Qt 中将 QWidget 改为模态的方法

方法1：使用 setWindowModality()

// 设置为应用程序模态（阻止与所有窗口交互）
widget->setWindowModality(Qt::ApplicationModal);

// 设置为窗口模态（只阻止与父窗口交互）
widget->setWindowModality(Qt::WindowModal);

// 设置为非模态
widget->setWindowModality(Qt::NonModal);

// 示例
QWidget* modalWidget = new QWidget();
modalWidget->setWindowModality(Qt::ApplicationModal);
modalWidget->show();

方法2：使用 exec() 方法（像 QDialog 一样）

// 自定义 QWidget 子类，添加 exec() 方法
class ModalWidget : public QWidget {
    Q_OBJECT
public:
    ModalWidget(QWidget* parent = nullptr) : QWidget(parent) {
        setWindowFlags(Qt::Dialog);
        setWindowModality(Qt::ApplicationModal);
    }
    
    int exec() {
        show();
        m_eventLoop.exec();
        return m_result;
    }
    
public slots:
    void accept() {
        m_result = QDialog::Accepted;
        close();
    }
    
    void reject() {
        m_result = QDialog::Rejected;
        close();
    }
    
protected:
    void closeEvent(QCloseEvent* event) override {
        m_eventLoop.quit();
        QWidget::closeEvent(event);
    }
    
private:
    QEventLoop m_eventLoop;
    int m_result = QDialog::Rejected;
};

// 使用
ModalWidget* widget = new ModalWidget();
if (widget->exec() == QDialog::Accepted) {
    qDebug() << "用户接受了";
}

**方法3：使用setWindowModality+**QEventLoop

    FormVideoSnap *widget = new FormVideoSnap(nullptr);
    widget->setWindowModality(Qt::ApplicationModal);
    widget->setAttribute(Qt::WA_DeleteOnClose);

    QEventLoop loop;
    // 连接自定义aboutToClose 信号
    QObject::connect(widget, &FormVideoSnap::aboutToClose, [this](const QString& filePath) {
        m_lastSnapshotFilePath = filePath;
    });
    QObject::connect(widget, &FormVideoSnap::destroyed, &loop, &QEventLoop::quit);
    widget->show();
    loop.exec(); // 阻塞直到窗口关闭