Crate prism_sys 

Raw FFI bindings to prism (https://github.com/ethindp/prism), a platform-agnostic speech and screen reader output library.

Structs

PrismBackend

An opaque backend instance obtained from a registry.

PrismBackendVTable

A table of function pointers implementing a custom backend.

PrismConfig

A struct containing configuration parameters for Prism or it’s back-ends to use.

PrismContext

An opaque prism context, holding a backend registry.

PrismLogHandler

A structure pairing a log callback with an opaque user pointer.

PrismPluginBackend

A descriptor supplied by a plugin to describe a single backend.

PrismPluginHost

A structure describing the loading Prism library, passed to a plugin’s entry point.

PrismPluginInstanceContext

The structure Prism passes as the userdata argument to the create member of a backend supplied by a plugin. The context is valid only for the duration of the create call; the services object it names is valid for the longer period given under Host services.

PrismPluginServices

A structure through which a backend supplied by a plugin reaches the facilities Prism makes available to it. Prism provides one to each backend it registers from a plugin, as described under Host services.

PrismRegistry

An opaque, immutable set of backend registrations.

PrismRegistryBuilder

An opaque, mutable collection of backend registrations.

Constants

PRISM_BACKEND_ANDROID_SCREEN_READER

Android screen readers (Android)

PRISM_BACKEND_ANDROID_TTS

Android TTS engine (Android)

PRISM_BACKEND_AV_SPEECH

AVSpeechSynthesizer (macOS, iOS, tvOS, WatchOS, VisionOS)

PRISM_BACKEND_BOY_PC_READER

BoyPCReader (windows only)

PRISM_BACKEND_FEATURE_MAX_BIT

The highest bit reserved for feature flags.

PRISM_BACKEND_INVALID

Invalid/sentinel value (always 0)

PRISM_BACKEND_IS_SUPPORTED_AT_RUNTIME

The underlying engine or service is available. This determination is advisory; prism_backend_initialize MAY still fail.

PRISM_BACKEND_JAWS

JAWS screen reader (Windows)

PRISM_BACKEND_NVDA

NVDA screen reader (Windows)

PRISM_BACKEND_ONE_CORE

Windows OneCore speech API (Windows 10+)

PRISM_BACKEND_ORCA

Orca screen reader (Linux/BSD, win32 via Wine)

PRISM_BACKEND_PC_TALKER

PCTalker (windows only)

PRISM_BACKEND_PERFORMS_SILENCE_TRIMMING_ON_SPEAK

Reserved.

PRISM_BACKEND_PERFORMS_SILENCE_TRIMMING_ON_SPEAK_TO_MEMORY

The backend trims leading and trailing silence from the audio stream before delivering it to the audio callback.

PRISM_BACKEND_SAPI

Microsoft SAPI (Windows)

PRISM_BACKEND_SENSE_READER

Sense Reader screen reader (Windows)

PRISM_BACKEND_SPEECH_DISPATCHER

Speech Dispatcher (Linux/BSD, win32 via Wine)

PRISM_BACKEND_SPIEL

Spiel (Linux and BSDs only)

PRISM_BACKEND_SUPPORTS_BRAILLE

prism_backend_braille is implemented.

PRISM_BACKEND_SUPPORTS_COUNT_VOICES

prism_backend_count_voices is implemented.

PRISM_BACKEND_SUPPORTS_GET_BIT_DEPTH

prism_backend_get_bit_depth is implemented.

PRISM_BACKEND_SUPPORTS_GET_CHANNELS

prism_backend_get_channels is implemented.

PRISM_BACKEND_SUPPORTS_GET_PITCH

prism_backend_get_pitch is implemented.

PRISM_BACKEND_SUPPORTS_GET_RATE

prism_backend_get_rate is implemented.

PRISM_BACKEND_SUPPORTS_GET_SAMPLE_RATE

prism_backend_get_sample_rate is implemented.

