Index: content/browser/speech/speech_recognition_engine.h |
diff --git a/content/browser/speech/speech_recognition_engine.h b/content/browser/speech/speech_recognition_engine.h |
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+// 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_BROWSER_SPEECH_SPEECH_RECOGNITION_ENGINE_H_ |
+#define CONTENT_BROWSER_SPEECH_SPEECH_RECOGNITION_ENGINE_H_ |
+#pragma once |
+ |
+#include <string> |
+#include <vector> |
+ |
+#include "base/basictypes.h" |
+ |
+namespace content { |
+struct SpeechRecognitionResult; |
+struct SpeechRecognitionError; |
+} |
+ |
+namespace speech { |
+ |
+class AudioChunk; |
+ |
+// This interface models the basic contract that a speech recognition engine, |
+// either working locally or relying on a remote web-service, must obey. |
+// The expected call sequence for exported methods is: |
+// StartRecognition Mandatory at beginning of SR. |
+// TakeAudioChunk For every audio chunk pushed. |
+// AudioChunksEnded Finalize the audio stream (omitted in case of errors). |
+// EndRecognition Mandatory at end of SR (even on errors). |
+// No delegate callback is allowed before Initialize() or after Cleanup(). |
+class SpeechRecognitionEngine { |
+ public: |
+ // Interface for receiving callbacks from this object. |
+ class Delegate { |
+ public: |
+ // Called whenever a result is retrieved. It might be issued several times, |
+ // (e.g., in the case of continuous speech recognition engine |
+ // implementations). |
+ virtual void OnSpeechRecognitionEngineResult( |
+ const content::SpeechRecognitionResult& result) = 0; |
+ virtual void OnSpeechRecognitionEngineError( |
+ const content::SpeechRecognitionError& error) = 0; |
+ |
+ protected: |
+ virtual ~Delegate() {} |
+ }; |
+ |
+ virtual ~SpeechRecognitionEngine() {} |
+ |
+ // Called when the speech recognition begins, before any TakeAudioChunk call. |
+ virtual void StartRecognition() = 0; |
+ |
+ // End any recognition activity and don't make any further callback. |
+ // Must be always called to close the corresponding StartRecognition call, |
+ // even in case of errors. |
+ // No further TakeAudioChunk/AudioChunksEnded calls are allowed after this. |
+ virtual void EndRecognition() = 0; |
+ |
+ // Push a chunk of uncompressed audio data, where the chunk length agrees with |
+ // GetDesiredAudioChunkDurationMs(). |
+ virtual void TakeAudioChunk(const AudioChunk& data) = 0; |
+ |
+ // Notifies the engine that audio capture has completed and no more chunks |
+ // will be pushed. The engine, however, can still provide further results |
+ // using the audio chunks collected so far. |
+ virtual void AudioChunksEnded() = 0; |
+ |
+ // Checks wheter recognition of pushed audio data is pending. |
+ virtual bool IsRecognitionPending() const = 0; |
+ |
+ // Retrieves the desired duration, in milliseconds, of pushed AudioChunk(s). |
+ virtual int GetDesiredAudioChunkDurationMs() const = 0; |
+ |
+ // set_delegate detached from constructor for lazy dependency injection. |
+ void set_delegate(Delegate* delegate) { delegate_ = delegate; } |
+ |
+ protected: |
+ Delegate* delegate() const { return delegate_; } |
+ |
+ private: |
+ Delegate* delegate_; |
+}; |
+ |
+// This typedef is to workaround the issue with certain versions of |
+// Visual Studio where it gets confused between multiple Delegate |
+// classes and gives a C2500 error. (I saw this error on the try bots - |
+// the workaround was not needed for my machine). |
+typedef SpeechRecognitionEngine::Delegate SpeechRecognitionEngineDelegate; |
+ |
+} // namespace speech |
+ |
+#endif // CONTENT_BROWSER_SPEECH_SPEECH_RECOGNITION_ENGINE_H_ |