CODEWITHSUNDEEP
c++qtqt5qwidgetqtwidgets
Violet Giraffe
Violet Giraffe

Reputation: 33605

Is it possible to use WA_DeleteOnClose attribute with a main window that has no parent?

I'm experimenting with the WA_DeleteOnClose attribute, which implements exactly what I need. Much more neat than doing the same manually. There's a problem, however: if I construct my QMainWindow that WA_DeleteOnClose is applied to with no parent, it doesn't get deleted on close. And if I do set a parent (the main QMainWindow of the application), the secondary QMainWindow in question loses its taskbar button, which is unacceptabe. How can I solve this dilemma?

Upvotes: 1

Views: 1671

Answers (1)

Kuba hasn't forgotten Monica
Kuba hasn't forgotten Monica

Reputation: 98505

The WA_DeleteOnClose should work for any top-level widget. If it doesn't, it's a bug, or you're doing something else wrong, like perhaps running a nested event loop. A simple test for whether the window gets deleted would be:

QObject::connect(widget, &QObject::destroyed, [](QObject * obj){
  qDebug() << obj << "was destroyed";
});

WA_DeleteOnClose is applied to with no parent, it doesn't get deleted

There's no code in the implementation of WA_DeleteOnClose behavior that is affected by the widget having a parent. As long as the widget is-a Qt::Window, it will be deleted. See closeHelper.

the secondary QMainWindow in question loses its taskbar button, which is unacceptable

This probably applies to any QWidget, not only QMainWindow.

To confirm, does this test case not work for you? Let us know what the application output shows.

#include <QLabel>
#include <QPointer>
#include <QApplication>

int main(int argc, char ** argv) {
  QApplication app(argc, argv);
  QPointer<QLabel> label = new QLabel("Hello, world");
  label->setAttribute(Qt::WA_DeleteOnClose);
  label->setAttribute(Qt::WA_QuitOnClose);
  label->show();
  app.exec();
  qDebug() << qVersion() << label; // will be null if label was deleted
  return 0;
}

Upvotes: 1

Related Questions