Implement SpeechRecognizerImplAndroid

content/public/android/java/src/org/chromium/content/browser/SpeechRecognition.java

Index: content/public/android/java/src/org/chromium/content/browser/SpeechRecognition.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/SpeechRecognition.java b/content/public/android/java/src/org/chromium/content/browser/SpeechRecognition.java
new file mode 100644
index 0000000000000000000000000000000000000000..92ac8166d77e5a46b0c2ecde39c234dbc438604d
--- /dev/null
+++ b/content/public/android/java/src/org/chromium/content/browser/SpeechRecognition.java
@@ -0,0 +1,173 @@
+// Copyright (c) 2013 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.
+
+package org.chromium.content.browser;
+
+import android.content.Context;
+import android.content.Intent;
+import android.os.Bundle;
+import android.speech.RecognitionListener;
+import android.speech.RecognizerIntent;
+import android.speech.SpeechRecognizer;
+
+import org.chromium.base.CalledByNative;
+import org.chromium.base.JNINamespace;
+import org.chromium.content.browser.SpeechRecognitionError;
+
+import java.util.ArrayList;
+
+/**
+ * This class uses Android's SpeechRecognizer to perform speech recognition for
+ * the Web Speech API on Android. Using Android's platform recognizer offers
+ * several benefits, like good quality and good local fallback when no data
+ * connection is available.
+ */
+@JNINamespace("content")
+class SpeechRecognition {
+
+    private boolean mContinuous;
+    private SpeechRecognizer mRecognizer;

[bulach, 2013/06/11 07:24:48]

nit: put the final members first

[janx, 2013/06/12 14:47:14]

Done.

+    private final Context mContext;
+    private final Intent mIntent;
+    private final int mNativeSpeechRecognizerImplAndroid;
+    private final RecognitionListener mListener;
+
+    class Listener implements RecognitionListener {
+        @Override
+        public void onBeginningOfSpeech() {
+            nativeOnSoundStart(mNativeSpeechRecognizerImplAndroid);
+        }
+
+        @Override
+        public void onBufferReceived(byte[] buffer) { }
+
+        @Override
+        public void onEndOfSpeech() {
+            nativeOnSoundEnd(mNativeSpeechRecognizerImplAndroid);
+            // Since Android doesn't have a dedicated event for when audio
+            // capture is finished, we fire it after speech has ended.
+            nativeOnAudioEnd(mNativeSpeechRecognizerImplAndroid);
+        }
+
+        @Override
+        public void onError(int error) {

[Primiano Tucci (use gerrit), 2013/06/11 13:34:51]

In which order (relatively to onEndOfSpeech) is the onError event dispatched?
Are we keeping the same order of events in case of errors of Chrome desktop
(i.e. speech_recognizer_impl.cc), that is:
onSoundEnd -> onAudioEnd -> onError -> onRecognitionEnd ?
(see
https://code.google.com/p/chromium/codesearch#chromium/src/content/browser/sp...)

[janx, 2013/06/12 14:47:14]

The order is the same as on desktop except in one edge case: when an error
happens before SoundEnd/AudioEnd, e.g. if the user calls abort() before those
events. In this edge case, OnSoundEnd/OnAudioEnd are not called at all. This
doesn't break anything on the client side, because the most important
onRecognitionEnd is called properly, but is asymmetric to what happens on
desktop.

In order to guarantee that events are called in the same way on mobile as on
desktop, I made terminate() state-aware so that it can throw ending events and
tear down properly.

