Gnome 3.16 HiDPI scaling only accepts integers

Question

I recently upgraded to Ubuntu 15.04 with Gnome 3.16, which is working really great on my machine (despite what I found on many forums around the web). Having a high DPI screen however (13.3" with 1920x1080) I need to scale the entire system to use it. There is a setting for that in the TweakTool, but it only seems to accept integers as scaling factor.

Does anybody know about a workaround for this? Scaling by two is way too large for my screen. The value I want is closer to 1.2

Any help will be greatly appreciated!

Answer 1

I checked with my Fedora 21 install where I have Gnome 3.14.2 and it doesn't seem to be possible to set your desired value:

[btegge@za21 ~]$ gsettings set org.gnome.desktop.interface scaling-factor 1.2
invalid character in number:
  1.2
   ^
[btegge@za21 ~]$ gsettings set org.gnome.desktop.interface scaling-factor 1,2
expected end of input:
  1,2
   ^

My assumptions:

• There is a another setting to achieve what you want. The only thing that comes to my mind is font rendering related, though that is not exactly what you are looking for.
• It's a mistake that the key only accepts integers as datatype and you should file a bug.

Answer 2

I am not sure if this got resolved or not, but there are two scaling options in Gnome to achieve this. The "window scaling" attribute that you are doing either accepts 1 or 2 (or 0, but this is "undefined" I think). If you want, you can do text scaling, which accepts floating numbers.

In Gnome Tweak Tool, this is available under the font section. Alternatively, you can access both in the dconf-editor under org.gnome.desktop.interface I have noticed this option tends to work better, as Gnome Tweak Tool can sometimes not update setting correctly, causing weird scaling issues.

Answer 3

Fractional scaling is not officially supported on versions lower than 3.32 and not supported at all inside GNOME in versions lower than 3.28.

You can neverthless obtain the same effect on 3.16 with xrandr.

Answer 4

You can do it if you switch to the Wayland display server: https://www.omgubuntu.co.uk/2017/09/enable-fractional-scaling-gnome-linux

Otherwise, your only option would seem to be to upgrade to a version of the distro with a newer version of GNOME. This functionality is available in Ubuntu 19.04: https://www.omgubuntu.co.uk/2019/06/enable-fractional-scaling-ubuntu-19-04

Answer 5

Non-integer scaling is not (yet) supported in Gnome and therefore Ubuntu. Athough, it is possible to achieve with some workarounds using xrandr, which involves an upscaling and a subsequent downscaling, I cannot recommend this as it is very CPU/GPU intensive and comes with other quirks and problems and does not necessarily lead to the desired result. There are a lot of ongoing debates and argues on r/linux over at reddit if you are interested and here is also an article from one of the elementary devs (a distro based on Ubuntu) who talks a bit more about High DPI in depth: link. Hope this helps a bit.