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(
  27       content::BrowserContext* browser_context);
  28
  29   // Speak the given utterance with the given parameters if possible,
  30   // and return true on success. Utterance will always be nonempty.
  31   // If rate, pitch, or volume are -1.0, they will be ignored.
  32   //
  33   // The TtsController will only try to speak one utterance at
  34   // a time. If it wants to interrupt speech, it will always call Stop
  35   // before speaking again.
  36   virtual bool Speak(
  37       int utterance_id,
  38       const std::string& utterance,
  39       const std::string& lang,
  40       const VoiceData& voice,
  41       const UtteranceContinuousParameters& params) = 0;
  42
  43   // Stop speaking immediately and return true on success.
  44   virtual bool StopSpeaking() = 0;
  45
  46   // Returns whether any speech is on going.
  47   virtual bool IsSpeaking() = 0;
  48
  49   // Append information about voices provided by this platform implementation
  50   // to |out_voices|.
  51   virtual void GetVoices(std::vector<VoiceData>* out_voices) = 0;
  52
  53   // Pause the current utterance, if any, until a call to Resume,
  54   // Speak, or StopSpeaking.
  55   virtual void Pause() = 0;
  56
  57   // Resume speaking the current utterance, if it was paused.
  58   virtual void Resume() = 0;
  59
  60   // Allows the platform to monitor speech commands and the voices used
  61   // for each one.
  62   virtual void WillSpeakUtteranceWithVoice(const Utterance* utterance,
  63                                            const VoiceData& voice_data);
  64
  65   virtual std::string error();
  66   virtual void clear_error();
  67   virtual void set_error(const std::string& error);
  68
  69  protected:
  70   TtsPlatformImpl() {}
  71
  72   // On some platforms this may be a leaky singleton - do not rely on the
  73   // destructor being called!  http://crbug.com/122026
  74   virtual ~TtsPlatformImpl() {}
  75
  76   std::string error_;
  77
  78   DISALLOW_COPY_AND_ASSIGN(TtsPlatformImpl);
  79 };
  80
  81 #endif  // CHROME_BROWSER_SPEECH_TTS_PLATFORM_H_