How do I make my app appear on the secondary monitor?

Sprezzatura

I am able to successfully override the beginning size and position of the screen, but not which monitor it appears on. Using Visual Studio, Windows 10, Qt 5.13.

Here's what I have tried (note screen is set to '1', the secondary monitor)

In the following case, 'qwin' is NULL, can't invoke setScreen()

MainWindow::MainWindow()	// constructor of main window; 'MainWindow' is a QMainWindow which inherits from QWidget
{	// 'theApp' is QApplication *
	QWindow *qwin = windowHandle();
	if(qwin)	// 'qwin' is NULL, even though the parent is a QMainWindow which inherits from QWidget
	{	QList<QScreen *> qscreens = theApp->screens();
		if(screen < qscreens.size())
			qwin->setScreen(qscreens[screen]);
	}
}

In the following case, 'qwin' is NULL, can't invoke setScreen()

MainWindow::MainWindow()
{	QWidget *topWidg = window();
	if(topWidg)		// not NULL
	{	QWindow *qwin = topWidg->windowHandle();
		if(qwin)	// NULL
		{	QList<QScreen *> qscreens = theApp->screens();
			if(screen < qscreens.size())
				qwin->setScreen(qscreens[screen]);
		}
	}
}

In the following case, 'qwin' is NOT NULL, but setScreen() does not take effect,
the app stays on primary screen (0) instead of appearing on secondary screen (1)

MainWindow::MainWindow()
{	QDesktopWidget qdskWidg = theApp->desktop(); // 'theApp' is QApplication 
	if(qdskWidg)	// not NULL
	{	QWindow *qwin = qdskWidg->windowHandle();
		if(qwin)	// not NULL
		{	QList<QScreen *> qscreens = theApp->screens();
			if(screen < qscreens.size())
				qwin->setScreen(qscreens[screen]);	// stays on primary (0) even though 'screen' is 1
		}
	}
}

Does anyone have a simple "Hello World" example that explicitly positions itself on the second monitor?

Thanks.

SGaist

Hi,

From the top of my head, I would get the center of the screen geometry and apply that to the widget.

Sprezzatura

@SGaist You mean like this:

QDesktopWidget *desktopWidget = qApp->desktop();
QRect secondScreenGeometry = desktopWidget->screenGeometry(1);
myWidget->move(secondScreenGeometry.center());

Does not work.

hskoglund

Hi, try:

myWidget->setGeometry(secondScreenGeometry);