Prism is the Platform-agnostic Reader Interface for Speech and Messages. Since that's a hell of a mouthful, we just call it Prism for short. The name comes from prisms in optics, which are transparent optical components with flat surfaces that refract light into many beams. Thus, the metaphor: refract your TTS strings to send them to many different backends, potentially simultaneously.
Prism aims to unify the various screen reader abstraction libraries like SpeechCore, UniversalSpeech, SRAL, Tolk, etc., into a single unified system with a single unified API. Of course, we also support traditional TTS engines. I have tried to develop Prism in such a way that compilation is trivial and requires no external dependencies. To that end, the CMake builder will download all needed dependencies. However, since it uses cpm.cmake, vendoring of dependencies is very possible.
To build Prism, all you need do is create a build directory and run cmake as you ordinarily would. The following build options are available:
| Option | Description |
|---|---|
PRISM_ENABLE_TESTS |
Build the test suite (currently reserved). |
PRISM_ENABLE_DEMOS |
Enable building of demo apps to demonstrate Prism either generally or being used in a specific language. |
PRISM_ENABLE_LINTING |
Enable linting of source code with clang-tidy and other static analysis tools. |
PRISM_ENABLE_VCPKG_SPECIFIC_OPTIONS |
DO NOT USE. Enables options primarily used by the vcpkg package manager. |
Prism is also in vcpkg. To install it:
vcpkg install ethindp-prism
The following features are available:
| Feature | Description |
|---|---|
speech-dispatcher |
Enables linking to speech dispatcher and, by extension, enables the respective back-end module. If not defined, speech dispatcher will NOT be a supported backend. |
orca |
Enables use of glib and gdbus to communicate directly with the Orca screen reader. If not defined, Orca will NOT be available as a supported backend. |
Documentation uses mdbook. To view it offline, install mdbook and then run mdbook serve from the doc directory.
The API is fully documented in the documentation above. If the documentation and header do not align in guarantees or expectations, this is a bug and should be reported.
Currently bindings are an in-progress effort. The following Bindings exist:
| Language | Package/add-on/etc. |
|---|---|
| .NET | prismatoid |
| Python | Prismatoid |
We welcome future bindings. If you write bindings and want them added here, please submit a PR!
This project is licensed under the Mozilla Public License version 2.0. Full details are available in the LICENSE file.
This project uses code from other projects. Specifically:
- The SAPI bridge is credited to the NVGT project, as well as the functions
range_convertandrange_convert_midpointin utils.h and utils.cpp. Similar attribution goes to NVGT for the Android screen reader backend. - The
simdutflibrary is licensed under the Apache-2.0 license. - On Windows, Prism includes NVDA controller client RPC definitions originally under LGPL-2.1 (and generated RPC stubs from those inputs). The Prism project has received permission to license the IDL files (and there generated outputs) under the MPL-2.0 regardless of the original license. Thus, you may assume that they are licensed under the MPL-2.0. The LGPL headers and license file in the LICENSES directory remain for providing attribution.
Contributions are welcome. This includes, but is not limited to, documentation enhancements, new backends, bindings, build system improvements, etc. The project uses C++23 so please ensure that your compiler supports that standard.
