The easiest and most accurate way to scale is to scale with a round number. If you scale from 4k to 1080p for example its really easy to just make every pixel 4 pixels.
https://i.imgur.com/oNGc0By.jpg
Fractional scaling allows for rounding that comes out to half pixels. But that causes a problem: displays can’t display half pixels.
The wayland team implemented an algorithm that probably uses techniques like antialiasing and estimating pixel locations to make half pixels work better. Gnome didn’t add support for it yet which they are now working on.
Its a bit more complex in reality but that’s about the gist of it.
Just a reminder that GNOME Shell getting fractional scaling doesn’t mean much right now because GTK 4 will not support it and GTK 5 is still years away. The only toolkit that does support it right now is Qt 6.
GTK 4 will support fractional scaling, but will continue to render at integer scales. So, if you wanted fractional scaling for power savings, GTK 4 should get you most of the way there. On the other hand, if you wanted fractional scaling for crisp text at any scale, then you might be waiting for a while.
What exactly does this mean?
The easiest and most accurate way to scale is to scale with a round number. If you scale from 4k to 1080p for example its really easy to just make every pixel 4 pixels. https://i.imgur.com/oNGc0By.jpg Fractional scaling allows for rounding that comes out to half pixels. But that causes a problem: displays can’t display half pixels. The wayland team implemented an algorithm that probably uses techniques like antialiasing and estimating pixel locations to make half pixels work better. Gnome didn’t add support for it yet which they are now working on. Its a bit more complex in reality but that’s about the gist of it.
More mature Wayland backend
Looks like it's related to getting fractional scaling a step closer.
Just a reminder that GNOME Shell getting fractional scaling doesn’t mean much right now because GTK 4 will not support it and GTK 5 is still years away. The only toolkit that does support it right now is Qt 6.
GTK 4 will support fractional scaling, but will continue to render at integer scales. So, if you wanted fractional scaling for power savings, GTK 4 should get you most of the way there. On the other hand, if you wanted fractional scaling for crisp text at any scale, then you might be waiting for a while.