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A comment on Tell HN: Gnome on Wayland Is Amazing. Parent comment

Re:Tell HN: Gnome on Wayland Is Amazing by wing-_-nuts on Monday March 21, 2022 @11:30AM (#30755209)
Funny you should mention fractional scaling. I use gnome on wayland and enabling fractional scaling has a warning that it's really not recommended. Part of me wonders if this was simply a carry over from gnome on xorg, but I've mostly just made text larger and use a zoom extension in the browser.
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Re:Tell HN: Gnome on Wayland Is Amazing by marwis on Monday March 21, 2022 @12:02PM (#30755636)
Unless something changed Wayland does not support native fractional scaling and instead renders at nearest higher integer scale then does bitmap scaling down giving blurry output (compared to native fractional scaling as in Windows).
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Re:Tell HN: Gnome on Wayland Is Amazing by vetinari on Monday March 21, 2022 @01:46PM (#30757334)
When scaling down, you don't have blurry output. You won't get pixel-perfect, but you get sharp enough. MacOS does the same for fractional scale.

You get blurry when scaling UP. Xwayland does scale up, from 96 dpi to whatever fractional scale is set, so that's the reason why X apps are blurry. Native wayland app are not.

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Re:Tell HN: Gnome on Wayland Is Amazing by fsh on Monday March 21, 2022 @12:36PM (#30756176)
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.
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Re:Tell HN: Gnome on Wayland Is Amazing by marwis on Monday March 21, 2022 @01:09PM (#30756719)
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?

[0] https://gitlab.freedesktop.org/wayland/wayland-protocols/-/i...

Update:

I can still see open bugs such as https://gitlab.gnome.org/GNOME/mutter/-/issues/1135. Are they outdated?

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Re:Tell HN: Gnome on Wayland Is Amazing by fsh on Monday March 21, 2022 @03:54PM (#30758914)
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.

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Re:Tell HN: Gnome on Wayland Is Amazing by marwis on Monday March 21, 2022 @09:44PM (#30761934)
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.

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Re:Tell HN: Gnome on Wayland Is Amazing by fsh on Tuesday March 22, 2022 @04:24AM (#30763810)
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).

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Re:Tell HN: Gnome on Wayland Is Amazing by mijoharas on Monday March 21, 2022 @01:49PM (#30757372)
Sorry, maybe I wasn't clear.

When I was using X11 I had things set to fractional scaling because there wasn't good support for multiple monitors with different resolutions (and had it set to 1.5, where one monitor should be 2, and another should be 1, so I split the difference.)

Now on wayland, I have things set correctly, where scaling is set to 2 on a single monitor, and is set to 1 on the other monitor (and the application respects this and can be moved between monitors with the expected behaviour).

I also remember something about fractional scaling not being recommended on wayland (I believe it increases the amount of processing needed to be done by a lot.)

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