chrome/browser/speech/tts_platform.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_BROWSER_SPEECH_TTS_PLATFORM_H_
   6 #define CHROME_BROWSER_SPEECH_TTS_PLATFORM_H_
   7
   8 #include <string>
   9
  10 #include "chrome/browser/speech/tts_controller.h"
  11
  12 // Abstract class that defines the native platform TTS interface,
  13 // subclassed by specific implementations on Win, Mac, etc.
  14 class TtsPlatformImpl {
  15  public:
  16   static TtsPlatformImpl* GetInstance();
  17
  18   // Returns true if this platform implementation is supported and available.
  19   virtual bool PlatformImplAvailable() = 0;
  20
  21   // Some platforms may provide a built-in TTS extension. Returns true
  22   // if the extension was not previously loaded and is now loading, and
  23   // false if it's already loaded or if there's no extension to load.
  24   // Will call TtsController::RetrySpeakingQueuedUtterances when
  25   // the extension finishes loading.
  26   virtual bool LoadBuiltInTtsExtension(Profile* profile);
  27
  28   // Speak the given utterance with the given parameters if possible,
  29   // and return true on success. Utterance will always be nonempty.
  30   // If rate, pitch, or volume are -1.0, they will be ignored.
  31   //
  32   // The TtsController will only try to speak one utterance at
  33   // a time. If it wants to interrupt speech, it will always call Stop
  34   // before speaking again.
  35   virtual bool Speak(
  36       int utterance_id,
  37       const std::string& utterance,
  38       const std::string& lang,
  39       const VoiceData& voice,
  40       const UtteranceContinuousParameters& params) = 0;
  41
  42   // Stop speaking immediately and return true on success.
  43   virtual bool StopSpeaking() = 0;
  44
  45   // Returns whether any speech is on going.
  46   virtual bool IsSpeaking() = 0;
  47
  48   // Append information about voices provided by this platform implementation
  49   // to |out_voices|.
  50   virtual void GetVoices(std::vector<VoiceData>* out_voices) = 0;
  51
  52   // Pause the current utterance, if any, until a call to Resume,
  53   // Speak, or StopSpeaking.
  54   virtual void Pause() = 0;
  55
  56   // Resume speaking the current utterance, if it was paused.
  57   virtual void Resume() = 0;
  58
  59   // Allows the platform to monitor speech commands and the voices used
  60   // for each one.
  61   virtual void WillSpeakUtteranceWithVoice(const Utterance* utterance,
  62                                            const VoiceData& voice_data);
  63
  64   virtual std::string error();
  65   virtual void clear_error();
  66   virtual void set_error(const std::string& error);
  67
  68  protected:
  69   TtsPlatformImpl() {}
  70
  71   // On some platforms this may be a leaky singleton - do not rely on the
  72   // destructor being called!  http://crbug.com/122026
  73   virtual ~TtsPlatformImpl() {}
  74
  75   std::string error_;
  76
  77   DISALLOW_COPY_AND_ASSIGN(TtsPlatformImpl);
  78 };
  79
  80 #endif  // CHROME_BROWSER_SPEECH_TTS_PLATFORM_H_