gKeyMapper/README.md

# gKeyMapper

![C++17](https://img.shields.io/badge/C%2B%2B-17-00599C?logo=cplusplus&logoColor=white)
![GTK 4](https://img.shields.io/badge/GTK-4-7FE719?logo=gtk&logoColor=black)
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![libusb](https://img.shields.io/badge/libusb-1.0-c8a200)
![xkbcommon](https://img.shields.io/badge/xkbcommon-layout--aware-6E4C13)
![i18n](https://img.shields.io/badge/i18n-de%20%7C%20en%20%7C%20es%20%7C%20fr-blueviolet)
![systemd](https://img.shields.io/badge/systemd-user%20service-30D475?logo=systemd&logoColor=white)
![Platform](https://img.shields.io/badge/platform-Linux%20Mint%20%7C%20Ubuntu-FCC624?logo=linux&logoColor=black)

GTK4 application (C++) for remapping the G keys **G1–G9** of a Logitech **G910**
to other keys or commands (Linux Mint / Ubuntu).

The GUI is complete. The background daemon (`gkeymapper-daemon`) that reads the
G-keys from the keyboard and replays the actions is implemented as well; the
GUI and the daemon talk over a small D-Bus channel (status, reload, test) — see
`docs/daemon-plan.md`.

**Only the daemon has to run.** It is the part that reads the G keys and replays
the action, and it runs as a systemd user service. The window is for editing the
mappings and for the status: it may be closed at any time, and starting it with
the session (`Options` → `Start with the session`) is a convenience, not a
requirement.

Documentation and source comments are written in English.

## Requirements

- Linux Mint / Ubuntu
- g++ (C++17)
- pkg-config
- gettext (for translations, `msgfmt`)
- GTK 4 development files
- libusb 1.0 development files (for the daemon)
- libxkbcommon development files (for the daemon's layout handling)
- GLib/GIO development files (for the GUI ↔ daemon D-Bus channel; `libgtk-4-dev`
  already pulls them in, but they are needed for `make daemon` on its own)

### Install dependencies

```bash
sudo apt update
sudo apt install -y build-essential gettext libgtk-4-dev libusb-1.0-0-dev libxkbcommon-dev libglib2.0-dev
```

Afterwards `pkg-config --modversion gtk4`, `pkg-config --modversion libusb-1.0`
and `pkg-config --modversion gio-2.0` should print versions.

## Setting up the project

Change to the project directory:

```bash
cd /home/trager/Nextcloud/Projekte/C++/gKeyMapper
```

(Alternatively clone the repository or copy the project folder to your own location.)

## Build

```bash
make
```

This produces the `gkeymapper` GUI binary, the `gkeymapper-daemon` binary and
the `.mo` translations under `locale/`. The daemon can also be built on its own
with `make daemon`. The GUI has its icons (`assets/icon.png`, `assets/icon.svg`)
compiled in (`data/icons.gresource.xml` → generated `build/gresources.c`), so the
window icon works without an installed `assets/` directory.

## Rebuild translations

```bash
make translations
```

## Run

Normal:

```bash
./gkeymapper
```

With explicit language files (useful for testing from the build directory):

```bash
LANG=de_DE.UTF-8 GKEYMAPPER_LOCALEDIR=$PWD/locale ./gkeymapper
```

Supported languages: German, English, Spanish, French.

The footer of the window shows the daemon state (`Daemon: running · Device: …`
plus the last G key that fired, or `Daemon: not reachable`) and follows it live:
start or stop the daemon while the GUI is open and the line updates itself. Two
more states are reported explicitly: `Device: not found` (the daemon is up but
has no keyboard) and `Configuration error` (a reload failed, so the daemon kept
the mappings it had).

The window starts from the saved mappings: it loads
`~/.config/gKeyMapper/mappings.conf` when it opens, so `Save mappings` in a fresh
window rewrites the same content instead of emptying the file.

Only one window is open at a time, and it is the one you just started: a new
start closes the instance that is already running — including one from an older
build — and then shows its own window, so a stale window can never stay next to a
fresh one. Row edits that were not saved are lost with the replaced window,
because saving is always explicit (`Save mappings`).

### Menu, tray icon and minimize to tray

The menu button in the title bar holds `Export configuration...` / `Import
configuration...`, `Options`, `Help` (also `F1`), `About` and `Quit` (`Ctrl+Q`).

