dual screen Qml, QWidget application

[Anas_Deshmukh]

hi everyone,

requirement is to run multi-display application using qt4.8.6 on ubuntu14.04.

on my primary display i am using qml,
on secondary diaplay i am running qwidget (by adjusting its x and y points).

i need help on two doubts i am having right now.

1. is my approach running secondary display is correct or not? can i evoke one more qml file from my main application. any more correct way to do same?

    QmlApplicationViewer viewer;
    viewer.setMainQmlFile(QLatin1String("qml/newDisplay/main.qml"));

2. currently when i pressed "Alt+F4" or "crash" happens, my main application and primary qml will close properly but secondary display keep running.

I figured out that "alt+f4" affect where i am having current focus. it surely close qml or qwidget only ONE at time.

kindly help me to write correct demo code. :)

/// secondaryDisplay.h /// 

#ifndef SECONDARYDISPLAY_H
#define SECONDARYDISPLAY_H
#include <QtCore>
#include <QDebug>
#include<QWidget>
#include <QLabel>
#include<QGraphicsScene>
#include <QGraphicsView>
#include <QGraphicsPixmapItem>

class secondaryDisplay: public QObject
{
    Q_OBJECT
public:
    secondaryDisplay();
//    QWidget * displayWidg//et = new QWidget();
    QLabel * tariffLabel;
    QString tariffStringAmount;
    QLabel *labelTariffAmount;// =  new QLabel(displayWidget);//("Total Tariff :", displayWidget);
    QString greetingMsg;

public :
    Q_INVOKABLE void showSecondaryDisplay();

public Q_SLOTS:

    Q_INVOKABLE void setDisplayTariffAmount(QString amount);
    Q_INVOKABLE void setGreetingMsg();

private:
};
#endif // SECONDARYDISPLAY_H

/// secondarydisplay.cpp //


#include "secondarydisplay.h"
secondaryDisplay::secondaryDisplay()
{
    this->tariffStringAmount="0";
}

void secondaryDisplay::setDisplayTariffAmount(QString amount)
{
    qDebug() << "secondaryDisplay :: slot called..";
    this->labelTariffAmount->setText(amount);
}

void secondaryDisplay::setGreetingMsg()
{
    this->greetingMsg="Welcome\nTo Secure Park.";
    qDebug() << "greetingMsg :  " << greetingMsg;
}

void secondaryDisplay::showSecondaryDisplay()
{
    QWidget *displayWidget = new QWidget();
    displayWidget->move(QPoint(1366, 0)); /// x cord. shift for second display
//    displayWidget->resize(400,250);
    displayWidget->setStyleSheet("background-color:white;");
    displayWidget->setWindowState(Qt::WindowFullScreen);


/// image label
    QLabel *imageLabel = new QLabel(displayWidget);
    imageLabel->setGeometry(10, 10, 1000, 150);

 // set a scaled pixmap to a w x h window keeping its aspect ratio

    QPixmap logo("/home/user/bundle/secure.jpg");

    int w = imageLabel->width();
    int h = imageLabel->height();
    imageLabel->setPixmap(logo.scaled(w,h));

///Greeting label
//    QLabel *greetinLabel = new QLabel(displayWidget);
//    greetinLabel->setText(this->greetingMsg);
//    greetinLabel->setGeometry(10, 10, 1000, 150);
//    greetinLabel->setStyleSheet("font: 40pt;");

///tariff label
    QLabel *labelTariffText =  new QLabel(displayWidget);//("Total Tariff :", displayWidget);
    labelTariffText->setText("TOTAL :");
//    label.setText("welcome");
    labelTariffText->setGeometry(10, 585, 400, 150);
    labelTariffText->setStyleSheet("font: 70pt;");
    labelTariffText->setAlignment(Qt::AlignLeft);

///tariff amount label
    labelTariffAmount =  new QLabel(displayWidget);//("Total Tariff :", displayWidget);
    labelTariffAmount->setText(this->tariffStringAmount);
//    label.setText("welcome");
    labelTariffAmount->setGeometry(380, 580, 600, 200);
//    labelTariffAmount->setStyleSheet("background-color:white;");
    labelTariffAmount->setStyleSheet("font: 80pt;");
    labelTariffAmount->setAlignment(Qt::AlignRight);

    displayWidget->show();
}

// main.cpp ///


#include <QApplication>
#include "qmlapplicationviewer.h"

#include "secondarydisplay.h"
#include <QSound>

#include <QtMultimedia>
#include <QAudio>

Q_DECL_EXPORT int main(int argc, char *argv[])
{
    QScopedPointer<QApplication> app(createApplication(argc, argv));

    QmlApplicationViewer viewer;
    viewer.addImportPath(QLatin1String("modules"));
    viewer.setOrientation(QmlApplicationViewer::ScreenOrientationAuto);
    viewer.setMainQmlFile(QLatin1String("qml/newDisplay/main.qml"));
    viewer.showExpanded();


    secondaryDisplay secondaryDisplayObj;
    secondaryDisplayObj.setGreetingMsg();
    secondaryDisplayObj.showSecondaryDisplay();

    return app->exec();
}

[karlheinzreichel]

@Anas_Deshmukh said in dual screen Qml, QWidget application:

currently when i pressed "Alt+F4" or "crash" happens, my main application and primary qml will close properly but secondary display keep running.

I think that is not possible, as you open your secondary display with widget->show().
So leaving the message loop in main application will close also your secondary display.

I assume your application will not be terminating after Alt+F4.

[J.Hilk]

@Anas_Deshmukh

You''ll have to get into your destructor functions, of the qml file and the QWidget, and call QApplication::quit manually.

//QML
Component.onDestruction: {
        Qt.quit()
    }

//QWidgets
MainWindow::~Mainwindow()
{
     delete ui;
     QApplication::quit();
}

[SGaist]

@J-Hilk It should happen automatically unless the quitOnLastWindowClosed property has been changed.

[J.Hilk]

@SGaist
Maybe I missread the question, but I thought the goal was it to close the whole application when either one one of the Windows (primary or secondary screen) is closed

currently when i pressed "Alt+F4" or "crash" happens, my main application and primary qml will close properly but secondary display keep running.

Target: alt+F4 -> close whole app

You're right however, that my post doesn't quite target the situation.
The Qt.Quit() should be in a Shortcut sequence and the widget should have an event filter listening for the alt+f4 key combo.

[Anas_Deshmukh]

Hi everyone,

i am sorry for late reply. At the moment i am using 'QApplication::destroyed()' signal to close my extra widget.
some how its working for me, but i am still doubtful in terms of standard coding.

thank you for your help. :)

// main.cpp

Q_DECL_EXPORT int main(int argc, char *argv[])
{
    QScopedPointer<QApplication> app(createApplication(argc, argv));
...
...
...
    secondaryDisplay secondaryDisplayObj ;//= new secondaryDisplay;
    viewer.rootContext()->setContextProperty("secondaryDisplayObj",&secondaryDisplayObj); /// qml acess
    secondaryDisplayObj.showSecondaryDisplay(); /// initiate my widget 
    QObject::connect(app.data(),SIGNAL(destroyed()), &secondaryDisplayObj, SLOT(deletSecondaryDisplay()));

// deletSecondaryDisplay :: my customised slot

}