Android implementation of text-to-speech code for Web Speech Synthesis API

chrome/android/java/src/org/chromium/chrome/browser/TtsPlatformImpl.java

+// 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.chrome.browser;
+
+import android.content.Context;
+import android.speech.tts.TextToSpeech;
+import android.speech.tts.UtteranceProgressListener;
+import java.lang.Double;
+import java.lang.Integer;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Locale;
+import org.chromium.base.CalledByNative;
+import org.chromium.base.ThreadUtils;
+
+/**
+ * This class is the Java counterpart to the C++ TtsPlatformImplAndroid class.
+ * It implements the Android-native text-to-speech code to support the web
+ * speech synthesis API.
+ */
+public class TtsPlatformImpl {
+    private class TtsVoice {
+        public String name;
+        public String language;
+    };
+
+    private int mNativeTtsPlatformImplAndroid;
+    private TextToSpeech mTextToSpeech;
+    private boolean mInitialized;
+    private ArrayList<TtsVoice> mVoices;
+    private String mCurrentLanguage;
+
+    private TtsPlatformImpl(int nativeTtsPlatformImplAndroid, Context context) {
+        mInitialized = false;
+        mNativeTtsPlatformImplAndroid = nativeTtsPlatformImplAndroid;
+        mTextToSpeech = new TextToSpeech(context, new TextToSpeech.OnInitListener() {
+                public void onInit(int status) {
+                    if (status == TextToSpeech.SUCCESS)
+                        initialize();

[David Trainor- moved to gerrit, 2013/05/15 20:55:28]

move this up on the same line as the if() or put {} around it for Java style.

[dmazzoni, 2013/05/16 07:35:13]

Done.

+                }
+            });
+        mTextToSpeech.setOnUtteranceProgressListener(new UtteranceProgressListener() {
+                public void onDone(final String utteranceId) {
+                    ThreadUtils.runOnUiThread(new Runnable() {
+                        @Override
+                        public void run() {
+                            nativeOnEndEvent(mNativeTtsPlatformImplAndroid,

[David Trainor- moved to gerrit, 2013/05/15 20:55:28]

Maybe check mNativeTtsPlatformImplAndroid for 0?  See tts_android.cc comment.

[dmazzoni, 2013/05/16 07:35:13]

Done.

+                                             Integer.parseInt(utteranceId));
+                        }
+                    });
+                }
+
+                public void onError(final String utteranceId) {
+                    ThreadUtils.runOnUiThread(new Runnable() {
+                        @Override
+                        public void run() {
+                            nativeOnErrorEvent(mNativeTtsPlatformImplAndroid,
+                                               Integer.parseInt(utteranceId));
+                        }
+                    });
+                }
+
+                public void onStart(final String utteranceId) {
+                    ThreadUtils.runOnUiThread(new Runnable() {
+                        @Override
+                        public void run() {
+                            nativeOnStartEvent(mNativeTtsPlatformImplAndroid,
+                                               Integer.parseInt(utteranceId));
+                        }
+                    });
+                }
+            });
+    };
+
+    @CalledByNative
+    public static TtsPlatformImpl create(int nativeTtsPlatformImplAndroid,

[David Trainor- moved to gerrit, 2013/05/15 20:55:28]

Put javadocs on the public methods.

[dmazzoni, 2013/05/16 07:35:13]

Done.

+                                  Context context) {
+        return new TtsPlatformImpl(nativeTtsPlatformImplAndroid, context);
+    }
+
+    @CalledByNative
+    public boolean isInitialized() {
+        return mInitialized;
+    }
+
+    @CalledByNative
+    public int getVoiceCount() {
+        return mVoices.size();

[David Trainor- moved to gerrit, 2013/05/15 20:55:28]

Would it just be safe to return 0 if mVoices is null?

[dmazzoni, 2013/05/16 07:35:13]

Sure

[dmazzoni, 2013/05/16 07:35:13]

How about I just assert mInitialized == true everywhere?

+    }
+
+    @CalledByNative
+    public String getVoiceName(int voiceIndex) {
+        return mVoices.get(voiceIndex).name;
+    }
+
+    @CalledByNative
+    public String getVoiceLanguage(int voiceIndex) {
+        return mVoices.get(voiceIndex).language;
+    }
+
+    @CalledByNative
+    public boolean speak(int utteranceId, String text, String lang,
+                         float rate, float pitch, float volume) {
+        if (lang != mCurrentLanguage) {

[David Trainor- moved to gerrit, 2013/05/15 20:55:28]

return false if !isInitialized() (and/or assert)?

