How to avoid leaking memory?

spode

why do i am forced to use
@
QDeclarativeView *schermataParola = new QDeclarativeView;
@

to view a .qml file?
there is no way to close the unused windows?

vsorokin

Can you give more details, what do you mean?

Zlatomir

Doesn't your QDeclarativeView have a QWidget* parent? I mean the code posted is your actual code?
Don't you have something like:
@QDeclarativeView *schermataParola = new QDeclarativeView(someWidgetpointer);@
or put the schermataParola into a layout?

In case you do set a parent or it gets a parent (for example by putting schermataParola into a layout) the allocated memory will be deleted by the parent (when parent gets deleted or out of scope).

If it doesn't get a parent you can set the Qt::WA_DeleteOnClose attribute or manually delete the pointer when the widget work is done.

spode

@

void gestore::visualizzaParola(int index)
{
QDeclarativeView *schermataParola = new QDeclarativeView;
biglietto bigliettocorrente = (biglietto) this->makeListaParolaSalvate(this->getCurrentFilter()).at(index);
QDeclarativeContext *rootContext = schermataParola->rootContext();

rootContext->setContextProperty("sfondoBiglietto", bigliettocorrente->gettipo());
rootContext->setContextProperty("currentWort", bigliettocorrente->getwort());
rootContext->setContextProperty("currentBeispiel", bigliettocorrente->getbeispiel());
rootContext->setContextProperty("currentParola", bigliettocorrente->getparola());
rootContext->setContextProperty("currentEsempio", bigliettocorrente->getesempio());

schermataParola->setSource(QUrl::fromLocalFile&#40;"qml/HeilfeFuerVieleWoerterZuErinnern/schermataParola.qml"&#41;);
schermataParola->show();

}
@

you can see that it does not fall cause in that window there is nothing to close the window: there are just signals to open other windows with qt c++.

lgeyer

You will have to provide a possibility within your QML document to close it, usually a button or key event connected to Qt.quit(). Then the QDeclarativeEngine::quit() signal is emitted (accessible through QDeclarativeView::engine()), which has to be connected to a slot which handles the signal by for example deleting the view (QDeclarativeView::deleteLater()) or quitting the application.

See "Getting Started Programming with QML":http://doc.qt.nokia.com/latest/gettingstartedqml.html and "Closing a Qt Quick application from QML":http://www.developer.nokia.com/Community/Wiki/CS001626_-_Closing_a_Qt_Quick_application_from_QML.

spode

so, how do you use Qt::WA_deleteonclose attribute?
@
QDeclarativeView *view = new QDeclarativeView;
view->setAttribute(Qt::WA_DeleteOnClose);
view->rootContext()->setContextProperty("parolemodello", QVariant::fromValue(this->makeListaParolaSalvate(this->getCurrentFilter())));
view->setSource(QUrl::fromLocalFile("qml/HeilfeFuerVieleWoerterZuErinnern/main.qml"));
view->show();

QObject *obj = view->rootObject();
QObject::connect(obj, SIGNAL(signal_creaNuovaParola()), this, SLOT(creaNuovaParola()));
QObject::connect(obj, SIGNAL(signal_filterChanged(QString)), this, SLOT(visualizzaSchermataPrincipaleSlot(QString)));
QObject::connect(obj, SIGNAL(signal_visualizzaParola(int)), this, SLOT(visualizzaParola(int)));

@

so it does not function...

lgeyer

Of course it doesn't, because you have to have some piece of code in your QML which calls Qt.quit() and the quit() signal connected to some slot (preferably to close()) in C++. If you have the WA_DeleteOnClose flag set your view will get deleted too (as soon as the window is closed).

Have you taken a look at the "Closing a Qt Quick application from QML":http://www.developer.nokia.com/Community/Wiki/CS001626_-_Closing_a_Qt_Quick_application_from_QML link I've posted?

spode

yes, yes, i understand, but i need something that allows me to close a window as i open another. could please explain me how to realize that thing with QWigdet, please?

lgeyer

Just call view->close() when you open the other window.

spode

right, but "view" is for me a local variable...

lgeyer

Make view a member variable then. If the other widget belongs to the same class it will be accessible directly, otherwise you will have to make it globally accessible, by

exposing it through a getter of your class and
making this class globally accessible
@
class gestore
{
public:
gestore()
{
view = new QDeclarativeView;
...
qApp->setProperty("gestore", QVariant::fromValue<gestore*>(this));
}
QDeclarativeView getView() const { return view; }

private:
QDeclarativeView* view;
}
Q_DECLARE_METATYPE(gestore*);
...
qApp->property("gestore").value<gestore*>()->getView()->close();
@
Brain to terminal. Not tested. Exemplary.