwdEdit);
    QVBoxLayout* buttonLayout = new QVBoxLayout;
    buttonLayout->addWidget(loginButton);
    buttonLayout->addWidget(cancelButton);
    QVBoxLayout* mainLayout = new QVBoxLayout(&loginDialog);
    mainLayout->addLayout(nameLayout);
    mainLayout->addLayout(pwdLayout);
    mainLayout->addLayout(buttonLayout);
    connect(loginButton, &QPushButton::clicked, [&](){
        QString username = nameEdit->text();
        QString password = pwdEdit->text();
        if (username == "admin" && password == "123456") {
            loginDialog.close();
            showChatWidget1();
        } else {
            QMessageBox::warning(this, tr("错误"), tr("用户名或密码不正确！"));
        }
    });
    connect(cancelButton, &QPushButton::clicked, [&](){
        loginDialog.close();
        close();
    });

    // 添加聊天窗口按钮
    toolBtn1 = new QToolButton;
    toolBtn1->setText(tr("道枝小尧"));
    toolBtn1->setIcon(QPixmap(":/image/spqy.png"));
    toolBtn1->setIconSize(QPixmap(":/image/spqy.png").size());
    toolBtn1->setAutoRaise(true);
    toolBtn1->setToolButtonStyle(Qt::ToolButtonTextBesideIcon);
    connect(toolBtn1, &QToolButton::clicked, this, &Drawer::showChatWidget1);

    toolBtn2 = new QToolButton;
    toolBtn2->setText(tr("忆梦如澜"));
    toolBtn2->setIcon(QPixmap(":/image/ymrl.png"));
    toolBtn2->setIconSize(QPixmap(":/image/ymrl.png").size());
    toolBtn2->setAutoRaise(true);
    toolBtn2->setToolButtonStyle(Qt::ToolButtonTextBesideIcon);
    connect(toolBtn2, &QToolButton::clicked, this, &Drawer::showChatWidget2);
}

注意，这里使用了 C++11 中的 lambda 表达式来简化信号槽的连接，同时也使用了新的信号槽语法。