chrome/renderer/tts_dispatcher.h

// Copyright (c) 2013 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.

#ifndef CHROME_RENDERER_TTS_DISPATCHER_H_
#define CHROME_RENDERER_TTS_DISPATCHER_H_

#include <map>
#include <vector>

#include "base/compiler_specific.h"
#include "base/macros.h"
#include "content/public/renderer/render_thread_observer.h"
#include "third_party/blink/public/platform/web_speech_synthesizer.h"
#include "third_party/blink/public/platform/web_speech_synthesizer_client.h"

namespace IPC {
class Message;
}

struct TtsVoice;

// TtsDispatcher is a delegate for methods used by Blink for speech synthesis
// APIs. It's the complement of TtsDispatcherHost (owned by RenderViewHost).
// Each TtsDispatcher is owned by the WebSpeechSynthesizerClient in Blink;
// it registers itself to listen to IPC upon construction and unregisters
// itself when deleted. There can be multiple TtsDispatchers alive at once,
// so each one routes IPC messages to its WebSpeechSynthesizerClient only if
// the utterance id (which is globally unique) matches.
class TtsDispatcher
    : public blink::WebSpeechSynthesizer,
      public content::RenderThreadObserver {
 public:
  explicit TtsDispatcher(blink::WebSpeechSynthesizerClient* client);
  ~TtsDispatcher() override;

 private:
  // RenderThreadObserver override.
  bool OnControlMessageReceived(const IPC::Message& message) override;

  // blink::WebSpeechSynthesizer implementation.
  void UpdateVoiceList() override;
  void Speak(const blink::WebSpeechSynthesisUtterance& utterance) override;
  void Pause() override;
  void Resume() override;
  void Cancel() override;

  blink::WebSpeechSynthesisUtterance FindUtterance(int utterance_id);

  void OnSetVoiceList(const std::vector<TtsVoice>& voices);
  void OnDidStartSpeaking(int utterance_id);
  void OnDidFinishSpeaking(int utterance_id);
  void OnDidPauseSpeaking(int utterance_id);
  void OnDidResumeSpeaking(int utterance_id);
  void OnWordBoundary(int utterance_id, int char_index);
  void OnSentenceBoundary(int utterance_id, int char_index);
  void OnMarkerEvent(int utterance_id, int char_index);
  void OnWasInterrupted(int utterance_id);
  void OnWasCancelled(int utterance_id);
  void OnSpeakingErrorOccurred(int utterance_id,
                               const std::string& error_message);

  // The WebKit client class that we use to send events back to the JS world.
  // Weak reference, this will be valid as long as this object exists.
  blink::WebSpeechSynthesizerClient* synthesizer_client_;

  // Next utterance id, used to map response IPCs to utterance objects.
  static int next_utterance_id_;

  // Map from id to utterance objects.
  std::map<int, blink::WebSpeechSynthesisUtterance> utterance_id_map_;

  DISALLOW_COPY_AND_ASSIGN(TtsDispatcher);
};

#endif  // CHROME_RENDERER_TTS_DISPATCHER_H_