PRISM_BACKEND_SUPPORTS_GET_VOICE

prism_backend_get_voice is implemented.

PRISM_BACKEND_SUPPORTS_GET_VOICE_LANGUAGE

prism_backend_get_voice_language is implemented.

PRISM_BACKEND_SUPPORTS_GET_VOICE_NAME

prism_backend_get_voice_name is implemented.

PRISM_BACKEND_SUPPORTS_GET_VOLUME

prism_backend_get_volume is implemented.

PRISM_BACKEND_SUPPORTS_IS_SPEAKING

prism_backend_is_speaking is implemented.

PRISM_BACKEND_SUPPORTS_OUTPUT

prism_backend_output is implemented.

PRISM_BACKEND_SUPPORTS_PAUSE

prism_backend_pause is implemented.

PRISM_BACKEND_SUPPORTS_REFRESH_VOICES

prism_backend_refresh_voices is implemented.

PRISM_BACKEND_SUPPORTS_RESUME

prism_backend_resume is implemented.

PRISM_BACKEND_SUPPORTS_SET_PITCH

prism_backend_set_pitch is implemented.

PRISM_BACKEND_SUPPORTS_SET_RATE

prism_backend_set_rate is implemented.

PRISM_BACKEND_SUPPORTS_SET_VOICE

prism_backend_set_voice is implemented.

PRISM_BACKEND_SUPPORTS_SET_VOLUME

prism_backend_set_volume is implemented.

PRISM_BACKEND_SUPPORTS_SPEAK

prism_backend_speak is implemented.

PRISM_BACKEND_SUPPORTS_SPEAK_SSML

Reserved.

PRISM_BACKEND_SUPPORTS_SPEAK_TO_MEMORY

prism_backend_speak_to_memory is implemented.

PRISM_BACKEND_SUPPORTS_SPEAK_TO_MEMORY_SSML

Reserved.

PRISM_BACKEND_SUPPORTS_STOP

prism_backend_stop is implemented.

PRISM_BACKEND_SYSTEM_ACCESS

SystemAccess screen reader (windows) (only available if explicitly enabled at build time)

PRISM_BACKEND_UIA

UIAutomation backend (Windows only)

PRISM_BACKEND_VOICE_OVER

VoiceOver screen reader (macOS, MacCatalyst, iOS, WatchOS, tvOS, VisionOS)

PRISM_BACKEND_WEB_SPEECH

Web SpeechSynthesis API (web)

PRISM_BACKEND_WINDOW_EYES

WindowEyes screen reader (windows) (only available if explicitly enabled at build time)

PRISM_BACKEND_ZDSR

Zhengdu Screen Reader (Windows)

PRISM_BACKEND_ZOOM_TEXT

ZoomText (Windows)

PRISM_CONFIG_VERSION

The PrismConfig layout version this binding describes.

PRISM_ERROR_ALREADY_INITIALIZED

The backend was already initialized.

PRISM_ERROR_ALREADY_PAUSED

Speech is already paused.

PRISM_ERROR_BACKEND_ENTERED_UNDEFINED_STATE

An error occured when the backend was executing a function which has caused the backend to enter an undefined state. The caller should re-initialize the backend from scratch.

PRISM_ERROR_BACKEND_NOT_AVAILABLE

The backend’s underlying system component is unavailable.

PRISM_ERROR_COUNT

The number of defined error codes. Not itself an error.

PRISM_ERROR_INCOMPATIBLE_ABI

A plugin declined the host, or a backend descriptor declared an ABI generation this build of Prism does not accept

PRISM_ERROR_INTERNAL

An internal error occurred during initialization.

PRISM_ERROR_INTERNAL_BACKEND_LIMIT_EXCEEDED

The backend possesses an internal hard ceiling as to how many instances may be instantiated at any given time, and this limit would be exceeded were another to be initialized.

