Gel-O

Gel-O is a library that provides a std::Iterator interface over Linux InputEvents. You can map, filter and loop over input events without dealing with the low-level details of obtaining those events.

Gel-O is so named for examples/delay.rs, which delays all user input, making a computer feel like Jell-O.

Stability

Gel-O is experimental. Expect many breaking changes to come.

Similar crates

• evdev
  • A pure-rust Iterator over InputEvents, with no support for writing to devices (simulating user input).
• evdev-rs
  • Low-level safe bindings to libevdev. Gel-O is built atop evdev-rs.

Requirements

• Linux
  • epoll (Linux 2.6.27+)
  • kernel supporting evdev (~ 2.4+)
• Rust toolchain
  • version 1.40 or higher
  • cargo
• Transitive dependencies
  • C toolchain
  • autoconf and libtool
    • #apt install autoconf libtool
    • #yum install autoconf libtool
    • #pacman -S autoconf libtool

macOS and Windows are not supported and support is not planned. BSD support may be easy to add, as evdev was recently added to FreeBSD.

FAQ

• How does it work?
  • Gel-O monitors device files in /dev/input, reading InputEvents lazily only when user code calls .next().
• Does it work when using the Wayland Display Server Protocol?
  • Yes. Gel-O works everywhere linux does - on Xorg, Wayland, and even the Linux virtual terminal
• What is the computational overhead of Gel-O?
  • Gel-O is pretty leightweight. Most of the examples use around 1MB of RAM. Mouse movement is smooth on low-power devices (such as Raspberry Pi) due to efficient epoll-based architecture. On raspberry pi 3, expect Gel-O to use ~2% CPU during rapid mouse movement and 0% otherwise.
• What devices does Gel-O work with?
  • Gel-O works with every input device Linux does because Gel-O operates just above the driver level. Gel-O has been tested specifically with mice, keyboards, power buttons and gamepads.
• What happens if I unplug my device and plug it back in?
  • Gel-O detects new devices being plugged in, and starts monitoring them. Unplugging and plugging in might mean a few events are lost, but everything will continue smoothly after that loss.

Limitations

• Requires read/write access to files in /dev/input and the file /dev/uinput
  • This can be acomplished by running as root (sudo)

Developing

Download the source

git clone [this repo]

Compile the source. You need a rust toolchain and cargo.

cargo build --release --example delay

Run the produced binary with root privledges

sudo ./target/release/examples/delay [number of ms to delay]

make changes to source files. Before committing, run checks.sh (this checks formatting and for compiler warnings) and test you changes locally

./checks.sh && cargo test --no-run && sudo --preserve-env cargo test