Orca is a free, open source, flexible, and extensible screen reader that provides access to the graphical desktop via user-customizable combinations of speech and/or braille.

Orca works with applications and toolkits that support the assistive technology service provider interface (AT-SPI), which is the primary assistive technology infrastructure for the Solaris and Linux operating environments. Applications and toolkits supporting the AT-SPI include the GNOME GTK+ toolkit, the Java platform's Swing toolkit, OpenOffice/LibreOffice, Gecko, and WebKitGtk. AT-SPI support for the KDE Qt toolkit is currently being pursued.

See also http://wiki.gnome.org/Projects/Orca for detailed English and Spanish information on Orca, including how to run Orca, how to communicate with the Orca user community, and where to log bugs and feature requests.

Orca v40.x is supported on GNOME 40.x only. We highly suggest you use the latest releases of GNOME because they contain accessibility infrastructure and application bug fixes that help Orca work better.

Orca also has the following dependencies:

• Python 3 - Python platform
• pygobject-3.0 - Python bindings for the GObject library
• gtk+-3.0 - GTK+ toolkit
• json-py - a JSON (https://json.org/) reader and writer in Python
• python-speechd - Python bindings for Speech Dispatcher (optional)
• BrlTTY - BrlTTY (https://mielke.cc/brltty/) support for braille (optional)
• BrlAPI - BrlAPI support for braille (optional)
• liblouis - Liblouis (http://liblouis.org/) support for contracted braille (optional)
• py-setproctitle - Python library to set the process title (optional)
• gstreamer-1.0 - GStreamer - Streaming media framework (optional)

You are strongly encouraged to also have the latest stable versions of AT-SPI2 and ATK for the GNOME 40.x release.

Orca depends upon the Python bindings for BrlAPI available in BrlTTY v4.5 or better. You can determine if the Python bindings for BrlAPI are installed by running the following command:

python -c "import brlapi"

If you get an error, the Python bindings for BrlAPI are not installed.

If you wish to modify your Orca preferences, you can press "Insert+space" while Orca is running.

To get help while running Orca, press "Insert+H". This will enable "learn mode", which provides a spoken and brailled description of what various keyboard and braille input device actions will do. To exit learn mode, press "Escape." Finally, the preferences dialog contains a "Key Bindings" tab that lists the keyboard binding for Orca.

For more information, see the Orca documentation which is available within Orca as well as at: https://help.gnome.org/users/orca/stable/

So, you want to write a script for Orca? The best thing to do is start by looking at other scripts under the src/orca/scripts/ hierarchy of the source tree.