content/public/browser/speech_recognition_manager.h

// 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.

#ifndef CONTENT_PUBLIC_BROWSER_SPEECH_RECOGNITION_MANAGER_H_
#define CONTENT_PUBLIC_BROWSER_SPEECH_RECOGNITION_MANAGER_H_

#include "base/string16.h"
#include "base/callback.h"
#include "content/common/content_export.h"
#include "content/public/common/speech_recognition_result.h"

namespace content {

class SpeechRecognitionEventListener;
struct SpeechRecognitionSessionConfig;
struct SpeechRecognitionSessionContext;

// The SpeechRecognitionManager (SRM) is a singleton class that handles SR
// functionalities within Chrome. Everyone that needs to perform SR should
// interface exclusively with the SRM, receiving events through the callback
// interface SpeechRecognitionEventListener.
// Since many different sources can use SR in different times (some overlapping
// is allowed while waiting for results), the SRM has the further responsibility
// of handling separately and reliably (taking into account also call sequences
// that might not make sense, e.g., two subsequent AbortSession calls).
// In this sense a session, within the SRM, models the ongoing evolution of a
// SR request from the viewpoint of the end-user, abstracting all the concrete
// operations that must be carried out, that will be handled by inner classes.
class SpeechRecognitionManager {
 public:
  enum { kSessionIDInvalid = 0 };

  // Returns the singleton instance.
  static CONTENT_EXPORT SpeechRecognitionManager* GetInstance();

  // Creates a new recognition session.
  virtual int CreateSession(const SpeechRecognitionSessionConfig& config) = 0;

  // Starts/restarts recognition for an existing session, after performing a
  // premilinary check on the delegate (CheckRecognitionIsAllowed).
  virtual void StartSession(int session_id) = 0;

  // Aborts recognition for an existing session, without providing any result.
  virtual void AbortSession(int session_id) = 0;

  // Aborts all sessions for a given listener, without providing any result.
  virtual void AbortAllSessionsForListener(
      SpeechRecognitionEventListener* listener) = 0;

  // Aborts all sessions for a given RenderView, without providing any result.
  virtual void AbortAllSessionsForRenderView(int render_process_id,
                                             int render_view_id) = 0;

  // Stops audio capture for an existing session. The audio captured before the
  // call will be processed, possibly ending up with a result.
  virtual void StopAudioCaptureForSession(int session_id) = 0;

  // Retrieves the configuration of a session, as provided by the caller
  // upon CreateSession.
  virtual const SpeechRecognitionSessionConfig& GetSessionConfig(int session_id)
      const = 0;

  // Retrieves the context associated to a session.
  virtual SpeechRecognitionSessionContext GetSessionContext(
      int session_id) const = 0;

  // Looks-up an existing session from the context tuple
  // {render_view_id, render_view_id, request_id}.
  virtual int GetSession(int render_process_id,
                         int render_view_id,
                         int request_id) const = 0;

  // Returns true if the OS reports existence of audio recording devices.
  virtual bool HasAudioInputDevices() = 0;

  // Used to determine if something else is currently making use of audio input.
  virtual bool IsCapturingAudio() = 0;

  // Returns a human readable string for the model/make of the active audio
  // input device for this computer.
  virtual string16 GetAudioInputDeviceModel() = 0;

  // Invokes the platform provided microphone settings UI in a non-blocking way,
  // via the BrowserThread::FILE thread.
  virtual void ShowAudioInputSettings() = 0;

 protected:
   virtual ~SpeechRecognitionManager() {}
};

}  // namespace content

#endif  // CONTENT_PUBLIC_BROWSER_SPEECH_RECOGNITION_MANAGER_H_