PRISM_ERROR_INVALID_AUDIO_FORMAT

The audio format which the underlying engine returned to Prism cannot be understood by Prism, or it’s parameters are nonsensical.

PRISM_ERROR_INVALID_OPERATION

The builder is spent, or a backend with the same name or the same identifier is already present in the builder.

PRISM_ERROR_INVALID_PARAM

The vtable’s size member was zero, the declared feature set was inconsistent with the vtable, or the priority value was negative.

PRISM_ERROR_INVALID_UTF8

text contains invalid UTF-8 sequences.

PRISM_ERROR_LIBRARY_INVALID

A shared library was opened but does not export the plugin entry point

PRISM_ERROR_LIBRARY_LOAD_FAILED

A shared library could not be opened, because no file exists at the given path, it is not a loadable image, it was built for a different architecture, or its initialization code failed

PRISM_ERROR_MEMORY_FAILURE

Memory allocation failed during initialization.

PRISM_ERROR_NOT_IMPLEMENTED

The backend does not support audio format queries.

PRISM_ERROR_NOT_INITIALIZED

The backend has not been initialized.

PRISM_ERROR_NOT_PAUSED

Speech is not currently paused.

PRISM_ERROR_NOT_SPEAKING

No speech is currently playing.

PRISM_ERROR_NO_VOICES

No voices are available for this backend

PRISM_ERROR_RANGE_OUT_OF_BOUNDS

A parameter value exceeded its valid range

PRISM_ERROR_SPEAK_FAILURE

Speech synthesis failed.

PRISM_ERROR_UNKNOWN

An unspecified error occurred.

PRISM_ERROR_VOICE_NOT_FOUND

The specified voice was not found

PRISM_LOG_LEVEL_DEBUG

Diagnostic information useful during development.

PRISM_LOG_LEVEL_ERROR

Error conditions.

PRISM_LOG_LEVEL_INFO

Informational messages describing normal operation.

PRISM_LOG_LEVEL_NONE

Not a message severity. When supplied to prism_set_log_level, it suppresses all messages, since no message has a severity greater than or equal to it.

PRISM_LOG_LEVEL_TRACE

The most verbose level, used for fine-grained tracing of internal operations.

PRISM_LOG_LEVEL_WARN

Conditions that are not errors but MAY indicate a problem.

PRISM_OK

Channel count was retrieved.

PRISM_PLUGIN_ABI_VERSION

The plugin ABI generation this binding describes.

Functions

prism_availability_auto_power_supported^⚠

Reports whether this build can pause and resume polling automatically in response to operating-system power transitions.

prism_availability_poll_pause^⚠

Pauses the availability poll thread.

prism_availability_poll_resume^⚠

Resumes the availability poll thread.

prism_backend_braille^⚠

Outputs text to a connected braille display.

prism_backend_count_voices^⚠

Returns the number of voices available from the backend.

prism_backend_free^⚠

Releases a backend instance.

prism_backend_get_bit_depth^⚠

Retrieves the native bit depth of audio produced by the backend.

prism_backend_get_channels^⚠

Retrieves the number of audio channels produced by the backend.

prism_backend_get_features^⚠

Returns a bitmask of all features supported by this backend, as well as other information.

prism_backend_get_pitch^⚠

Retrieves the current speech pitch.

prism_backend_get_rate^⚠

Retrieves the current speech rate.

prism_backend_get_sample_rate^⚠

Retrieves the sample rate of audio produced by the backend.

prism_backend_get_voice^⚠

Retrieves the index of the currently selected voice.

prism_backend_get_voice_language^⚠

Retrieves the language code or language string of a voice.

prism_backend_get_voice_name^⚠

Retrieves the human-readable name of a voice.

prism_backend_get_volume^⚠

Retrieves the current speech volume.

prism_backend_initialize^⚠

Initializes a backend instance.

prism_backend_is_speaking^⚠

Queries whether the backend is currently producing speech output.

prism_backend_name^⚠

Returns the human-readable name of a backend.

