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

chrome/browser/speech/tts_android.cc

+// 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.
+
+#include "chrome/browser/speech/tts_android.h"
+
+#include <string>
+
+#include "base/android/jni_string.h"
+#include "base/memory/singleton.h"
+#include "base/utf_string_conversions.h"
+#include "chrome/browser/speech/tts_controller.h"
+#include "jni/TtsPlatformImpl_jni.h"
+
+using base::android::AttachCurrentThread;
+
+// static
+TtsPlatformImpl* TtsPlatformImpl::GetInstance() {
+  return TtsPlatformImplAndroid::GetInstance();
+}
+
+TtsPlatformImplAndroid::TtsPlatformImplAndroid()
+    : utterance_id_(0) {
+  JNIEnv* env = AttachCurrentThread();
+  java_ref_.Reset(
+      Java_TtsPlatformImpl_create(env,
+                                  reinterpret_cast<jint>(this),
+                                  base::android::GetApplicationContext()));
+}
+
+TtsPlatformImplAndroid::~TtsPlatformImplAndroid() {
+  JNIEnv* env = AttachCurrentThread();
+  Java_TtsPlatformImpl_destroy(env, java_ref_.obj());
+}
+
+bool TtsPlatformImplAndroid::Speak(
+    int utterance_id,
+    const std::string& utterance,
+    const std::string& lang,
+    const VoiceData& voice,
+    const UtteranceContinuousParameters& params) {
+  JNIEnv* env = AttachCurrentThread();
+  if (!Java_TtsPlatformImpl_isInitialized(env, java_ref_.obj()))
+    return false;
+
+  jboolean success = Java_TtsPlatformImpl_speak(
+      env, java_ref_.obj(),
+      utterance_id,
+      base::android::ConvertUTF8ToJavaString(env, utterance).Release(),
+      base::android::ConvertUTF8ToJavaString(env, lang).Release(),
+      params.rate, params.pitch, params.volume);
+  if (success) {

[bulach, 2013/05/16 11:10:28]

nit: the "else" is unecessary, and it'd probably be easier to read as:

if (!success)
  return false;
utterance_ = utterance;
utterance_id_ = utterance_id;
return true;

[dmazzoni, 2013/05/16 16:36:40]

Done.

+    utterance_ = utterance;
+    utterance_id_ = utterance_id;
+    return true;
+  } else {
+    return false;
+  }
+}
+
+bool TtsPlatformImplAndroid::StopSpeaking() {
+  JNIEnv* env = AttachCurrentThread();
+  Java_TtsPlatformImpl_stop(env, java_ref_.obj());
+  utterance_id_ = 0;
+  utterance_.clear();
+  return true;
+}
+
+bool TtsPlatformImplAndroid::IsSpeaking() {
+  return (utterance_id_ != 0);
+}
+
+void TtsPlatformImplAndroid::GetVoices(
+    std::vector<VoiceData>* out_voices) {
+  JNIEnv* env = AttachCurrentThread();
+  if (!Java_TtsPlatformImpl_isInitialized(env, java_ref_.obj()))
+    return;
+
+  int count = Java_TtsPlatformImpl_getVoiceCount(env, java_ref_.obj());
+  for (int i = 0; i < count; ++i) {
+    out_voices->push_back(VoiceData());
+    VoiceData& data = out_voices->back();

[bulach, 2013/05/16 11:10:28]

I think we don't normally use mutable refs.. presumably VoiceData is
copy-constructable, right?
perhaps:
 VoiceData data;
 data.native = true;
 data.... = ...;
 ...
 out_voices->push_back(data);

[dmazzoni, 2013/05/16 16:36:40]

I'm using this pattern consistently in chrome/browser/speech and it's sometimes
used elsewhere - I agree it requires caution, but I think it's allowed when used
safely.

+    data.native = true;
+    data.name = base::android::ConvertJavaStringToUTF8(
+        Java_TtsPlatformImpl_getVoiceName(env, java_ref_.obj(), i));
+    data.lang = base::android::ConvertJavaStringToUTF8(
+        Java_TtsPlatformImpl_getVoiceLanguage(env, java_ref_.obj(), i));
+    data.gender = TTS_GENDER_NONE;
+    data.events.insert(TTS_EVENT_START);
+    data.events.insert(TTS_EVENT_END);
+    data.events.insert(TTS_EVENT_ERROR);
+  }
+}
+
+void TtsPlatformImplAndroid::VoicesChanged(JNIEnv* env, jobject obj) {
+  TtsController::GetInstance()->VoicesChanged();
+}
+
+void TtsPlatformImplAndroid::OnEndEvent(
+    JNIEnv* env, jobject obj, jint utterance_id) {
+  if (utterance_id != utterance_id_)
+    return;
+
+  TtsController::GetInstance()->OnTtsEvent(
+      utterance_id_, TTS_EVENT_END, utterance_.size(), std::string());
+  utterance_id_ = 0;
+  utterance_.clear();

[bulach, 2013/05/16 11:10:28]

nit: 100-107 is fairly similar to 112-118, so perhaps extract it into a
"SendFinalTTSEvent(utterance_id, event, size)" ?

[dmazzoni, 2013/05/16 16:36:40]

Done.

+}
+
+void TtsPlatformImplAndroid::OnErrorEvent(
+    JNIEnv* env, jobject obj, jint utterance_id) {
+  if (utterance_id != utterance_id_)
+    return;
+
+  TtsController::GetInstance()->OnTtsEvent(
+      utterance_id_, TTS_EVENT_ERROR, 0, std::string());
+  utterance_id_ = 0;
+  utterance_.clear();
+}
+
+void TtsPlatformImplAndroid::OnStartEvent(
+    JNIEnv* env, jobject obj, jint utterance_id) {
+  if (utterance_id != utterance_id_)
+    return;
+
+  TtsController::GetInstance()->OnTtsEvent(
+      utterance_id_, TTS_EVENT_START, 0, std::string());
+}
+
+// static
+TtsPlatformImplAndroid* TtsPlatformImplAndroid::GetInstance() {
+  return Singleton<TtsPlatformImplAndroid>::get();
+}
+
+// static
+bool TtsPlatformImplAndroid::Register(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}