Closing program when widget is closed.

[metdos]

I have a program which instantiates and uses another class (subclass of Qwidget) . When I closed the widget, program does not terminate, how can I also terminate main function?

[yogeshgokul]

how can I also terminate main function?

You never need to terminate main function.

[metdos]

In main program, I have a infinite loop, and I need to stop infinite loop when widget is closed by user.

[wagmare]

I have a program which instantiates and uses another class (subclass of Qwidget) . When I closed the widget, program does not terminate, how can I also terminate main function?

means u want to terminate the whole application ...
use qApp->quit();

[metdos]

But, how will understand that widget is closed? I put qApp->quit(); to destructor of QT class, but it didn't work.

[spirit]

usually this line

...
QObject::connect( qApp, SIGNAL(lastWindowClosed()), qApp, SLOT(quit()) );
...

...
QObject::connect( qApp, SIGNAL(lastWindowClosed()), qApp, SLOT(quit()) );
...

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is added in main.cpp or you can use QApplication::setQuitOnLastWindowClosed

[metdos]

Should I rewrite quit() slot?

[spirit]

why? take a look at QCoreApplication::quit, moreover, you can't do this since this method is not virtual.

[wagmare]

no just use the connect spirit suggest you ..

quit() is a static slot
void QCoreApplication::quit () [static slot]

[nish]

no need of rewrite.. its like u want to rewrite exit(0)

[metdos]

Then I guess I should try another thing, because it does not work, after widget is closed, my program keeps working.

[spirit]

so, provide a compilable example which reproduces the problem to us.

[metdos]

here main function and function which contains infinite loop

int main(int argc, char *argv[])
{
 
	//GUI part
	QApplication a(argc, argv);
	rovkonInterface w; //subclass of Qwidget
	w.show();
 
	QObject::connect( qApp, SIGNAL(lastWindowClosed()), qApp, SLOT(quit()) );
 
	userInterface=&w;
 
	// start the receive thread
	ReceiveThread();
 
	return a.exec();
 
}
 
void ReceiveThread()
{
 
	rovkonInterface *w=((rovkonInterface *)userInterface);
	QApplication *a=((QApplication *)qtApplication);
 
 
	while ( lMustQuit == 0 )
	{	
		a->processEvents();
 
	}
 
 
}

int main(int argc, char *argv[])
{

	//GUI part
	QApplication a(argc, argv);
	rovkonInterface w; //subclass of Qwidget
	w.show();

	QObject::connect( qApp, SIGNAL(lastWindowClosed()), qApp, SLOT(quit()) );

	userInterface=&w;

	// start the receive thread
	ReceiveThread();

	return a.exec();

}

void ReceiveThread()
{
	
	rovkonInterface *w=((rovkonInterface *)userInterface);
	QApplication *a=((QApplication *)qtApplication);


	while ( lMustQuit == 0 )
	{	
		a->processEvents();

	}
		

}

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[spirit]

if you use another thread then tyr to add one more connection in main.cpp

...
QObject::connect( qApp, SIGNAL(lastWindowClosed()), thread, SLOT(quit()) );
QObject::connect( qApp, SIGNAL(lastWindowClosed()), qApp, SLOT(quit()) );
...

...
QObject::connect( qApp, SIGNAL(lastWindowClosed()), thread, SLOT(quit()) );
QObject::connect( qApp, SIGNAL(lastWindowClosed()), qApp, SLOT(quit()) );
...

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[spirit]

btw, you can use qApp insted of this QApplication *a=((QApplication *)qtApplication);

[metdos]

Thanks for the "qApp" tip.

and sorry for the bad names I gave to functions. Actually there is no other thread, there is just a function with infinite loop and I added "a->processEvents();" in order to prevent freezing in widgets as you can see in code above.

Simply ReceiveThread() continues to run infinite loop when widget is closed, I need to stop this infinite loop.

Thanks anyway

[wagmare]

in rovkonInterface class
is it a QDialog or QWidget ..
if QDialog we can receive
void QDialog::rejected ()
with that rejected call we can quit our application like

QObject::connect( w, SIGNAL(rejected()), qApp, SLOT(quit()) );

QObject::connect( w, SIGNAL(rejected()), qApp, SLOT(quit()) );

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[metdos]

It is Qwidget.

rovkonInterface w; //subclass of Qwidget

rovkonInterface w; //subclass of Qwidget

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in rovkonInterface class
is it a QDialog or QWidget ..
if QDialog we can receive
void QDialog::rejected ()
with that rejected call we can quit our application like

QObject::connect( w, SIGNAL(rejected()), qApp, SLOT(quit()) );

QObject::connect( w, SIGNAL(rejected()), qApp, SLOT(quit()) );

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[wagmare]

so u try emit your custom signal on rovkonInterface closeEvent()

reimplement closeEvent() in rovkonInterface() class
emit widgetClosed() // your custom signal
and

QObject::connect( w, SIGNAL(widgetClosed()), qApp, SLOT(quit()) );

[spirit]

so u try emit your custom signal on rovkonInterface closeEvent()

reimplement closeEvent() in rovkonInterface() class
emit widgetClosed() // your custom signal
and

QObject::connect( w, SIGNAL(widgetClosed()), qApp, SLOT(quit()) );

in that case you don't need to emit a signal, just call qApp->quit(); in closeEvent.