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// Copyright (c) 2012 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.
#include <memory>
#include <queue>
#include <set>
#include <string>
#include <vector>
#include "base/memory/singleton.h"
#include "base/memory/weak_ptr.h"
#include "url/gurl.h"
class Utterance;
class TtsPlatformImpl;
namespace base {
class Value;
namespace content {
class BrowserContext;
// Events sent back from the TTS engine indicating the progress.
enum TtsEventType {
enum TtsGenderType {
// Returns true if this event type is one that indicates an utterance
// is finished and can be destroyed.
bool IsFinalTtsEventType(TtsEventType event_type);
// The continuous parameters that apply to a given utterance.
struct UtteranceContinuousParameters {
double rate;
double pitch;
double volume;
// Information about one voice.
struct VoiceData {
VoiceData(const VoiceData& other);
std::string name;
std::string lang;
TtsGenderType gender;
std::string extension_id;
std::set<TtsEventType> events;
// If true, the synthesis engine is a remote network resource.
// It may be higher latency and may incur bandwidth costs.
bool remote;
// If true, this is implemented by this platform's subclass of
// TtsPlatformImpl. If false, this is implemented by an extension.
bool native;
std::string native_voice_identifier;
// Interface that delegates TTS requests to user-installed extensions.
class TtsEngineDelegate {
virtual ~TtsEngineDelegate() {}
// Return a list of all available voices registered.
virtual void GetVoices(content::BrowserContext* browser_context,
std::vector<VoiceData>* out_voices) = 0;
// Speak the given utterance by sending an event to the given TTS engine.
virtual void Speak(Utterance* utterance, const VoiceData& voice) = 0;
// Stop speaking the given utterance by sending an event to the target
// associated with this utterance.
virtual void Stop(Utterance* utterance) = 0;
// Pause in the middle of speaking this utterance.
virtual void Pause(Utterance* utterance) = 0;
// Resume speaking this utterance.
virtual void Resume(Utterance* utterance) = 0;
// Load the built-in component extension for ChromeOS.
virtual bool LoadBuiltInTtsExtension(
content::BrowserContext* browser_context) = 0;
// Class that wants to receive events on utterances.
class UtteranceEventDelegate {
virtual ~UtteranceEventDelegate() {}
virtual void OnTtsEvent(Utterance* utterance,
TtsEventType event_type,
int char_index,
const std::string& error_message) = 0;
// Class that wants to be notified when the set of
// voices has changed.
class VoicesChangedDelegate {
virtual ~VoicesChangedDelegate() {}
virtual void OnVoicesChanged() = 0;
// One speech utterance.
class Utterance {
// Construct an utterance given a profile and a completion task to call
// when the utterance is done speaking. Before speaking this utterance,
// its other parameters like text, rate, pitch, etc. should all be set.
explicit Utterance(content::BrowserContext* browser_context);
// Sends an event to the delegate. If the event type is TTS_EVENT_END
// or TTS_EVENT_ERROR, deletes the utterance. If |char_index| is -1,
// uses the last good value.
void OnTtsEvent(TtsEventType event_type,
int char_index,
const std::string& error_message);
// Finish an utterance without sending an event to the delegate.
void Finish();
// Getters and setters for the text to speak and other speech options.
void set_text(const std::string& text) { text_ = text; }
const std::string& text() const { return text_; }
void set_options(const base::Value* options);
const base::Value* options() const { return options_.get(); }
void set_src_id(int src_id) { src_id_ = src_id; }
int src_id() { return src_id_; }
void set_src_url(const GURL& src_url) { src_url_ = src_url; }
const GURL& src_url() { return src_url_; }
void set_voice_name(const std::string& voice_name) {
voice_name_ = voice_name;
const std::string& voice_name() const { return voice_name_; }
void set_lang(const std::string& lang) {
lang_ = lang;
const std::string& lang() const { return lang_; }
void set_gender(TtsGenderType gender) {
gender_ = gender;
TtsGenderType gender() const { return gender_; }
void set_continuous_parameters(const double rate,
const double pitch,
const double volume) {
continuous_parameters_.rate = rate;
continuous_parameters_.pitch = pitch;
continuous_parameters_.volume = volume;
const UtteranceContinuousParameters& continuous_parameters() {
return continuous_parameters_;
void set_can_enqueue(bool can_enqueue) { can_enqueue_ = can_enqueue; }
bool can_enqueue() const { return can_enqueue_; }
void set_required_event_types(const std::set<TtsEventType>& types) {
required_event_types_ = types;
const std::set<TtsEventType>& required_event_types() const {
return required_event_types_;
void set_desired_event_types(const std::set<TtsEventType>& types) {
desired_event_types_ = types;
const std::set<TtsEventType>& desired_event_types() const {
return desired_event_types_;
const std::string& extension_id() const { return extension_id_; }
void set_extension_id(const std::string& extension_id) {
extension_id_ = extension_id;
UtteranceEventDelegate* event_delegate() const {
return event_delegate_;
void set_event_delegate(UtteranceEventDelegate* event_delegate) {
event_delegate_ = event_delegate;
// Getters and setters for internal state.
