Adding automatic DPI scaling

[mrkrook2012]

I have noticed this bug before, it seems to occur on arch linux with KDE Plasma.
I loaded the same video into VLC and it does not have this bug.
I have seen this bug on 2 different laptops, both running Arch with KDE, the laptops have different screen sizes.

STEPS TO REPRODUCE:

1. Download Arch Linux with KDE Plasma
2. Use memento to view .mkv file or .mov (I have provided a snippet that causes the bug for me below)

Going into the settings and manually overriding the DPI Scaling fixes this bug.
Could something be added that automatically detects the scaling and applies the correct scaling?

snippet.mov

[ripose-jp]

Wayland stores DPI scaling as an integer, so there is no easy way to figure out what the fractional DPI scaling factor of the screen is. X11 doesn't have this problem, so you can run Memento using XWayland and I believe it won't be an issue. If someone can figure out how to calculate fractional DPIs under Wayland, I'll implement that and remove the manual override. I haven't been able to find any answers how so far though.

[stalkerg]

@ripose-jp it's already not an integer, last 2 years (before in staging and now it's a stable). Wayland is support float DPI.

[ripose-jp]

If that's true, I shouldn't need to make any code changes for DPI scaling to work automatically once Qt starts reporting the correct value.