This is incorrect. I use fractional scaling in Gnome Wayland for my 4K monitor. The native Wayland software (Firefox, all the Gnome stuff,...) scales perfectly. Only XWayland applications are somewhat blurry.
Interesting. I gave up on Gnome/Linux long time ago but was watching a relevant wayland bug [0] in the hopes it will be fixed one day but it seems to be still open. Maybe I've been watching a wrong bug?
It is not clear to me what exactly the relevance of the first bug is. Text in all Wayland programs is perfectly clear on my system with 150% fractional scaling.
I can reproduce some of the effects from the second bug when looking at my 4K monitor from an extremely small distance (a few cm). I am not sure if this is really a bug. It looks like antialiased edges that don't perfectly fit the pixel grid. Probably hard to avoid in any scaling scenario. In any case, it is not noticeable at a reasonable viewing distance.
If there is no way to tell Wayland application that it should scale by fraction then application can't render with such scale, no? This leads me to assumption that fractional scaling happens at compositor.
By native scaling I mean absolutely no bitmap scaling. If rendering happened at target scale then all pixels would match grid and no artifacts would be possible. I can't even imagine how ClearType could work with bitmap scaling when it targets individual subpixels.
I think people have wildly different sensitivity to resolution. I know some that can't tell difference between 4k and 1080p and 1080p scaled on 4k screen. Some crazy people even think MacOS has good font rendering.
No, the scaling is definitely done by the applications. I don't know how they do it, but it works.
I don't think it is possible to avoid having lines "in between" pixels when using fractional scaling. The physical pixel grid simply does not always align with the one at "100%" scale.
I specifically bought the 4K monitor to get crisp text rendering. Upscaling from 1080p (e.g. what XWayland does) is very noticeable to me. I don't see any difference between native Wayland fractional scaling, and setting Gnome to native resolution (except for the tiny UI elements).
