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 CONTENT_PUBLIC_BROWSER_SPEECH_RECOGNITION_EVENT_LISTENER_H_ 6 #define CONTENT_PUBLIC_BROWSER_SPEECH_RECOGNITION_EVENT_LISTENER_H_ 7 8 #include "base/basictypes.h" 9 #include "content/common/content_export.h" 10 #include "content/public/common/speech_recognition_result.h" 11 12 namespace content { 13 14 struct SpeechRecognitionError; 15 16 // The interface to be implemented by consumers interested in receiving 17 // speech recognition events. 18 class CONTENT_EXPORT SpeechRecognitionEventListener { 19 public: 20 // Invoked when the StartRequest is received and the recognition process is 21 // started. 22 virtual void OnRecognitionStart(int session_id) = 0; 23 24 // Invoked when the first audio capture is initiated. 25 virtual void OnAudioStart(int session_id) = 0; 26 27 // At the start of recognition, a short amount of audio is recorded to 28 // estimate the environment/background noise and this callback is issued 29 // after that is complete. Typically the delegate brings up any speech 30 // recognition UI once this callback is received. 31 virtual void OnEnvironmentEstimationComplete(int session_id) = 0; 32 33 // Informs that the endpointer has started detecting sound (possibly speech). 34 virtual void OnSoundStart(int session_id) = 0; 35 36 // Informs that the endpointer has stopped detecting sound (a long silence). 37 virtual void OnSoundEnd(int session_id) = 0; 38 39 // Invoked when audio capture stops, either due to the endpoint detecting 40 // silence, an internal error, or an explicit stop was issued. 41 virtual void OnAudioEnd(int session_id) = 0; 42 43 // Invoked when a result is retrieved. 44 virtual void OnRecognitionResults(int session_id, 45 const SpeechRecognitionResults& results) = 0; 46 47 // Invoked if there was an error while capturing or recognizing audio. 48 // The recognition has already been cancelled when this call is made and 49 // no more events will be raised. 50 virtual void OnRecognitionError(int session_id, 51 const SpeechRecognitionError& error) = 0; 52 53 // Informs of a change in the captured audio level, useful if displaying 54 // a microphone volume indicator while recording. 55 // The value of |volume| and |noise_volume| is in the [0.0, 1.0] range. 56 // TODO(janx): Is this necessary? It looks like only x-webkit-speech bubble 57 // uses it (see crbug.com/247351). 58 virtual void OnAudioLevelsChange(int session_id, 59 float volume, float noise_volume) = 0; 60 61 // This is guaranteed to be the last event raised in the recognition 62 // process and the |SpeechRecognizer| object can be freed if necessary. 63 virtual void OnRecognitionEnd(int session_id) = 0; 64 65 protected: 66 virtual ~SpeechRecognitionEventListener() {} 67 }; 68 69 } // namespace content 70 71 #endif // CONTENT_PUBLIC_BROWSER_SPEECH_RECOGNITION_EVENT_LISTENER_H_ 72
