dmkuk / libwacom

libwacom is a tablet description library

Overview

libwacom is a library to identify graphics tablets and their model-specific features. It provides easy access to information such as "is this a built-in on-screen tablet", "what is the size of this model", etc.

The name libwacom is historical - it was originally developed for Wacom devices only but now supports any graphics tablet from any vendor.

libwacom does not make a tablet work. libwacom is merely a database with a C library wrapper for information about a tablet. It has no effect on whether that tablet works.

libwacom is currently used by GUI toolkits (GNOME, KDE, others?) to map built-in tablets to the correct screen and by libinput to determine configuration options such as the left-handed settings. SVG layout files are used to describe tablet visually.

Adding tablet descriptions to libwacom

A common indicator that a device is not supported by libwacom is that it works normally in a GNOME session, but the device is not correctly mapped to the screen.

Use the libwacom-list-local-devices tool to list all local devices recognized by libwacom. If your device is not listed, but it is available as an event device in the kernel (see /proc/bus/input/devices) and in the X session (see xinput list), the device is missing from libwacom's database. Use the libwacom-list-devices tool to list all known devices and verify the tablet is not in that list.

To add support for a new tablet to libwacom git:

1. Create a new tablet definition file. See data/wacom.example in the source for a guideline on how to add a new tablet. For an installed version of libwacom, see the existing data files (e.g. /usr/share/libwacom/cintiq-13hd.tablet)
2. A new tablet description is enabled by adding and installing a new file with a .tablet suffix. Once installed the tablet is part of libwacom's database, no rebuild is necessary
3. The tablet is then available through libwacom-list-local-devices

You must update udev after installing the file, see below.

To add support for a tablet to an installed libwacom

If the system-provided libwacom does not include a .tablet file, it is possible to "backport" that .tablet file to the system-provided libwacom.

libwacom 1.10 and newer

Copy the .tablet file into /etc/libwacom and run the libwacom-update-db tool. Copy the tablet's .svg layout file to /etc/libwacom/layouts.

$ cp my-tablet-file-from-upstream.tablet /etc/libwacom/
$ cp my-tablet-file-layout.svg /etc/libwacom/layouts/
$ libwacom-update-db /etc/libwacom

The tool will take care of updating udev, the hwdb, etc.

libwacom 1.9 and earlier

For versions of libwacom <= 1.9, the file must be copied to /usr/share/libwacom. It may be overwritten on updates.

You must update udev after installing the file. The simplest (and broadest) way to do this is outlined below:

# create the hwdb file
$ cat <EOF > /etc/udev/hwdb.d/66-libwacom.hwdb
# WARNING: change "Your Device Name" to the actual name of your device
libwacom:name:Your Device Name*:input:*
 ID_INPUT=1
 ID_INPUT_TABLET=1
 ID_INPUT_JOYSTICK=0

libwacom:name:Your Device Name Pad:input:*
 ID_INPUT_TABLET_PAD=1

# Use this if the device is an external tablet
libwacom:name:Your Device Name Finger:input:*
 ID_INPUT_TOUCHPAD=1

# Use this if the device is a screen tablet
libwacom:name:Your Device Name Finger:input:*
 ID_INPUT_TOUCHSCREEN=1

EOF
$ systemd-hwdb --update

Now disconnect and reconnect the device and it should be detected by libwacom.

API Documentation

The API documentation is available at https://linuxwacom.github.io/libwacom/