wacomCQpro — Wacom Express Key Remote → keyboard shortcuts daemon

Pure-Rust daemon that reads a Wacom Express Key Remote pad via evdev and injects keyboard shortcuts and scroll events via a uinput virtual device.

Replaces input-remapper (3 × python3 processes, 84 MB RSS) with a single Rust binary (~600 KB RSS).

Requirements

• Linux with /dev/uinput (kernel module uinput)
• Read/write access to /dev/uinput and Wacom input devices
• notify-send from libnotify (mode-switch popups)
• GTK4 (optional, for wacomCQpro gui)

Quick start

cargo build --release
cp target/release/wacomCQpro ~/.local/bin/
wacomCQpro status    # show pad layout + current mappings
wacomCQpro run       # start daemon

Build without GUI (daemon only, fewer dependencies):

cargo build --release --no-default-features

Arch Linux install

From the repo root (the directory containing PKGBUILD):

makepkg -si
systemctl --user enable --now wacomCQpro

Note: This PKGBUILD builds in-tree (source=()). Run makepkg from the project root so Cargo output lands in ./target/release/.

This installs the binary, systemd user unit, and udev rule for /dev/uinput. Add your user to the input and uinput groups, then log out and back in:

sudo usermod -aG input,uinput "$USER"

Commands

Command	Description
wacomCQpro run	Start the daemon (default)
wacomCQpro status	Show pad schematic + all 18 buttons + current mappings
wacomCQpro identify	Press keys/turn the ring; prints the BTN_* name to use for each
wacomCQpro validate	Check config for errors
wacomCQpro reload	Reload config in running daemon
wacomCQpro edit	Open config in $EDITOR
wacomCQpro gui	Graphical config editor — a labeled schematic (each key shows its BTN_* code, mapping, and action description) with a Learn buttons mode that lights up the key you press + ring modes
wacomCQpro --version	Print version
wacomCQpro help	Show help

Configuration

Config lives at ~/.config/wacomCQpro/config.toml — created automatically on first run with defaults. Edit button mappings and ring modes freely.

[buttons]
BTN_0     = "cycle_ring_mode"
BTN_1     = "Ctrl+Alt+8"
BTN_Z     = "M"

[[ring_mode]]
name = "Brush Size"
cw   = "scroll_up"
ccw  = "scroll_down"

[[ring_mode]]
name = "Zoom"
cw   = "Ctrl+Equal"
ccw  = "Ctrl+Minus"

Buttons (all 18): BTN_0–BTN_9, BTN_A, BTN_B, BTN_C, BTN_X, BTN_Y, BTN_Z, BTN_BASE, BTN_BASE2. Not sure which physical key is which? Open wacomCQpro gui, click Learn buttons, and press each one (it lights up the matching key) — or from a terminal run wacomCQpro identify.

Key names: single letters (A–Z), numbers (0–9), Ctrl, Shift, Alt, Super, Equal, Minus, LeftBrace, RightBrace, Space, Tab, Return, Escape, Delete, Backspace, Left, Right, Up, Down, F1–F12.

Combos: "Ctrl+Z", "Ctrl+Shift+Z", "Ctrl+Alt+8"

Special actions: "cycle_ring_mode", "scroll_up", "scroll_down"

Button descriptions: Optionally add human-readable action names in a [button_desc] section — shown in the GUI beneath each key's mapping entry:

[button_desc]
BTN_1 = "Eraser toggle"
BTN_3 = "Undo"

The daemon reloads config automatically when config.toml changes (within ~1s), or immediately via wacomCQpro reload. Invalid configs are rejected and the previous mappings are kept.

The GUI draws the remote as a labeled schematic: a touch ring with the center (mode) button inside it, then the remaining 17 keys as a grid. Each key shows its BTN_* code with an inline mapping entry and an action description beneath it — the picture is the editor, so there's no guessing which key a field controls or what it does. Clearing a field unmaps that button. Ring modes are edited alongside it; Save validates before writing.

Learn buttons: don't know which physical key is BTN_3? Click Learn buttons and press a key on the remote — its keycap lights up and the status line names it. The daemon grabs the pad exclusively, so the GUI stops it for the duration of Learn mode and restarts it automatically when you turn Learn off or close the window.

Target hardware

Device	USB ID
Wacom Cintiq Pro 24 Pen (056a:037c)	built-in USB
Wacom Express Key Remote (056a:0331)	bundled dongle

Device auto-detection

Scans /dev/input/ for Wacom vendor (0x056a) devices with "Pad" in the name. Prioritizes devices with ABS_WHEEL (touch ring). Reconnects automatically on USB disconnect/reconnect.

Button layout

The Express Key Remote exposes 18 buttons (BTN_0–BTN_9, BTN_A/B/C/X/Y/Z, BTN_BASE/BTN_BASE2) — all remappable. The schematic below names the most commonly used ones; run wacomCQpro identify to learn the exact code for every physical key on your unit.

  ┌─────────────────────────────────┐
  │          [BTN_Z]                │  top
  ├─────┬───────────────────┬───────┤
  │     │                   │       │
  │BTN_1│     [BTN_0]       │ BTN_4 │  center ring
  │     │   (cycle mode)    │       │
  │     │                   │       │
  ├─────┴───────────────────┴───────┤
  │          [BTN_BASE2]            │  upper-mid
  │          [BTN_BASE]             │  lower-mid
  ├─────────────────────────────────┤
  │          [BTN_C]                │  bottom
  └─────────────────────────────────┘

Touch ring (ABS_WHEEL)

The ring reports position 1–71 while touched and 0 when your finger is off it; the daemon emits one step per position change and ignores the landing/lift transitions (so releasing your finger never fires a stray scroll). Three cycling modes, toggled by pressing the center ring (mode) button:

Mode	Clockwise	Counter-clockwise
Brush Size	REL_WHEEL +1	REL_WHEEL -1
Zoom	Ctrl++	Ctrl+-
Rotate Canvas	]	[

Architecture

USB dongle → /dev/input/eventN (auto-detected)
       │
       ▼  EVIOCGRAB (exclusive access)
  wacomCQpro daemon
       │
       ├── ABS_WHEEL deltas → uinput REL_WHEEL / key combos
       └── KEY events (BTN_*) → uinput key combos
       │
       ▼
  uinput virtual device (/dev/input/eventN)
       │
       ▼
  Hyprland / Krita / any app

systemd

User service installed by the PKGBUILD or manually:

# ~/.config/systemd/user/wacomCQpro.service
[Service]
ExecStart=%h/.local/bin/wacomCQpro run
Restart=on-failure

systemctl --user enable --now wacomCQpro

Files

Path	Purpose
~/.config/wacomCQpro/config.toml	Button + ring mappings
~/.config/wacomCQpro/wacomCQpro.lock	Daemon PID lock file
/usr/bin/wacomCQpro	Installed binary (PKGBUILD)
/usr/lib/systemd/user/wacomCQpro.service	systemd user unit

Debug

wacomCQpro status                          # config + detected device
evtest "$(wacomCQpro status | awk '/Device:/{print $2}')"
grep -A5 "wacomCQpro" /proc/bus/input/devices
systemctl --user status wacomCQpro

License

MIT — see LICENSE.