Development

Contributions are very welcome, I will gladly review and discuss any merge requests. This file should give an overview about some notable internals of key-mapper.

Roadmap

show a dropdown to select valid devices
creating presets per device
renaming presets
show a mapping table
make that list extend itself automatically
read keycodes with evdev
inject the mapping
keep the system defaults for unmapped buttons
button to stop mapping and using system defaults
highlight changes and alert before discarding unsaved changes
automatically load presets on login for plugged in devices
make sure it works on wayland
support timed macros, maybe using some sort of syntax
add to the AUR, provide .deb file
basic support for gamepads as keyboard and mouse combi
executing a macro forever while holding down the key using h
mapping D-Pad directions as buttons
configure joystick purpose and speed via the GUI
support for non-GUI TTY environments with a command to stop and start
start the daemon in such a way to not require usermod
mapping a combined button press to a key
add "disable" as mapping option
mapping joystick directions as buttons, making it act like a D-Pad
mapping mouse wheel events to buttons
automatically load presets when devices get plugged in after login (udev)
map keys using a modifier + modifier + ... + key syntax
inject in an additional device instead to avoid clashing capabilities
don't run any GTK code as root for wayland compatibility
injecting keys that aren't available in the systems keyboard layout
ship with a list of all keys known to xkb and validate input in the gui

Tests

sudo pip install coverage
pylint keymapper --extension-pkg-whitelist=evdev
sudo pip install . && coverage run tests/test.py
coverage combine && coverage report -m

To read events, evtest is very helpful. Add -d to key-mapper-gtk to get debug output.

Single tests can be executed via

python3 tests/test.py test_paths.TestPaths.test_mkdir

Releasing

ssh/login into a debian/ubuntu environment

./scripts/build.sh

This will generate key-mapper/deb/key-mapper-0.7.0.deb

Badges

sudo pip install git+https://github.com/jongracecox/anybadge
./scripts/badges.sh

New badges, if needed, will be created in readme/ and they just need to be commited.

Files

gui

bin/key-mapper-gtk the executable that starts the gui. It also sends messages to the service via dbus if certain buttons are clicked.
bin/key-mapper-gtk-pkexec opens a password promt to grant root rights to the GUI, so that it can read from devices
data/key-mapper.policy configures pkexec
data/key-mapper.desktop is the entry in the start menu

cli

bin/key-mapper-control is an executable to send messages to the service via dbus. It can be used to start and stop injection without a GUI.

service

bin/key-mapper-service executable that starts listening for commands via dbus and runs the injector when needed. It shouldn't matter how it is started as long as it manages to start without throwing errors. It usually needs root rights.
data/key-mapper.service starts key-mapper-service automatically on boot on distros using systemd.
data/keymapper.Control.conf is needed to connect to dbus services started by systemd from other applications.

autoload

data/key-mapper-autoload.desktop executes on login and tells the systemd service to stop injecting (possibly the presets of another user) and to inject the users autoloaded presets instead (if any are configured)
data/key-mapper.rules udev rule that sends a message to the service to start injecting for new devices when they are seen for the first time.

Example system startup

systemd loads key-mapper.service on boot
on login, key-mapper-autoload.desktop is executed, which has knowledge of the current user und doesn't run as root
2.1 it sends the users config directory to the service
2.2 it makes the service stop all ongoing injectings
2.3 it tells the service to start loading all of the configured presets
a bluetooth device gets connected, so udev runs key-mapper.rules which tells the service to start injecting for that device if it has a preset assigned. Works because step 2 told the service about the current users config.

Communication to the service always happens via key-mapper-control

Unsupported Devices

Either open up an issue or debug it yourself and make a pull request.

You will need to work with the devices capabilities. You can get those using

sudo evtest

It tries or doesn't try to map ABS_X/ABS_Y

Is the device a gamepad? Does the GUI show joystick configurations?

if yes, no: adjust is_gamepad to loosen up the constraints
if no, yes: adjust is_gamepad to tighten up the constraints

Try to do it in such a way that other devices won't break. Also see readme/capabilities.md

It won't offer mapping a button

Modify should_map_as_btn

How it works

It uses evdev

It grabs a device (e.g. /dev/input/event3), so that the key events won't reach X11/Wayland anymore source
Reads the events from it (evtest can do it, you can also do cat /dev/input/event3 which yields binary stuff) source
Looks up the mapping if that event maps to anything source
Injects the output event in a new device that key-mapper created (another new path in /dev/input, device name is suffixed by "mapped") source, new device
Forwards any events that should not be mapped to anything in another new device (device name is suffixed by "forwarded") source, new device

This stuff is going on as a daemon in the background

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