Closing a Qt Quick application from QML

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Article Metadata

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Tested with

Devices(s): Nokia 900

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Compatibility

Platform(s): S60 5th Edition
Maemo

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Article

Keywords: QML, QDeclarativeView

Created: kratsan (17 Jun 2010)

Last edited: hamishwillee (11 Oct 2012)

Overview

This snippet shows how to trigger the closing of a Qt Quick application from QML code. This is needed especially in full screen applications, because there may not be any dedicated hardware key to close the application.

The following QML code calls the global Qt.quit() function which will trigger the ending of the application. In this example, we have used QDeclarativeView to show the Qt Quick UI and thus we must connect the QDeclarativeEngine::quit() signal to the QApplication::quit() slot.

NOTE: Had we used qmlviewer to interpret the QML, the Qt.quit() signal would have been automatically handled.

Preconditions

• Qt 4.7 or higher is installed on your platform.

Qt Project File

#To make sure we use declarative
QT += declarative
 
#To get files deployed on device / emulator
files.sources += ui.qml
DEPLOYMENT += files

Source

main.cpp

#include <QApplication>
#include <QDeclarativeView>
#include <QDeclarativeEngine>
 
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
 
    QDeclarativeView view;
    view.setSource(QUrl("./ui.qml"));
    view.setResizeMode(QDeclarativeView::SizeRootObjectToView);
 
    QObject::connect((QObject*)view.engine(), SIGNAL(quit()), &app, SLOT(quit()));
 
#if defined(Q_WS_S60) || defined(Q_WS_MAEMO)
    view.showMaximized();
#else
    view.setGeometry(100,100, 800, 480);
    view.show();
#endif
 
    return app.exec();
}

ui.qml

import Qt 4.7
 
Rectangle {
    anchors.fill: parent; color: "black"
 
    Rectangle {
        anchors.centerIn: parent
        width: 100; height: 40; radius: 5; color: "lightgray"
 
        Text { anchors.centerIn: parent; text: "Quit"; color: "black" }
 
        MouseArea {
            anchors.fill: parent
            onClicked: Qt.quit()
        }
    }
}

Postconditions

The calling of the Qt.quit() function in QML code caused the emission of the QDeclarativeEngine::quit() signal, and because this signal was connected to the QApplication::quit() slot, the application was closed.