Trying out wayland

September 28, 2022

TL;DR

I switched to wayland from X11 as my daily driver and don’t regret it so far. It feels like it fixed more problems for me than introduced to the point I’d prefer not to switch back.

X11 and default DPI

I got my desktop monitor a few years ago. It is capable of 3840x2160 output (172 DPI). My integrated video card could do only 1920x1080 at most (78 DPI). I was a happy user of Xorg with default 96 DPI settings. I was using alacritty as a terminal with bitmap Terminus fonts carefully picked to avoid the need for glyph hinting.

X11 and HiDPI

About a year ago I updated my desktop machine. I chose cheap videocard that could output in 3840x2160 mode for my existing monitor. I wanted to look at the use of vector fonts in the terminal.

I switched to HiDPI mode on X11. Without the special configuration everything shrunk and became half the initial size! Arch Linux has a detailed overview of the knobs you can tweak to get most of Xorg environment upscaled: https://wiki.archlinux.org/title/HiDPI.

I tried hard not to configure too many things manually. I did font size Xft.dpi: 192 tweak via .Xresources. Pictograms in many applications (like claws-mail) didn’t pick up larger sizes. Mouse cursor became almost invisible. gtk-2 applications and older X11 applications that specify window sizes in pixels became unusable. I fixed cursor Xcursor.size: 64 via .Xresources. In applications (toolkits) without good support for DPI scaling I had to artificially increase font size and disabled pictograms in favour of text labels on buttons.

Surprisingly I had to abandon a few GUI apps in favour of their terminal equivalents as font scaling works so much better than UI element scaling!

The result was looking ok-ish. But after an active use I noticed sever tearing effect when I switch between workspaces. It was most pronounced when I switched from Firefox workspace (usually white background) to terminal workspace (black background). Tearing effect was a diagonal blocky zip line seen for a very short while. I mitigated it with Option "TearFree" "true" via xorg.conf. The mitigation only mostly removes tearing effect, but not fully. Diagonal line gets turned to horisontal line. The tearing frequency decreases to usable levels. But it was still noticeable.

Looking at the final X11 HiDPI setup:

the TTF fonts now looked great in terminals
the UI sizes were not quite the same, usually smaller, sometimes unreadable
some programs did not survive 2x downscaling and were too small to be useful at all
a bit of tearing effect was present

Wayland

I’ve been meaning to try wayland for a while but never had an excuse. I was afraid it will break too many applications I use frequently (or occasionally). I vaguely remembered horror stories from past years of things like wine not being able to track mouse cursor properly, possible videocard incompatibility problems (like nvidia). I also was afrad I was a too long-term Xorg user to easily accept minor changes I’ll face.

Having looked at the amount of tweaks I had to do for HiDPI and seeing recent An X11 Apologist Tries Wayland post I decided to give it a try.

I used i3 window manager in Xorg. Closest wayland sibling is sway. sway is mostly config-compatible with i3: it reads ~/.config/i3/config if ~/.config/sway/config does not exist. Thus the initial switch is trivial: just run sway.

wayland has a bit different way to handle DPI: it just assumes 96 DPI for programs that don’t handle scaling. User needs to specify the scale once for wayland. For me the magic command was wlr-randr --output DP-3 --scale 2 (or output DP-3 scale 2.0 via ~/.config/sway/config).

After that I got most old programs up to a reasonable size! It is s omething that X11 HiDPI could not do easily. That was a pleasant surprise. I even undid those rare changes I had to do for HiDPI on X11! Xwayland does a reasonable job of runnin many X11 programs as is. There are warts still.

Surprisingly under wayland tearing effect disappeared completely.

I switched to direct sway start from linux terminal. Before I used lightdm graphical login manager (modern X11 needed it for rootless mode for various reasons).

Not everything was ideal in wayland world. Some unexpected things I found:

xeyes background is garbled at start, issue known as https://github.com/swaywm/sway/issues/3395
clicking the links in terminal does not switch the focus to the browser, issues known as https://github.com/swaywm/sway/issues/4830
Ctrl+Enter does not work in mc (because it relies on X11 events). I’m slowly reading through https://wayland-book.com/ to get the idea where it should ideally be implemented: in the terminal, in mc or smewhere else.

Parting words

When I read through https://wayland-book.com/ I got a nice feling of being able to write nice smooth demos. Just like in DOS times when you could write pixels right into video RAM at the right VSYNC time (0x3da port). It’s probably no harder in X11. I never got to look at X11 MIT-SHM extension fearing of it’s lack of network transparency support. I spent some time playning with https://wayland-book.com/xdg-shell-basics/example-code.html example.

Architecturally wayland feels a lot like X11: both are RPC protocols over UNIX socket to interact with objects on the server asynchronously via requests and events. But the difference in the details is also startling: frame perfect design gives a great user experience, many things are a bit different that they used to be and require different solution.

I like sway/wayland experience so far and will try to port a few small things to it from X11/OpenGL.

Full sway config I got: https://github.com/trofi/home/blob/master/.config/sway/config.

Have fun!