How To Detect if the User Closed the window?

[Yousef Alaa Hussain]

I tried searching YouTube to find how to detect if the user clicked on the x button to close the window, but didn't manage to find, does anyone know how to do it in qt c++

[Christian Ehrlicher]

See https://doc.qt.io/qt-6/qwidget.html#closeEvent

[Yousef Alaa Hussain]

@Christian-Ehrlicher I am a beginner and I didn't understand that much what is written in the doc

[Christian Ehrlicher]

Override this function and do whatever you want to do in there.

[JonB]

@Yousef-Alaa-Hussain
Qt does not issue a signal on closing a window/widget. However it does call a closeEvent() method in any widget. If you want to capture/act on that you should subclass whichever QWidget-derived the "window" is so that you can override that (virtual protected) method.

If you really don't want to subclass you could alternatively install an event filter and look for the QEvent::close event.

Both of these are illustrated in e.g. https://stackoverflow.com/questions/17480984/how-do-i-handle-the-event-of-the-user-pressing-the-x-close-button. It also shows using aboutToQuit() if all you really want to know is when the whole application is being closed.

[Yousef Alaa Hussain]

@JonB thank you so much for your answer
and i am really sorry for asking a lot of questions but,
as you can see here i have a function here that has a simple label and text input field and two buttons save and cancel

void MainWindow::WriteAnyButtonClicked()
{
    QWidget* WriteAnyWindow = new QWidget();

    QVBoxLayout* MainLayout = new QVBoxLayout();

    // Top Layout
    QHBoxLayout* TopLayout = new QHBoxLayout();

    QLabel* EnterAnyLabel = new QLabel("Enter What You Want To Share: ");
    EnterAnyLabel->setAlignment(Qt::AlignLeft);
    EnterAnyLabel->setAlignment(Qt::AlignVCenter);

    TopLayout->addWidget(EnterAnyLabel);


    //Middle Layout
    QHBoxLayout* MiddleLayout = new QHBoxLayout();

    QTextEdit* EnterAnyTextEdit = new QTextEdit();
    EnterAnyTextEdit->setFocus();

    MiddleLayout->addWidget(EnterAnyTextEdit);

    // Bottom Layout
    QHBoxLayout* BottomLayout = new QHBoxLayout();

    QPushButton* Save_Button = new QPushButton("Save");
    Save_Button->setFixedSize(100, 50);

    QPushButton* Exit_Button = new QPushButton("Cancel 🇽");
    Exit_Button->setFixedSize(50, 50);


    BottomLayout->addWidget(Save_Button);
    BottomLayout->addWidget(Exit_Button);


    MainLayout ->addLayout(TopLayout);
    MainLayout ->addLayout(MiddleLayout);
    MainLayout ->addLayout(BottomLayout);

    WriteAnyWindow->setLayout(MainLayout);
    WriteAnyWindow->setWindowTitle("Send By Text");
    WriteAnyWindow->setFixedSize(400,400);
    WriteAnyWindow->show();


    // Button Connects
    connect(Exit_Button,&QPushButton::clicked, this,[&](){delete WriteAnyWindow;});
}

and i want to check when this widget is closed to automatically save the input that the user entered in the textinput,
do you know how to do this? do i really need to rearrange all of this code to an entire sperate class just to get this protected close event funtion and then create a funtion for it like this:

void MainWindow::closeEvent (QCloseEvent *event)
{
    QMessageBox::StandardButton resBtn = QMessageBox::question( this, "The Sender",
                                                               tr("Are you sure?\n"),
                                                               QMessageBox::Cancel | QMessageBox::No | QMessageBox::Yes,
                                                               ,QMessageBox::Cancel);
    if (resBtn != QMessageBox::Yes) {
        event->ignore();
    } else {
        event->accept();
    }
}

really?
and thanks!

[JonB]

@Yousef-Alaa-Hussain
As I wrote there are two possibilities.

• Subclass and override closeEvent(). Your code looks reasonable.

• If you do not want to "rearrange all of this code to an entire sperate class" (I don't see the problem, you seem to have already done it) then you can do it by installing an event filter.

I already wrote just this and referred you to a link showing both alternatives. I am not sure what you are actually asking now.

[Yousef Alaa Hussain]

@JonB

@JonB said in How To Detect if the User Closed the window?:

I don't see the problem, you seem to have already done it

actually, this close event is for the entire window (the main window) but
if the user clicks a button inside this main window, another window will pop up, and I wanted to detect when the user closes the new window that popped up after the button got clicked,

I guess I need to make an entire new class, uh, qt is very hard as a beginner, I hope I get out of the hell of beginner

So now I will try installing that I don't know thing you talked about, and I will see if I can adapt with it. If there is a tutorial out there for this thing I need to install, let's hope.

Thank you so much, and sorry for wasting your time

[JonB]

@Yousef-Alaa-Hussain

another window will pop up, and I wanted to detect when the user closes the new window that popped up

if the "window which pops up" is a (modal) dialog then you are told when it is closed. If not a modal dialog then you will have to subclass the window/widget or use an event filter.

[Pl45m4]

@Yousef-Alaa-Hussain said in How To Detect if the User Closed the window?:

void MainWindow::WriteAnyButtonClicked()

This function creates new widgets and layouts every time it's called (on button click, it seems).
You know that, right?!
It also leaks memory since you are not using the features of the QObject-tree nor deleting the pointers afterwards.
(Edit: you delete WriteAnyWindow forcefully, which is not recommended.)

However, the closeEvent looks good, as @JonB already mentioned.

[SGaist]

Hi,

If I have understood things correctly, wouldn't QInputDialog::getText do what you want ?