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..f374c7d61479b7983f22bd0730109233414e49e6
--- /dev/null
+++ b/content/public/android/java/src/org/chromium/content/browser/SpeechRecognition.java
@@ -0,0 +1,189 @@
+// 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 final Context mContext;
+    private final Intent mIntent;
+    private final RecognitionListener mListener;

[Primiano Tucci (use gerrit), 2013/06/13 10:05:05]

Ultra-nit: can you move it to line 39, just below mRecognizer, so it is more
clear that this is the listener for the mRecognizer?

[janx, 2013/06/13 16:08:53]

This ultra-nit conflicts with: "bulach 2013/06/11 07:24:48 nit: put the final
members first".

+    private final int STATE_IDLE = 0;

[Primiano Tucci (use gerrit), 2013/06/13 10:05:05]

Nit: +static (i.e. private static final int). Here and the two lines below.
Also move the static constants on the top (line 29), before the other fields.

[Peter Beverloo, 2013/06/13 11:46:23]

Agreed. Please also add a comment that they are equal to the C++ constants.

[Primiano Tucci (use gerrit), 2013/06/13 13:50:04]

Hmm I think they're not really the same and btw there is no functional
dependency with them. These constants respond to a local (i.e. Java-only) need,
which is closing the OnAudio... event properly in any situation. Unfortunately
the Android API don't do that for us, so he has to take care of this additional
level of detail here.

[janx, 2013/06/13 16:08:53]

Done.

+    private final int STATE_AWAITING_SPEECH = 1;
+    private final int STATE_CAPTURING_SPEECH = 2;
+    private int mState;
+    private int mNativeSpeechRecognizerImplAndroid;
+    private boolean mContinuous;
+    private SpeechRecognizer mRecognizer;
+
+    class Listener implements RecognitionListener {

[Peter Beverloo, 2013/06/13 11:46:23]

You never replied to my comment about method in this class having a little bit
more documentation (patch set 2).  Can you please do that?

[janx, 2013/06/13 16:08:53]

I did add a little more documentation and recycled the comment a few times to
see if other reviewers shared the concern. I now went ahead and added more
comments and explanations.

+        @Override
+        public void onBeginningOfSpeech() {
+            mState = STATE_CAPTURING_SPEECH;
+            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);
+            mState = STATE_IDLE;
+        }
+
+        @Override
+        public void onError(int error) {
+            int code = SpeechRecognitionError.NONE;
+
+            // Translate Android speech recognition errors to Web Speech API errors.
+            switch(error) {
+              case SpeechRecognizer.ERROR_AUDIO:

[Peter Beverloo, 2013/06/13 11:46:23]

nit: indent, should be four spaces per level.

[janx, 2013/06/13 16:08:53]

Done.

+                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;
+            }
+
+            terminate(code);
+        }
+
+        @Override
+        public void onEvent(int event, Bundle bundle) { }
+
+        @Override
+        public void onPartialResults(Bundle bundle) {
+            handleResults(bundle, true);
+        }
+
+        @Override
+        public void onReadyForSpeech(Bundle bundle) {
+            mState = STATE_AWAITING_SPEECH;
+            nativeOnAudioStart(mNativeSpeechRecognizerImplAndroid);
+        }
+
+        @Override
+        public void onResults(Bundle bundle) {
+            handleResults(bundle, false);
+            if (!mContinuous)
+                terminate(SpeechRecognitionError.NONE);
+        }
+
+        @Override
+        public void onRmsChanged(float rms) { }
+
+        private void handleResults(Bundle bundle, boolean provisional) {
+            ArrayList<String> list =
+                bundle.getStringArrayList(SpeechRecognizer.RESULTS_RECOGNITION);

[Peter Beverloo, 2013/06/13 11:46:23]

nit: should have eight space indent (continuation).

[janx, 2013/06/13 16:08:53]

Done.

+            String[] results = list.toArray(new String[list.size()]);
+            float[] scores = bundle.getFloatArray(SpeechRecognizer.CONFIDENCE_SCORES);
+            nativeOnRecognitionResults(mNativeSpeechRecognizerImplAndroid, results, scores,
+                provisional);

[Peter Beverloo, 2013/06/13 11:46:23]

nit: should have eight space indent (continuation).

[janx, 2013/06/13 16:08:53]

Done.

+        }
+    }
+
+    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(int error) {
+        if (mState != STATE_IDLE) {
+            if (mState == STATE_CAPTURING_SPEECH) {
+                nativeOnSoundEnd(mNativeSpeechRecognizerImplAndroid);
+            }
+            nativeOnAudioEnd(mNativeSpeechRecognizerImplAndroid);
+            mState = STATE_IDLE;
+        }
+        if (error != SpeechRecognitionError.NONE)
+            nativeOnRecognitionError(mNativeSpeechRecognizerImplAndroid, error);
+        mRecognizer.destroy();
+        mRecognizer = null;
+        nativeOnRecognitionEnd(mNativeSpeechRecognizerImplAndroid);
+        mNativeSpeechRecognizerImplAndroid = 0;
+    }
+
+    @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();

[Primiano Tucci (use gerrit), 2013/06/13 10:05:05]

I fear that if someone (i.e. the S.R. manager) calls abortRecognition twice in a
row here you will get NullPointerException.
In the original design the manager was engineer to be "politically correct",
i.e. never call abort twice, and only make calls which make sense.
However, taking a look back to the git history, it seems that this principle has
been later violated, and I fear that there are corner cases in which the S.R.
manager can call abortRecognition twice (or stop + abort) on the poor
recognizers.
In essence, would be nice if here (and similarly in start and stopRecognition) 
you just add a check on mRecognizer != NULL.

[janx, 2013/06/13 16:08:53]

Done.

+        terminate(SpeechRecognitionError.ABORTED);
+    }
+
+    @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);
+}