prism_backend_output^⚠

Outputs text using all available modalities supported by the backend.

prism_backend_pause^⚠

Pauses currently playing speech.

prism_backend_refresh_voices^⚠

Refreshes the backend’s internal voice list.

prism_backend_resume^⚠

Resumes previously paused speech.

prism_backend_set_pitch^⚠

Sets the speech pitch.

prism_backend_set_rate^⚠

Sets the speech rate (speed).

prism_backend_set_voice^⚠

Selects a voice to use for subsequent speech synthesis.

prism_backend_set_volume^⚠

Sets the speech volume.

prism_backend_speak^⚠

Synthesizes speech from the given text and plays it through the default audio output.

prism_backend_speak_to_memory^⚠

Synthesizes speech from the given text and delivers the audio samples to a callback function.

prism_backend_stop^⚠

Immediately stops any currently playing speech.

prism_config_init^⚠

Creates a new configuration structure which can be passed to prism_init.

prism_error_string^⚠

Returns a human-readable description of an error code.

prism_init^⚠

Creates a new Prism context.

prism_log^⚠

Emits a log message.

prism_log_flush^⚠

Blocks until all messages queued before the call have been delivered.

prism_log_shutdown^⚠

Stops the logging thread and releases the resources associated with the logger.

prism_registry_acquire^⚠

Acquires a backend instance, reusing a cached instance if available or creating a new one otherwise.

prism_registry_acquire_best^⚠

Acquires the highest-priority backend that successfully initializes, reusing a cached instance if available.

prism_registry_builder_add_backend^⚠

Adds a custom backend to a registry builder.

prism_registry_builder_add_library^⚠

Loads a plugin from a shared library and adds each backend it supplies to a registry builder.

prism_registry_builder_free^⚠

Releases a registry builder.

prism_registry_builder_new^⚠

Creates a new registry builder seeded with the compiled-in backends.

prism_registry_count^⚠

Returns the number of backends registered in the registry.

prism_registry_create^⚠

Creates a new backend instance.

prism_registry_create_best^⚠

Creates a new instance of the highest-priority backend that successfully initializes.

prism_registry_exists^⚠

Checks whether a backend with the given ID exists in the registry.

prism_registry_freeze^⚠

Freezes a builder, producing an immutable registry.

prism_registry_get^⚠

Retrieves a cached backend instance if one exists.

prism_registry_id^⚠

Looks up a backend by name and returns its ID.

prism_registry_id_at^⚠

Returns the backend ID at the specified index in the registry.

prism_registry_name^⚠

Returns the human-readable name of a backend given its ID.

prism_registry_priority^⚠

Returns the priority value of a backend.

prism_registry_release^⚠

Decrements the reference count of a registry, finalizing it when the count reaches zero.

prism_registry_retain^⚠

Increments the reference count of a registry.

prism_set_log_handler^⚠

Installs the handler that receives log messages, replacing any previously installed handler.

prism_set_log_level^⚠

Sets the minimum severity of messages that will be delivered.

prism_shutdown^⚠

Destroys a Prism context and releases associated resources.

prism_version^⚠

Returns the version of the loaded Prism library as an encoded integer.

prism_version_string^⚠

Returns the version of the loaded Prism library as a human-readable string.

Type Aliases

PrismAudioCallback

Receives audio samples from prism_backend_speak_to_memory.

PrismAvailabilityBaselineCallback

The type of a function invoked once the poll thread has established its availability baseline.

PrismAvailabilityCallback

The type of a function invoked when a backend’s runtime availability changes.

PrismBackendId

A backend’s identifier, derived from its name.

PrismError

An error code. PRISM_OK means success; every other value is a failure.

PrismLogCallback

The type of a function invoked to deliver a single log message.

PrismLogLevel

The severity of a log message, or a threshold for delivering them.

PrismPluginQueryFn

The entry point a prism plugin shared library exports.