Printing QGraphicsScene Font Size Issue

[blumf]

Very simple example. I've made a QGraphicsObject based class with the painter event as:

void MyGfxObj::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
	QRectF rect(10.0,10.0, 100.0,100.0);

	QFont font("Arial");
	font.setPointSizeF(12.0);
	painter->setFont(font);

	painter->drawText(rect, "Test");
	painter->drawRect(rect);
}

And that renders fine on-screen. But when I try to render the graphics scene to a printer

void MainWindow::print()
{
	QPrinter printer(QPrinter::HighResolution);
	printer.setPageSize(QPrinter::A4);

	QPrintDialog *dialog = new QPrintDialog(&printer, this);
	if (dialog->exec() == QDialog::Accepted) {
		QPainter painter(&printer);
		scene.render(&painter);
	}
}

The text appears completely the wrong size (much bigger).
Why isn't the text being scaled to the device correctly?

[Ni.Sumi]

@blumf

Check QFontMetrics and this

[blumf]

@Ni.Sumi I know how to get the metrics of the font, what I don't understand is why a 12pt font is rendered at over 72pt when printing

To be explicit; why does .setPointSizeF(12.0) not result in a 12pt font when printing?

[Ni.Sumi]

This post is deleted!

[patrickkidd]

I am also having this problem with Qt-5.8.

[Asperamanca]

Easiest explanation would be a wrong dpi resolution. Dump printer.resolution() and check whether it makes sense for the printer you have. You can also try to change the DPI setting using printer.setResolution(dpi)