+            int code = -1;
+
+            // Translate Android speech recognition errors to Web Speech API errors.
+            switch(error) {
+              case SpeechRecognizer.ERROR_AUDIO:
+                code = SpeechRecognitionError.AUDIO;
+                break;
+              case SpeechRecognizer.ERROR_CLIENT:
+                code = SpeechRecognitionError.ABORTED;
+                break;
+              case SpeechRecognizer.ERROR_RECOGNIZER_BUSY:
+              case SpeechRecognizer.ERROR_INSUFFICIENT_PERMISSIONS:
+                code = SpeechRecognitionError.NOT_ALLOWED;
+                break;
+              case SpeechRecognizer.ERROR_NETWORK_TIMEOUT:
+              case SpeechRecognizer.ERROR_NETWORK:
+              case SpeechRecognizer.ERROR_SERVER:
+                code = SpeechRecognitionError.NETWORK;
+                break;
+              case SpeechRecognizer.ERROR_NO_MATCH:
+                code = SpeechRecognitionError.NO_MATCH;
+                break;
+              case SpeechRecognizer.ERROR_SPEECH_TIMEOUT:
+                code = SpeechRecognitionError.NO_SPEECH;
+                break;
+              default:
+                assert false;
+                return;
+            }
+
+            nativeOnRecognitionError(mNativeSpeechRecognizerImplAndroid, code);
+            terminate();
+        }
+
+        @Override
+        public void onEvent(int event, Bundle bundle) { }
+
+        @Override
+        public void onPartialResults(Bundle bundle) {
+            handleResults(bundle, true);
+        }
+
+        @Override
+        public void onReadyForSpeech(Bundle bundle) {
+            nativeOnAudioStart(mNativeSpeechRecognizerImplAndroid);
+        }
+
+        @Override
+        public void onResults(Bundle bundle) {
+            handleResults(bundle, false);
+            if (!mContinuous)
+                terminate();
+        }
+
+        @Override
+        public void onRmsChanged(float rms) { }
+
+        private void handleResults(Bundle bundle, boolean provisional) {
+            ArrayList<String> list =
+                bundle.getStringArrayList(SpeechRecognizer.RESULTS_RECOGNITION);
+            String[] results = list.toArray(new String[list.size()]);
+            float[] scores = bundle.getFloatArray(SpeechRecognizer.CONFIDENCE_SCORES);
+            nativeOnRecognitionResults(mNativeSpeechRecognizerImplAndroid, results, scores,
+                provisional);
+        }
+    }
+
+    private SpeechRecognition(final Context context, int nativeSpeechRecognizerImplAndroid) {
+        mContext = context;
+        mContinuous = false;
+        mNativeSpeechRecognizerImplAndroid = nativeSpeechRecognizerImplAndroid;
+        mListener = new Listener();
+        mIntent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
+        mRecognizer = SpeechRecognizer.createSpeechRecognizer(mContext);
+        mRecognizer.setRecognitionListener(mListener);
+    }
+
+    private void terminate() {
+        mRecognizer.destroy();
+        mRecognizer = null;
+        nativeOnRecognitionEnd(mNativeSpeechRecognizerImplAndroid);

[Primiano Tucci (use gerrit), 2013/06/11 13:34:51]

At this point you should reset the native pointer
(mNativeSpeechRecognizerImplAndroid).
As per definition of OnRecognitionEnd event (see
https://code.google.com/p/chromium/codesearch#chromium/src/content/public/bro...)
you must "promise" that no more events will come, so the caller can safely
destroy the object.
The easiest way for respecting this contract is resetting the native pointer
(i.e. mNativeSpeechRecognizerImplAndroid = 0)

[janx, 2013/06/12 14:47:14]

Done.

+    }
+
+    @CalledByNative
+    private static SpeechRecognition createSpeechRecognition(Context context,
+            int nativeSpeechRecognizerImplAndroid) {
+        return new SpeechRecognition(context, nativeSpeechRecognizerImplAndroid);
+    }
+
+    @CalledByNative
+    private void startRecognition(boolean continuous, boolean interim_results) {
+        mContinuous = continuous;
+        mIntent.putExtra("android.speech.extra.DICTATION_MODE", continuous);
+        mIntent.putExtra(RecognizerIntent.EXTRA_PARTIAL_RESULTS, interim_results);
+        mRecognizer.startListening(mIntent);
+    }
+
+    @CalledByNative
+    private void abortRecognition() {
+        mRecognizer.cancel();
+        terminate();
+    }
+
+    @CalledByNative
+    private void stopRecognition() {
+        mContinuous = false;
+        mRecognizer.stopListening();
+    }
+
+    private native void nativeOnAudioStart(int nativeSpeechRecognizerImplAndroid);
+    private native void nativeOnSoundStart(int nativeSpeechRecognizerImplAndroid);
+    private native void nativeOnSoundEnd(int nativeSpeechRecognizerImplAndroid);
+    private native void nativeOnAudioEnd(int nativeSpeechRecognizerImplAndroid);
+    private native void nativeOnRecognitionResults(int nativeSpeechRecognizerImplAndroid,
+        String[] results, float[] scores, boolean provisional);
+    private native void nativeOnRecognitionError(int nativeSpeechRecognizerImplAndroid,
+        int error);
+    private native void nativeOnRecognitionEnd(int nativeSpeechRecognizerImplAndroid);
+}