Black border issue (with HiDPi display) Summary

[ShuffleWire]

Hello Team, Hello @omichel

There are a lot of user opening issues regarding Black border issue, mostly due to HiDPi display.
I don't know how to properly fix it, but I think it should be good to gather every tickets under this one, and Pin this one.
So we could consolidate the issue, and user won't have to open new issue each time.

Would you be ok pinning it ?

Do we want as well to close to issues ? (maybe as duplicate of this one ?)

Thanks

List of issues :

#6939
#6872
#6894
#6276 (this one might give the most infos)
#6894
#6531
#6498
#6411
#6055

With VR mode
#6900

not sure of this one
#6801

Please add others if you find others

[CoolSpy3]

One more:
#6979

[unmais]

A workaround that made the trick for me: turning off fractional scaling on Plasma.

[omichel]

One more:
#6989

[CoolSpy3]

This latest issue got me thinking. I did some tests, and so far, I've only been able to reproduce this under fractional scaling, so I bet that's important. I did some more digging, and it looks like WbWrenWindow::updateViewportDimensions() gets some scaling factor from Qt and truncates it to an int. Not 100% sure that that's the cause, but it seems pretty likely. The downside is that it looks like the reason for that is that a bunch of other code assumes that that value's an integer, so even if this does turn out to be the fix, it will likely involve some other changes and possibly will introduce some new bugs.

[CoolSpy3]

Alright, I just sent a notice to all the issues here that we have a possible fix in the latest nightly! (With the exception of #6801 and #6900 as I don't think those are related. The bug I fixed was an integer truncation error, so we'd expect to see incorrectly scaled rendering; not no rendering at all.)

Hopefully, we hear back from one or two of them in a few days and we can close all of these issues! (I don't think we'll get responses from everyone given that some of them are rather old.)