How to export QGraphicsScene to QImage with HiDPI

[dporobic]

I have following function that exports my QGraphicsScene to a QImage:

QImage MyGraphicsScene::image()
{
	auto scaleFactor = mDevicePixelRatioScaler->scaleFactor(); // Get the current scale factor in the example it was 2 for 200% scaling
	QImage image(sceneRect().size().toSize() * scaleFactor, QImage::Format_ARGB32_Premultiplied);
	image.fill(Qt::white);

	QPainter painter(&image);
	painter.setRenderHint(QPainter::Antialiasing);
	render(&painter);
        image.setDevicePixelRatio(scaleFactor);

	return image;
}

It works fine without HiDPI but with HiDPI enabled, like here set to 200% the exported image looses quality and it looks like this:

The original image looks like this:

Without the scale factor multiplying there the exported images would be small and look like there was no scaling at all so in order to get the size right I have to upscale it but as you can see, I lose quality.

Does anyone know how to do it right?

[dporobic]

Ok, it looks like the fix was as simple as setting this before creating the QApplication

QApplication::setAttribute(Qt::AA_EnableHighDpiScaling);