* `Help` opens a one-page explanation of the nine rows, the four types, the
  capture dialog, the daemon status and the tray.
* `Options` opens a small window with the GUI's own switches and the daemon in
  detail: state, version, keyboard, the config file it reads and the last G key
  that fired (the footer says the same in one line). The window is not modal, so
  it keeps updating while it is open. One of its switches is the language
  (`System language`, or a fixed `de`/`en`/`es`/`fr`): it switches the window, the
  menus and the tray menu right away — nothing to restart, and rows that were not
  saved yet are kept.
* `Start with the session` opens the window when you log in. It writes the usual
  autostart entry (`~/.config/autostart/gkeymapper.desktop`, starting the binary
  that is running) and removes it again when you switch it off; an entry that the
  desktop's own startup tool has disabled counts as off, too. Like the window
  itself this is a convenience: the G keys do not need it, only the daemon has to
  run (see `Running the daemon` below).

`Minimize to tray` keeps gKeyMapper reachable from the panel: the window is
hidden instead of closed when you close or minimize it, and the tray icon's menu
shows it again (`Show`) or quits the program (`Close`). Closing still quits when
the option is off — or when no panel hosts the tray icon, because then there
would be no way back to the window. The option is remembered in
`~/.config/gKeyMapper/gui.conf`, a file of its own so `mappings.conf` stays a
pure mapping file. The same file holds the chosen language; with `System
language` (the default) the desktop's locale decides.

The tray icon is a StatusNotifierItem plus a `com.canonical.dbusmenu` menu over
GIO — the same protocol libxapp and libappindicator wrap, only without their GTK3
dependency (a GTK4 process must not load GTK3). It needs no package of its own and
works wherever the protocol is hosted: the Cinnamon panel (via `xapp-sn-watcher`),
KDE, Unity or GNOME with the AppIndicator extension. The icon travels as a pixmap
because the panel is a different process and cannot read the icons compiled into
the binary.

## Running the daemon

The daemon reads G1–G9 from the keyboard and replays the configured action
(`key` through a virtual keyboard, `command` by launching the program):

```bash
./gkeymapper-daemon                 # uses ~/.config/gKeyMapper/mappings.conf
./gkeymapper-daemon /path/to.conf   # or an explicit file
```

- It reaches the keyboard through libusb (raw USB HID, vendor interface 1) and
  creates a virtual keyboard via `/dev/uinput`. Both need access for your user;
  `make install` ships a udev rule (`TAG+="uaccess"`) for that. On Linux Mint the
  device already has such an ACL, otherwise install the rule or add your user to
  the `input`/`uinput` group.
- The media keys (mute / volume / play / next / previous / stop) keep working
  while it runs. The keyboard delivers them on the vendor interface — as a second
  kernel input device (`…/input1`, the "… G910 Keyboard" consumer device) when the
  daemon is *not* running — so the daemon picks those reports up and forwards them
  unchanged through its virtual keyboard. There is nothing to configure; they
  behave exactly as they do without the daemon.
- The mappings file is **watched**: save in the GUI and the daemon picks the
  change up by itself (within about half a second), no restart and no signal.
  `SIGHUP`/`SIGUSR1` reload it on demand, which is also the fallback on systems
  without inotify:

  ```bash
  kill -HUP $(pgrep -x gkeymapper-daem)
  ```

  Note: the kernel truncates the process name to 15 characters, so
  `pgrep -x gkeymapper-daemon` does **not** match.
- A failed reload keeps the previous mappings, so a transient read error never
  silently disables every key. The GUI shows it as `Configuration error` in the
  footer.
- It does **not** need the keyboard to be present: when it is unplugged (or not
  there yet when the session starts) the daemon keeps running, reports
  `Device: not found` and looks for it again every 2 s. A re-plug needs no
  restart and keeps the GUI connection.
- A G key fires when its report first shows it as pressed: holding it down does
  not repeat the action, and two G keys held at once both fire (the report
  carries the state of all nine keys, not one key per report).
- `keyhold` is the exception to that: its keys stay pressed for as long as the G
  key is held, like a normal key (including the desktop's auto-repeat), so a game
  or a push-to-talk sees a key that is down exactly as long as you hold the G key.
  The keyboard's release report ends it. If the keyboard is unplugged or the
  daemon stops while a key is held, the daemon lets it go, so nothing stays stuck.
  Holding only makes sense for a single step: `keyhold:ctrl+w` is held,
  `keyhold:ctrl+c,ctrl+v` is replayed as a tap (the log says so).
- Only one instance may run: a second one prints why it cannot get the bus name
  and exits, instead of fighting over the keyboard and creating a second virtual
  keyboard.
- Key names are layout-independent: `key:ctrl+z` means the key that produces
  `z` **on your layout**. The layout is read from `/etc/default/keyboard`
  (`XKBLAYOUT`); without it, US key positions are used. Because the name is
  symbolic, the same entry keeps its meaning if the layout changes (as long as
  the layout has that key); a name the layout does not provide is skipped.
- `altgr+...` presses AltGr (level 3), e.g. `key:altgr+7` types `{` on a German
  layout.
- `command:...` is run through the shell, so arguments work
  (`command:/usr/bin/firefox --new-window`); a plain program path is also fine.
  It inherits the environment of the user service, i.e. of your desktop session —
  `DISPLAY`, `XAUTHORITY` and `PATH` are already there on a normal setup. If a
  command cannot reach the display, export them into the user manager:

  ```bash
  systemctl --user import-environment DISPLAY WAYLAND_DISPLAY XAUTHORITY
  systemctl --user show-environment | grep DISPLAY
  ```

