chromium/src/third_party/blink/public/mojom/speech/speech_synthesis.mojom

// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

module blink.mojom;

const double kSpeechSynthesisDefaultRate = 1.0;
const double kSpeechSynthesisDefaultPitch = 1.0;
const double kSpeechSynthesisDefaultVolume = 1.0;
const double kSpeechSynthesisDoublePrefNotSet = -1.0;

struct SpeechSynthesisUtterance {
  string text;
  string lang;
  string voice;
  double volume;
  double rate;
  double pitch;
};

struct SpeechSynthesisVoice {
  string voice_uri;
  string name;
  string lang;
  bool is_local_service;
  bool is_default;
};

// This interface receives updates to the list of voices. See SpeechSynthesis'
// AddVoiceListObserver method.
interface SpeechSynthesisVoiceListObserver {
  // Receives the list of voices that may be used.
  OnSetVoiceList(array<SpeechSynthesisVoice> voice_list);
};

// This interface receives events related to speaking a particular utterance.
// See SpeechSynthesis' Speak method.
interface SpeechSynthesisClient {
  // The utterance started.
  OnStartedSpeaking();

  // The utterance finished, and no further events will be received.
  OnFinishedSpeaking();

  // The utterance was paused.
  OnPausedSpeaking();

  // The utterance was resumed.
  OnResumedSpeaking();

  // A word boundary was encountered while speaking the utterance.
  OnEncounteredWordBoundary(uint32 char_index, uint32 char_length);

  // A sentence boundary was encountered while speaking the utterance.
  OnEncounteredSentenceBoundary(uint32 char_index, uint32 char_length);

  // An error occurred while speaking the utterance, and no further events will
  // be received.
  OnEncounteredSpeakingError();
};

// This interface is used to forward speech synthesis requests to a text-to-
// speech engine. Call the Speak method to request an utterance to be spoken.
interface SpeechSynthesis {
  // Observers are notified once upon being added, to receive the current voice
  // list. They are notified again whenever the voice list changes.
  AddVoiceListObserver(pending_remote<SpeechSynthesisVoiceListObserver> observer);

  // Begin speaking the given utterance. Events will be delivered to the client.
  Speak(SpeechSynthesisUtterance utterance,
        pending_remote<SpeechSynthesisClient> client);

  // Pause speaking all utterances.
  Pause();

  // Resume speaking all utterances.
  Resume();

  // Cancel speaking all utterances.
  Cancel();
};