[dmazzoni, 2013/05/16 07:35:13]

I like asserting better, that doesn't imply there's a legitimate reason to call
this when not initialized.

+            mTextToSpeech.setLanguage(new Locale(lang));
+            mCurrentLanguage = lang;
+        }
+
+        mTextToSpeech.setSpeechRate(rate);
+        mTextToSpeech.setPitch(pitch);
+        HashMap<String, String> params = new HashMap<String, String>();
+        if (volume != 1.0)
+            params.put(TextToSpeech.Engine.KEY_PARAM_VOLUME, Double.toString(volume));

[David Trainor- moved to gerrit, 2013/05/15 20:55:28]

{ } around this even though it's one line.

[dmazzoni, 2013/05/16 07:35:13]

Done.

+        params.put(TextToSpeech.Engine.KEY_PARAM_UTTERANCE_ID, Integer.toString(utteranceId));
+        int result = mTextToSpeech.speak(text, TextToSpeech.QUEUE_FLUSH, params);
+        return (result == TextToSpeech.SUCCESS);
+    }
+
+    @CalledByNative
+    public void stop() {
+    }
+
+    private void initialize() {
+        // Note: Android supports multiple speech engines, but querying the
+        // metadata about all of them is expensive. So we deliberately only
+        // support the default speech engine, and expose the different
+        // supported languages for the default engine as different voices.
+        String defaultEngineName = mTextToSpeech.getDefaultEngine();
+        String engineLabel = defaultEngineName;
+        for (TextToSpeech.EngineInfo info : mTextToSpeech.getEngines()) {
+            if (info.name.equals(defaultEngineName))
+                engineLabel = info.label;

[David Trainor- moved to gerrit, 2013/05/15 20:55:28]

Move up to same line as if.

[dmazzoni, 2013/05/16 07:35:13]

Done.

+        }
+        Locale[] locales = Locale.getAvailableLocales();
+        mVoices = new ArrayList<TtsVoice>();
+        for (int i = 0; i < locales.length; ++i) {
+            if (!locales[i].getVariant().isEmpty())
+                continue;

[David Trainor- moved to gerrit, 2013/05/15 20:55:28]

Move up to same line as if.

[dmazzoni, 2013/05/16 07:35:13]

Done.

+            if (mTextToSpeech.isLanguageAvailable(locales[i]) > 0) {
+                TtsVoice voice = new TtsVoice();
+                voice.name = locales[i].getDisplayLanguage();
+                if (!locales[i].getCountry().isEmpty())
+                    voice.name += " " + locales[i].getDisplayCountry();

[David Trainor- moved to gerrit, 2013/05/15 20:55:28]

Add { } around this line or move up.

If this is going to be displayed to the user, does it support RTL?  Do we need
to?

[dmazzoni, 2013/05/16 07:35:13]

Done.
Developers have the option to show these to a user, but they're not guaranteed
to be easily human-readable. I believe it will be okay - worst case "U.S.
English" and "English U.S." are equally intelligible.

Also, FWIW, I don't believe there are any TTS voices for RTL languages on
Android yet, but I could be wrong.

+                voice.language = locales[i].toString();
+                mVoices.add(voice);
+            }
+        }
+
+        mInitialized = true;
+
+        ThreadUtils.runOnUiThread(new Runnable() {
+            @Override
+            public void run() {
+                nativeVoicesChanged(mNativeTtsPlatformImplAndroid);

[David Trainor- moved to gerrit, 2013/05/15 20:55:28]

Maybe add if (mNativeTtsPlatformImplAndroid != 0)?

[dmazzoni, 2013/05/16 07:35:13]

Done.

+            }
+        });
+    }
+
+    private native void nativeVoicesChanged(int nativeTtsPlatformImplAndroid);
+    private native void nativeOnEndEvent(int nativeTtsPlatformImplAndroid, int utteranceId);
+    private native void nativeOnStartEvent(int nativeTtsPlatformImplAndroid, int utteranceId);
+    private native void nativeOnErrorEvent(int nativeTtsPlatformImplAndroid, int utteranceId);
+}