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..ac3c9b3467ccd8cc207472106ec6f68002b060b5
--- /dev/null
+++ b/content/public/android/java/src/org/chromium/content/browser/SpeechRecognition.java
@@ -0,0 +1,141 @@
+// 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 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 {

[janx, 2013/06/07 12:43:58]

Peter Beverloo 2013/06/06 11:48:13
In general, I feel this class can do with a little bit more documentation. At
least having some descriptions of the exposed-to-native API would be nice.

+
+    private Intent mIntent = null;
+    private Context mContext = null;
+    private boolean mContinuous = false;
+    private SpeechRecognizer mRecognizer = null;
+    private RecognitionListener mListener = null;
+    private int mNativeSpeechRecognizerImplAndroid = 0;

[janx, 2013/06/07 12:43:58]

Primiano Tucci 2013/06/03 16:24:11
You'll need a reviewer for someone more experienced than me on this .java file
:).
Is this the right way to issue callbacks between Java and C++?

[bulach, 2013/06/07 15:35:10]

I suppose almost all of these could be final and initialized only in the ctor
rather than here (except probably the mRecognizer since it needs to be
destroy()).

[janx, 2013/06/10 16:51:18]

I moved all initializations into the ctor and made every member final except
mRecognizer (as you pointed out, it needs to be destroyed) and mContinuous (it
changes when you call startRecognition).

+
+    class Listener implements RecognitionListener {
+        @Override
+        public void onBeginningOfSpeech() {
+            nativeOnSoundStartJNI(mNativeSpeechRecognizerImplAndroid);
+        }
+
+        @Override
+        public void onBufferReceived(byte[] buffer) { }
+
+        @Override
+        public void onEndOfSpeech() {
+            nativeOnSoundEndJNI(mNativeSpeechRecognizerImplAndroid);
+            // Since Android doesn't have a dedicated event for when audio
+            // capture is finished, we fire it after speech has ended.
+            nativeOnAudioEndJNI(mNativeSpeechRecognizerImplAndroid);
+        }
+
+        @Override
+        public void onError(int error) {
+            nativeOnRecognitionErrorJNI(mNativeSpeechRecognizerImplAndroid, error);
+            terminate();
+        }
+
+        @Override
+        public void onEvent(int event, Bundle bundle) { }
+
+        @Override
+        public void onPartialResults(Bundle bundle) {
+            handleResults(bundle, true);
+        }
+
+        @Override
+        public void onReadyForSpeech(Bundle bundle) {
+            nativeOnAudioStartJNI(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);
+            nativeOnRecognitionResultsJNI(mNativeSpeechRecognizerImplAndroid, results, scores,
+                provisional);
+        }
+    }
+
+    private SpeechRecognition(final Context context, int nativeSpeechRecognizerImplAndroid) {
+        mContext = context;
+        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;
+        nativeOnRecognitionEndJNI(mNativeSpeechRecognizerImplAndroid);
+    }
+
+    @CalledByNative
+    public static SpeechRecognition createSpeechRecognition(Context context,

[bulach, 2013/06/07 15:35:10]

nit: we tend to keep @CalledByNative private, since they aren't called by
java... (that is, we only use the visibility modifiers here for java itself..)

[janx, 2013/06/10 16:51:18]

Ok thanks, changed to private. I wasn't sure how this would affect the JNI
interface.

+            int nativeSpeechRecognizerImplAndroid) {
+        return new SpeechRecognition(context, nativeSpeechRecognizerImplAndroid);
+    }
+
+    @CalledByNative
+    public void StartRecognition(boolean continuous, boolean interim_results) {

[bulach, 2013/06/07 15:35:10]

nit:s/Start/start/, below s/Abort/abort/ and s/Stop/stop/ (i.e., java naming
convention)

[janx, 2013/06/10 16:51:18]

Fixed.

+        mContinuous = continuous;
+        mIntent.putExtra("android.speech.extra.DICTATION_MODE", continuous);
+        mIntent.putExtra(RecognizerIntent.EXTRA_PARTIAL_RESULTS, interim_results);
+        mRecognizer.startListening(mIntent);
+    }
+
+    @CalledByNative
+    public void AbortRecognition() {
+        mRecognizer.cancel();
+        terminate();
+    }
+
+    @CalledByNative
+    public void StopRecognition() {
+        mContinuous = false;
+        mRecognizer.stopListening();
+    }
+
+    private native void nativeOnAudioStartJNI(int nativeSpeechRecognizerImplAndroid);

[bulach, 2013/06/07 15:35:10]

nit: remove all JNI suffix.

[janx, 2013/06/10 16:51:18]

Done.

+    private native void nativeOnSoundStartJNI(int nativeSpeechRecognizerImplAndroid);
+    private native void nativeOnSoundEndJNI(int nativeSpeechRecognizerImplAndroid);
+    private native void nativeOnAudioEndJNI(int nativeSpeechRecognizerImplAndroid);
+    private native void nativeOnRecognitionResultsJNI(int nativeSpeechRecognizerImplAndroid,
+        String[] results, float[] scores, boolean provisional);
+    private native void nativeOnRecognitionErrorJNI(int nativeSpeechRecognizerImplAndroid,
+        int error);
+    private native void nativeOnRecognitionEndJNI(int nativeSpeechRecognizerImplAndroid);
+}