https://github.com/petercxy/scroll-emulation
Middle button scrolling emulation for Wayland (tested on GNOME Wayland)
https://github.com/petercxy/scroll-emulation
emulation gnome scroll wayland
Last synced: 3 months ago
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Middle button scrolling emulation for Wayland (tested on GNOME Wayland)
- Host: GitHub
- URL: https://github.com/petercxy/scroll-emulation
- Owner: PeterCxy
- Created: 2017-12-02T03:04:35.000Z (almost 8 years ago)
- Default Branch: master
- Last Pushed: 2022-04-27T20:48:27.000Z (over 3 years ago)
- Last Synced: 2025-06-28T02:01:59.207Z (3 months ago)
- Topics: emulation, gnome, scroll, wayland
- Language: C
- Size: 3.91 KB
- Stars: 30
- Watchers: 5
- Forks: 4
- Open Issues: 4
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
A simple hack to use middle button scrolling emulation under GNOME Wayland (and other Wayland compositors that do not expose `libinput` configuration). This is tested with my GPD Pocket, whose trackpoint does not have a middle button thus cannot scroll by default (after applying this hook, I can use right button + cursor to emulate scrolling)
Simply clone this repo and run
```bash
gcc -shared -ldl -linput -fPIC hook.c -o hook.so
```
which will generate a `hook.so` in the current directory.
Then add this `hook.so` to your LD\_PRELOAD (use `/etc/profile.d` or `/etc/profile` in order to make it usable to GNOME Wayland)
e.g. You could add content like this to `/etc/profile.d/libinput.sh`
```bash
export LD_PRELOAD="$LD_PRELOAD /path/to/your/hook.so"
```
replace `/path/to/your/hook.so` with the __absolute path__ to your `hook.so`.
Reboot and enjoy. (Press right button and move the cursor = scrolling)
How does it work
===
It is very simple. The `libinput` library itself already contains code to emulate scrolling. Under Xorg we can use configuration like this
```
Driver "libinput"
Option "MiddleEmulation" "1"
Option "ScrollButton" "3"
Option "ScrollMethod" "button"
```
To enable this built-in feature. Even if some Wayland compositors do not expose such configuration, the functionality is still available thanks to `libinput`. All we need to do is to find a way to force apply these options to the devices.
Therefore, I tried to find a function that has `libinput_device` as a parameter and will be always called. One of them is `libinput_device_get_name`. This is what `hook.c` does: hook into this function and force set the needed configuration on every possible device. Since the compositors will load `/etc/profile` regardlessly, we will now have working scrolling emulation.
It might be better if something could be done to force expose those configuration options through `LD_PRELOAD`. This is not difficult, but I'm not doing it now because it seems enough for me right now :).