Stop it with Ctrl+C or `kill`; it reattaches the kernel driver on the way out.

### Status and control over D-Bus

The daemon owns the name `dev.rager.gkeymapper.Daemon` on the session bus. The
GUI uses that channel for its footer line ("Daemon: running / not reachable",
the device and the last G key that fired) and to apply a save immediately.
Nothing on this channel is on the keypress path, so a GUI that is slow or absent
never delays an action.

```bash
D=dev.rager.gkeymapper.Daemon
O=/dev/rager/gkeymapper/Daemon

gdbus call --session --dest $D --object-path $O --method $D.GetStatus
gdbus call --session --dest $D --object-path $O --method $D.Reload
gdbus call --session --dest $D --object-path $O --method $D.TestMapping 0
gdbus monitor --session --dest $D      # KeyPressed / ConfigReloaded / DeviceChanged
```

- `GetStatus` → `(version, running, device, configPath)`.
- `Reload` re-reads the mappings file; `ConfigReloaded(ok)` reports the result.
- `TestMapping` fires a mapping without touching the keyboard (useful to check a
  sequence). The index is **0-based**: `0` = G1 … `8` = G9. It runs the same code
  path as a real keypress.
- `KeyPressed(index, action)` is emitted for every G key, real or tested.

If no session bus is available the daemon still works — it just runs without the
GUI channel and logs that.

## Install (optional)

```bash
sudo make install
```

Installs, under `PREFIX` (default `/usr/local`):

| Path | What |
|---|---|
| `bin/gkeymapper`, `bin/gkeymapper-daemon` | the GUI and the daemon |
| `share/locale/*/LC_MESSAGES/gkeymapper.mo` | translations |
| `share/gkeymapper/assets/`, `share/applications/`, `share/icons/` | icon, `.desktop` file, icons |
| `lib/udev/rules.d/60-gkeymapper.rules` | lets your user reach the keyboard and `/dev/uinput` |
| `lib/modules-load.d/gkeymapper.conf` | loads the `uinput` module at boot |
| `lib/systemd/user/gkeymapper-daemon.service` | systemd user unit (binary path filled in from `PREFIX`) |
| `share/dbus-1/services/dev.rager.gkeymapper.Daemon.service` | D-Bus activation: the GUI can start the daemon on demand |

Then enable the daemon for your session — it then starts automatically at login:

```bash
systemctl --user daemon-reload
systemctl --user enable --now gkeymapper-daemon
systemctl --user status gkeymapper-daemon
```

Enabling it is optional: the D-Bus activation file above lets the bus start the
daemon as soon as the GUI asks for its status. With both in place the unit is
used either way, so the daemon never runs twice.

It is a **user** service on purpose: it needs your session for `/dev/uinput` and
so that a `command` action inherits `DISPLAY`/`WAYLAND_DISPLAY`. The unit does
not run as root. `make install` reloads the udev rules for you; on a fresh
machine replug the keyboard (or reboot) once so the ACL applies.

## Clean

```bash
make clean
```

Removes the binaries and the generated `locale/` and `build/` directories.

## Capturing key sequences

For rows of type **Key**, the action button opens a capture dialog:

- Press keys one after another; each press becomes one step.
- Modifier keys (Ctrl, Alt, Shift, Super) held during a press are recorded
  as part of that step.
- Each step stores the **base key** (the unshifted key), so `Shift`+ß is
  recorded as `shift+ssharp` and not as the shifted symbol `question`.
- AltGr (level 3) is recorded as the `altgr` modifier plus the base key, so
  `AltGr`+7 becomes `altgr+7`.
- The live preview shows the sequence. `Clear` resets it, `Done` writes it
  into the row, `Cancel` discards it.

The sequence uses the same format as
[g910-gkey-macro-support](https://github.com/JSubelj/g910-gkey-macro-support):
modifiers are joined with `+`, steps are separated with `,`
(e.g. `ctrl+c,ctrl+v` or `shift+f4,super+t`). The modifier order is
`ctrl`, `alt`, `shift`, `super`, `altgr`; parsing accepts any order.

