How to detect a HiDPI display?

[Vadi2]

I'm not clear on how to detect if a display is HiDPI with Qt. I've tried QApplication.desktop()->screen()->devicePixelRatio() but even that returns 1 for a display that is 3840x2160.

Has anyone got hints on how to do this successfully?

[beecksche]

@Vadi2
I have no experience with HiDPI, but maybe you find some information here.

Maybe these functions helps: https://doc.qt.io/qt-5/qpaintdevice.html#physicalDpiX and https://doc.qt.io/qt-5/qpaintdevice.html#physicalDpiY