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..3ad04268dc22f90c896080c5fd7535800ed376d1
--- /dev/null
+++ b/content/public/android/java/src/org/chromium/content/browser/SpeechRecognition.java
@@ -0,0 +1,126 @@
+// 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 android.widget.Toast;

[Peter Beverloo, 2013/06/06 11:48:13]

I don't think you are using Toast.

[janx, 2013/06/06 16:09:37]

Nor am I using ThreadUtils or FutureTask. Nice catch, thanks.

+
+import org.chromium.base.CalledByNative;
+import org.chromium.base.JNINamespace;
+import org.chromium.base.ThreadUtils;

[Peter Beverloo, 2013/06/06 11:48:13]

I don't think you are using ThreadUtils.

+
+import java.util.ArrayList;
+import java.util.concurrent.FutureTask;
+
+/**
+ * Android speech recognition adapter.
+ */
+@JNINamespace("content")
+class SpeechRecognition {

[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 intent = null;

[Peter Beverloo, 2013/06/06 11:48:13]

s/intent/mIntent/

+    private Context mContext = null;
+    private boolean mContinuous = false;
+    private SpeechRecognizer recognizer = null;

[Peter Beverloo, 2013/06/06 11:48:13]

s/recognizer/mRecognizer/

[janx, 2013/06/06 16:09:37]

Done reluctantly.

+    private RecognitionListener listener = null;

[Peter Beverloo, 2013/06/06 11:48:13]

s/listener/mListener/

+    private int mNativeSpeechRecognizerImplAndroid = 0;

[janx, 2013/06/06 09:34:55]

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++?

+
+    class Listener implements RecognitionListener {
+        @Override

[Peter Beverloo, 2013/06/06 11:48:13]

Java really should have some kind of @Implements to complement @Override, since
this technically doesn't override anything.

[janx, 2013/06/06 16:09:37]

Maybe you should file a bug at http://bugreport.sun.com/bugreport/.

+        public void onBeginningOfSpeech() {
+            nativeOnSoundStartJNI(mNativeSpeechRecognizerImplAndroid);
+        }
+        @Override
+        public void onBufferReceived(byte[] buffer) { }
+        @Override
+        public void onEndOfSpeech() {
+            nativeOnSoundEndJNI(mNativeSpeechRecognizerImplAndroid);
+            // Since there is no AudioEnd event, we emulate it.

[Peter Beverloo, 2013/06/06 11:48:13]

Maybe rephrase this as something like "Android doesn't have an event similar to
the speech API's onaudioend event. Fire it now as this is the most appropriate
place to do so."?

[janx, 2013/06/06 16:09:37]

Rephrased to something similar.

+            nativeOnAudioEndJNI(mNativeSpeechRecognizerImplAndroid);
+        }
+        @Override
+        public void onError(int error) {
+            nativeOnRecognitionErrorJNI(mNativeSpeechRecognizerImplAndroid, error);
+            terminate();
+        }
+        @Override
+        public void onEvent(int event, Bundle bundle) { }

[Peter Beverloo, 2013/06/06 11:48:13]

nit: even when empty, please have an empty line between methods.

[janx, 2013/06/06 16:09:37]

Done.

+        @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();

[Peter Beverloo, 2013/06/06 11:48:13]

If we don't call terminate() here, will it just restart?  How are we handling
recognition services which don't support continuous mode?

[janx, 2013/06/06 16:09:37]

The way it behaves now is that if mContinuous is true, and continuous mode is
not supported, the recognition stalls (after yielding the first final result, it
doesn't stop but doesn't restart and doesn't yield further results).

+        }
+        @Override
+        public void onRmsChanged(float rms) { }
+        public void handleResults(Bundle bundle, boolean provisional) {

[Peter Beverloo, 2013/06/06 11:48:13]

This method can be private.

[janx, 2013/06/06 16:09:37]

Done.

+            ArrayList<String> list = bundle.getStringArrayList(SpeechRecognizer.RESULTS_RECOGNITION);

[Peter Beverloo, 2013/06/06 11:48:13]

nit: line length limit in Java is a hundred characters. Elsewhere in this file
too.

[janx, 2013/06/06 16:09:37]

Done.

+            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;
+        listener = new Listener();
+        intent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
+        recognizer = SpeechRecognizer.createSpeechRecognizer(mContext);

[Peter Beverloo, 2013/06/06 11:48:13]

While more of a follow up, have you thought about using
SpeechRecognizer.isRecognitionAvailable() to gracefully disable the speech
recognition feature if the system can't provide it?

[janx, 2013/06/06 16:09:37]

Yes, I think that we could easily make a JNI call to a static Java method
returning SpeechRecognizer.isRecognitionAvailable() when deciding whether to
activate the feature in Blink (e.g. near
https://code.google.com/p/chromium/codesearch#chromium/src/content/renderer/r...).

+        recognizer.setRecognitionListener(listener);
+    }
+
+    private void terminate() {
+        recognizer.destroy();
+        recognizer = null;
+        nativeOnRecognitionEndJNI(mNativeSpeechRecognizerImplAndroid);
+    }
+
+    @CalledByNative
+    public static SpeechRecognition createSpeechRecognition(Context context, int nativeSpeechRecognizerImplAndroid) {
+        return new SpeechRecognition(context, nativeSpeechRecognizerImplAndroid);
+    }
+
+    @CalledByNative
+    public void StartRecognition(boolean continuous, boolean interim_results) {
+        mContinuous = continuous;
+        intent.putExtra("android.speech.extra.DICTATION_MODE", continuous);
+        intent.putExtra(RecognizerIntent.EXTRA_PARTIAL_RESULTS, interim_results);
+        recognizer.startListening(intent);
+    }
+
+    @CalledByNative
+    public void AbortRecognition() {
+        recognizer.cancel();
+        terminate();
+    }
+
+    @CalledByNative
+    public void StopRecognition() {
+        mContinuous = false;
+        recognizer.stopListening();
+    }
+
+    private native void nativeOnAudioStartJNI(int nativeSpeechRecognizerImplAndroid);
+    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);
+}