content::BrowserContext* browser_context() const { return browser_context_; }
int id() const { return id_; }
bool finished() const { return finished_; }
// The BrowserContext that initiated this utterance.
content::BrowserContext* browser_context_;
// The extension ID of the extension providing TTS for this utterance, or
// empty if native TTS is being used.
std::string extension_id_;
// The unique ID of this utterance, used to associate callback functions
// with utterances.
int id_;
// The id of the next utterance, so we can associate requests with
// responses.
static int next_utterance_id_;
// The text to speak.
std::string text_;
// The full options arg passed to tts.speak, which may include fields
// other than the ones we explicitly parse, below.
std::unique_ptr<base::Value> options_;
// The source extension's ID of this utterance, so that it can associate
// events with the appropriate callback.
int src_id_;
// The URL of the page where the source extension called speak.
GURL src_url_;
// The delegate to be called when an utterance event is fired.
UtteranceEventDelegate* event_delegate_;
// The parsed options.
std::string voice_name_;
std::string lang_;
TtsGenderType gender_;
UtteranceContinuousParameters continuous_parameters_;
bool can_enqueue_;
std::set<TtsEventType> required_event_types_;
std::set<TtsEventType> desired_event_types_;
// The index of the current char being spoken.
int char_index_;
// True if this utterance received an event indicating it's done.
bool finished_;
// Singleton class that manages text-to-speech for the TTS and TTS engine
// extension APIs, maintaining a queue of pending utterances and keeping
// track of all state.
class TtsController {
// Get the single instance of this class.
static TtsController* GetInstance();
// Returns true if we're currently speaking an utterance.
virtual bool IsSpeaking() = 0;
// Speak the given utterance. If the utterance's can_enqueue flag is true
// and another utterance is in progress, adds it to the end of the queue.
// Otherwise, interrupts any current utterance and speaks this one
// immediately.
virtual void SpeakOrEnqueue(Utterance* utterance) = 0;
// Stop all utterances and flush the queue. Implies leaving pause mode
// as well.
virtual void Stop() = 0;
// Pause the speech queue. Some engines may support pausing in the middle
// of an utterance.
virtual void Pause() = 0;
// Resume speaking.
virtual void Resume() = 0;
// Handle events received from the speech engine. Events are forwarded to
// the callback function, and in addition, completion and error events
// trigger finishing the current utterance and starting the next one, if
// any.
virtual void OnTtsEvent(int utterance_id,
TtsEventType event_type,
int char_index,
const std::string& error_message) = 0;
// Return a list of all available voices, including the native voice,
// if supported, and all voices registered by extensions.
virtual void GetVoices(content::BrowserContext* browser_context,
std::vector<VoiceData>* out_voices) = 0;
// Called by the extension system or platform implementation when the
// list of voices may have changed and should be re-queried.
virtual void VoicesChanged() = 0;
// Add a delegate that wants to be notified when the set of voices changes.
virtual void AddVoicesChangedDelegate(VoicesChangedDelegate* delegate) = 0;
// Remove delegate that wants to be notified when the set of voices changes.
virtual void RemoveVoicesChangedDelegate(VoicesChangedDelegate* delegate) = 0;
// Remove delegate that wants to be notified when an utterance fires an event.
// Note: this cancels speech from any utterance with this delegate, and
// removes any utterances with this delegate from the queue.
virtual void RemoveUtteranceEventDelegate(UtteranceEventDelegate* delegate)
= 0;
// Set the delegate that processes TTS requests with user-installed
// extensions.
virtual void SetTtsEngineDelegate(TtsEngineDelegate* delegate) = 0;
// Get the delegate that processes TTS requests with user-installed
// extensions.
virtual TtsEngineDelegate* GetTtsEngineDelegate() = 0;
// For unit testing.
virtual void SetPlatformImpl(TtsPlatformImpl* platform_impl) = 0;
virtual int QueueSize() = 0;
virtual ~TtsController() {}