## Configuration format

`Save mappings` writes `~/.config/gKeyMapper/mappings.conf`:

```
# gKeyMapper mappings (G1..G9)
G1=key:ctrl+c,ctrl+v
G2=command:/usr/bin/firefox
G3=disabled:
G4=keyhold:ctrl+w
```

The same format is used by Export/Import. `key` holds a captured shortcut
sequence and fires it once, `command` a program path or command line,
`disabled` ignores the G key, and `keyhold` keeps a single shortcut pressed for
as long as the G key is held (in the GUI it is the `Key (hold)` entry in the
Type dropdown). These map to the `shortcut` / `run` / `nothing` hotkey types of
the reference project; the native C++ daemon (`gkeymapper-daemon`) reads this
file and replays the actions — no Python involved.

`Save mappings` writes atomically (temporary file + `rename`), so the daemon
never sees a half-written file and the watch reloads exactly once per save.

## Project structure

```
src/main.cpp           # app actions + GUI + daemon status footer
src/keyrow.h           # KeyRow (one per G key)
src/mappings.{h,cpp}   # GUI glue: config file <-> row widgets
src/capturedialog.{h,cpp} # key-capture dialog
src/daemonclient.{h,cpp}  # D-Bus client for the daemon (status/reload)
src/singleinstance.{h,cpp} # one GUI only: a new start closes a running instance
src/trayicon.{h,cpp}   # tray icon: StatusNotifierItem + dbusmenu over GIO
src/settings.{h,cpp}   # gui.conf (window preferences, e.g. minimize to tray)
src/help.{h,cpp}       # help window
src/optionsdialog.{h,cpp} # options window: switches + detailed daemon status
shared/mapping.{h,cpp} # mappings format + shortcut parsing (GUI & daemon)
shared/keys.{h,cpp}    # canonical key names -> Linux key codes
shared/keymap.{h,cpp}  # layout-aware key lookups (xkbcommon), GUI + daemon
shared/ipc_ids.h       # app id + D-Bus names shared by GUI and daemon
daemon/main.cpp        # event loop: read G-keys, run the action
daemon/device_tables.{h,cpp}  # per-model raw HID report tables (G910)
daemon/g910_device.{h,cpp}    # libusb access to the vendor interface
daemon/uinput_keyboard.{h,cpp}# virtual keyboard for "key" mappings
daemon/action.{h,cpp}  # dispatch "key" / "command" / "disabled" / "keyhold"
daemon/config_watch.{h,cpp}   # inotify watch on mappings.conf (auto-reload)
daemon/ipc_dbus.{h,cpp}       # D-Bus service (status/reload/test/signals)
data/60-gkeymapper.rules      # udev rule (uaccess for device + /dev/uinput)
data/gkeymapper-uinput.conf   # modules-load.d fragment for uinput
data/gkeymapper-daemon.service# systemd user unit (installed by make install)
data/dev.rager.gkeymapper.Daemon.service # D-Bus activation (session bus)
docs/daemon-plan.md    # daemon plan (reference: g910-gkey-macro-support)
po/                    # Translations (pot/po/mo targets)
Makefile               # Build via pkg-config + gettext
.vscode/tasks.json     # VS Code tasks for make
README.md
```

## Troubleshooting

### `Package gtk4 was not found`

The GTK 4 development files are missing. Install them:

```bash
sudo apt install -y libgtk-4-dev
```

Then verify:

```bash
pkg-config --modversion gtk4
```

### `pkg-config` cannot find `.pc` files (wrong search path)

In some environments `PKG_CONFIG_PATH` must be set explicitly. Standard path on
Ubuntu/Mint:

```bash
export PKG_CONFIG_PATH=/usr/lib/x86_64-linux-gnu/pkgconfig:/usr/share/pkgconfig:/usr/lib/pkgconfig
```

## Planned next steps

- The M1–M3 / MR keys of the G910 and profiles: swap mapping sets on the fly,
  which is what the reserved `SetProfile` D-Bus method was meant for. Deliberately
  left for later (see `docs/daemon-plan.md` §11).
- Key sequence timing: per-step delays for recorded macros.
- `typeout`: type out a fixed text, like the reference project's action of that
  name — not decided yet (see §11).

## Not planned

- Remapping the media keys. The daemon forwards mute / volume / play / next /
  previous / stop unchanged, and that is meant to stay that way (see the note
  above): they are not G keys, so they get no rows in the GUI and no entry in the
  config file.