QML: Asking confirmation before closing application - c++

Question

I have a QtQuick application. When the user tries to close the application, I want an "Are you sure?" window to pop up.
My main C++ class has this:
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QQmlApplicationEngine engine;
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
return app.exec();
}
And my main QML class has an application window:
ApplicationWindow {
id: root
...
}
Where and how would I catch the close event? I read about overriding closeEvent() from QMainWindow method or something, but I don't have a QMainWindow and I don't know where I'd put that code.
So I'd like to know how to prevent the app from closing and have something else happen instead, and how I'd close the app later when the user clicks "ok" in the confirmation dialog.
As far as I can see, the ApplicationWindow's "onClosing" only allows me to do some clean up before the inevitable close, but it doesn't prevent the close (please correct me if I'm wrong)

Answer 1

I solved it.
ApplicationWindow {
id: root
onClosing: close.accepted = false
}
This prevents the app from closing.
root.close()
This closes the app.

Answer 2

import QtQuick 2.13
import QtQuick.Layouts 1.12
import QtQuick.Controls 2.13
import QtQuick.Controls 1.4
import QtQuick.Dialogs 1.3
ApplicationWindow {
property bool closing: false
MessageDialog {
id: exitMessageDialogId
icon: StandardIcon.Question
text: "Are you sure to exit?"
standardButtons: StandardButton.Yes | StandardButton.No
onYes: {
closing = true
mainWindowId.close()
}
}
onClosing: {
close.accepted = closing
onTriggered: if(!closing) exitMessageDialogId.open()
}
id: mainWindowId
}
In this case it just close current window.

Answer 3

//use Qt 5.11.2
// for android y desktop
import QtQuick 2.9
import QtQuick.Controls 2.4
import QtQuick.Layouts 1.3
import QtQuick.Dialogs 1.2
ApplicationWindow {
title: qsTr("xxxx xxxx")
id: mainWindow
visible: true
//desision para salir
MessageDialog {
id: messageDialogQuit
title: "Deseas salir?"
icon: StandardIcon.Question
text: "xxxxxxxxxxxxxxxxxxxxxxxxx."
standardButtons: StandardButton.Yes |StandardButton.No
// Component.onCompleted: visible = true
onYes: Qt.quit()
// onNo: console.log("didn't copy")
}
onClosing:{
close.accepted = false
onTriggered: messageDialogQuit.open()
}
menuBar: MenuBar {
id: m_menu
LayoutMirroring.enabled: true
LayoutMirroring.childrenInherit: true
anchors.left: parent.left
Menu {
title: qsTr("File")
MenuItem {
text: qsTr("Exit")
onTriggered: messageDialogQuit.open()
}
}
}
width: 400
height: 300
}