# gotta-scroll-fast

Host-side **scroll acceleration** toolkit for Linux/Wayland.

This project is a fork/reimplementation inspired by [maccel](https://github.com/Gnarus-G/maccel), but it is a **separate tool** focused on scroll acceleration.

## credit and licensing

- Original inspiration/source: https://github.com/Gnarus-G/maccel
- Attribution details: `NOTICE.md`
- License: **GPL-2.0-or-later** (`LICENSE`)

## components

- `gsf` - parameter CLI + TUI
- `gsfd` - evdev -> uinput scroll acceleration daemon
  - applies acceleration curves to wheel/hwheel (including hi-res wheel events)
  - suppresses low-res wheel duplicates when hi-res events are present in the same frame

## development

```bash
nix develop
cargo build
```

## quick start (functional)

1) List devices:

```bash
cargo run -p gsf-daemon -- --list-devices
```

2) Pick your trackball device and run dry-run first:

```bash
cargo run -p gsf-daemon -- --device /dev/input/eventX --dry-run
```

3) Tune parameters (separate terminal):

```bash
cargo run -p gsf-cli -- set mode natural
cargo run -p gsf-cli -- set param sens-mult 1.0
cargo run -p gsf-cli -- set param decay-rate 0.1
cargo run -p gsf-cli -- set param limit 1.5
```

or launch TUI:

```bash
cargo run -p gsf-cli -- tui
```

4) Run live daemon:

```bash
cargo run -p gsf-daemon -- --device /dev/input/eventX
```

Tip: auto-pick by name substring:

```bash
cargo run -p gsf-daemon -- --match-name ploopy
```

## config + state paths

Default config path:
- `~/.config/gsf/config.json`
- override with `GSF_CONFIG_PATH`

Default speed stats path:
- `$XDG_RUNTIME_DIR/gsf-speed.txt` (if available)
- fallback `~/.local/state/gsf/speed.txt`
- override with `GSF_STATS_PATH`

## runtime requirements

- Linux with evdev/uinput
- `/dev/uinput` available
- permissions to read source event device and write uinput

For NixOS notes, see `DEV_SETUP.md`.

## systemd user service

A starting unit file exists at:

- `packaging/systemd/user/gsfd.service`

Copy to `~/.config/systemd/user/gsfd.service`, adjust device selection args, then:

```bash
systemctl --user daemon-reload
systemctl --user enable --now gsfd
```