qt - QMainWindow close() 信号未发出

Question

为了在关闭从 QMainWindow 继承的窗口之前发出警告，我重新实现了它的 closeEvent，当我手动发出 close() 时，它可以正常工作。但是，单击“x”按钮不会触发此操作；它就退出了。

它确实为应用程序发出aboutToQuit()，我可以使用它在窗口关闭后“恢复”窗口。但我希望在最初关闭之前发出警告。

不知道问题出在哪里。该窗口是顶层窗口，没有正在运行的线程。我是否误解了实际连接到按钮单击的信号......？它是 close()，对吗？

Answer 1

在主窗口类 header 中( closeEvent 必须是虚拟的):

public:
    /*!
     * \brief closeEvent
     * \param event
     */
    virtual void closeEvent ( QCloseEvent * event );

然后在cpp中

void MainWindow::closeEvent( QCloseEvent *event )
{
    //! Ignore the event by default.. otherwise the window will be closed always.
    event->ignore();

    if(!EntitiesSaverObserver::Instance()->isAllSaved())
    {
        QMessageBox msgBox;
        msgBox.setWindowIcon(QIcon(":/Resources/Icons/warning.png"));
        msgBox.setIconPixmap(QPixmap(":/Resources/Icons/warning.png"));
        QString strToShow = QString("Some Entities has been created or modified...");
        msgBox.setText(strToShow);
        msgBox.setInformativeText("Do you want to save your changes?");
        msgBox.setStandardButtons(QMessageBox::Save | QMessageBox::Discard | QMessageBox::Cancel);
        msgBox.setDefaultButton(QMessageBox::Save);
        int ret = msgBox.exec();

        switch (ret) {
          case QMessageBox::Save:
            {
              // Save was clicked
              qDebug() << "SAVE";
              //! Do your stuff here
              // ....
              event->accept();
              break;
            }
          case QMessageBox::Discard:
            {
                // Don't Save was clicked
                qDebug() << "DISCARD";
                event->accept();
                break;
            }
          case QMessageBox::Cancel:
            {
              // Cancel was clicked
              qDebug() << "CANCEL";
              break;
            }
          default:
              // should never be reached
              break;
        }
    } else {
        event->accept(); // Do not need to save nothing... accept the event and close the app
    }
}

此外，如果您想在工具栏中放置一个按钮作为 QAction，您可以连接信号，然后:

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

这将调用主窗口的关闭事件。我希望这对您有帮助。