Haptic/visual/audio feedback for GNOME

feedbackd provides a DBus daemon (feedbackd) to act on events to provide haptic, visual and audio feedback. It offers a library (libfeedback) and GObject introspection bindings to ease using it from applications.

License

feedbackd is licensed under the GPLv3+ while the libfeedback library is licensed under LGPL 2.1+.

Getting the source

git clone https://source.puri.sm/Librem5/feedbackd
cd feedbackd

The master branch has the current development version.

Dependencies

On a Debian based system run

sudo apt-get -y install build-essential
sudo apt-get -y build-dep .

For an explicit list of dependencies check the Build-Depends entry in the debian/control file.

Building

We use the meson (and thereby Ninja) build system for feedbackd. The quickest way to get going is to do the following:

meson . _build
ninja -C _build
ninja -C _build test
ninja -C _build install

Running

Running from the source tree

To run the daemon use

_build/run _build/src/feedbackd

To run under gdb use

FBD_GDB=1 _build/run _build/src/feedbackd

You can introspect and get the current theme with

gdbus introspect --session --dest org.sigxcpu.Feedback --object-path /org/sigxcpu/Feedback

To run feedback for an event, use fbcli

See examples/ for a simple python example using GObject introspection.

How it works

We're using a event naming spec similar to http://0pointer.de/public/sound-naming-spec.html to name events. This will allow us to act as a system sound library so applications only need to call into this library and things like the quiet and silent profile work out of the box.

Any feedback triggered by a client via an event will be stopped latest when the client disconnects from DBus. This makes sure all feedbacks get canceled if the app that triggered it crashes.

Feedback theme

Events are then mapped to a specific type of feedback (sound, led, vibra) via a device specific theme - since devices have different capabilities and different users different needs.

Feedbackd is shipped with a default theme default.json. You can add your own themes in multiple ways:

1. By exporting an environment variable FEEDBACK_THEME with a path to a valid theme file (not recommended, use for testing only), or

2. By creating a theme file under $XDG_CONFIG_HOME/feedbackd/themes/default.json. If XDG_CONFIG_HOME environment variable is not set or empty, it will default to $HOME/.config, or

3. By creating a theme file under $XDG_CONFIG_HOME/feedbackd/themes/custom.json. You only specify the values you want to change in that theme and add an entry

   {
      "name: "custom"
      "parent-theme": "default"
      "profiles" : [
       ...(entries you want to change go here)...
       ]
   }

   next to the name entry in. This has the upside that your theme gets way smaller and that new entries added to the default theme will automatically be used by your theme too. See here for an example. Once you have the file in place, tell feedbackd the them you want to use:

    gsettings set org.sigxcpu.feedbackd theme custom
   

   When you want to go back to the default theme just do:

    gsettings reset org.sigxcpu.feedbackd theme
   

   Note that you can name your theme as you wish but avoid theme names starting with __ or $ as this namespace is reserved. This is the preferred way to specify a custom theme.

4. By adding your theme file to one of the folders in the XDG_DATA_DIRS environment variable, appended with feedbackd/themes/. This folder isn't created automatically, so you have to create it yourself. Here's an example:

   # Check which folders are "valid"
   $ echo $XDG_DATA_DIRS
   [ ... ]:/usr/local/share:/usr/share
   
   # Pick a folder that suits you. Note that you shouldn't place themes in
   # /usr/share, because they would be overwritten by updates!
   # Create missing directories
   $ sudo mkdir -p /usr/local/share/feedbackd/themes
   
   # Add your theme file!
   $ sudo cp my_awesome_theme.json /usr/local/share/feedbackd/themes/

Upon reception of SIGHUP signal, the daemon process will proceed to retrigger the above logic to find the themes, and reload the corresponding one. This can be used to avoid having to restart the daemon in case of configuration changes.

Check out the companion feedbackd-device-themes repository for a selection of device-specific themes. In order for your theme to be recognized it must be named properly. Currently, theme names are based on the compatible device-tree attribute. You can run the following command to get a list of valid filenames for your custom theme (Note: You must run this command on the device you want to create the theme for!):

$ cat /sys/firmware/devicetree/base/compatible | tr '\0' "\n"

Example output (for a Pine64 PinePhone):

$ cat /sys/firmware/devicetree/base/compatible | tr '\0' "\n"
pine64,pinephone-1.2
pine64,pinephone
allwinner,sun50i-a64

Thus you could create a custom feedbackd theme for the Pinephone by placing a modified theme file in /usr/local/share/feedbackd/themes/pine64,pinephone.json

If multiple theme files exist, the selection logic follows these steps:

1. It picks an identifier from the devicetree, until none are left
2. It searches through the folders in XDG_DATA_DIRS in order of appearence, until none are left
3. If a theme file is found in the current location with the current name, it will be chosen and other themes are ignored.

If no theme file can be found this way (i.e. there are no identifiers and folders left to check), default.json is chosen instead. Given the above examples:

• /usr/local/share/feedbackd/themes/pine64,pinephone-1.2.json takes precedence over /usr/local/share/feedbackd/themes/pine64-pinephone.json
• /usr/local/share/feedbackd/themes/pine64-pinephone.json takes precedence over /usr/share/feedbackd/themes/pine64-pinephone-1.2.json
• etc...

For available feeddback types see the feedback-themes(5) manpage.

You can check the feedback theme and the classes (prefixed with Fbd) for available properties. Note that the feedback theme API (including the theme file format) is not stable but considered internal to the daemon.

Profiles

The profile determines which parts of the theme are in use:

• full: Use configured events from the full, quiet and silent parts of the feedback them.
• quiet: Use quiet and silent part from of the feedback theme. This usually means no audio feedback.
• silent: Only use the silent part from the feedback theme. This usually means to not use audio or vibra.

It can be set via a GSetting

  gsettings set org.sigxcpu.feedbackd profile full

fbcli

fbcli can be used to trigger feedback for different events. Here are some examples:

Phone call

Run feedbacks for event phone-incoming-call until explicitly stopped:

_build/cli/fbcli -t 0 -E phone-incoming-call

New instant message

Run feedbacks for event message-new-instant just once:

_build/cli/fbcli -t -1 -E message-new-instant

Alarm clock

Run feedbacks for event message-new-instant for 10 seconds:

_build/cli/fbcli -t 10 -E alarm-clock-elapsed

Examples

Here's some examples that show how to use libfeedback in your application:

C

The command line tool fbcli can be used as example on how to use libfeedback from C.

Python

There's an example.py script demonstrating how to use the introspection bindings and how to trigger feedback via an event.

Rust

The libfeedback-rs Rust bindings ship an example to demo the usage.

Per app profiles

One can set the feedback profile of an individual application via GSettings. E.g. for an app with app id sm.puri.Phosh to set the profile to quiet do:

GSETTINGS_SCHEMA_DIR=_build/data/ gsettings set org.sigxcpu.feedbackd.application:/org/sigxcpu/feedbackd/application/sm-puri-phosh/ profile quiet

Documentation

• Libfeedback API
• Event naming spec draft
• Feedback-theme-spec draft