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+/*
+ * Copyright (C) 2019-2021 Yomichan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/* global
+ * TextToSpeechAudio
+ */
+
+class AudioSystem {
+ constructor() {
+ this._fallbackAudio = null;
+ }
+
+ prepare() {
+ // speechSynthesis.getVoices() will not be populated unless some API call is made.
+ if (typeof speechSynthesis === 'undefined') { return; }
+
+ const eventListeners = new EventListenerCollection();
+ const onVoicesChanged = () => { eventListeners.removeAllEventListeners(); };
+ eventListeners.addEventListener(speechSynthesis, 'voiceschanged', onVoicesChanged, false);
+ }
+
+ getFallbackAudio() {
+ if (this._fallbackAudio === null) {
+ this._fallbackAudio = new Audio('/data/audio/button.mp3');
+ }
+ return this._fallbackAudio;
+ }
+
+ createAudio(url, source) {
+ return new Promise((resolve, reject) => {
+ const audio = new Audio(url);
+ audio.addEventListener('loadeddata', () => {
+ if (!this._isAudioValid(audio, source)) {
+ reject(new Error('Could not retrieve audio'));
+ } else {
+ resolve(audio);
+ }
+ });
+ audio.addEventListener('error', () => reject(audio.error));
+ });
+ }
+
+ createTextToSpeechAudio(text, voiceUri) {
+ const voice = this._getTextToSpeechVoiceFromVoiceUri(voiceUri);
+ if (voice === null) {
+ throw new Error('Invalid text-to-speech voice');
+ }
+ return new TextToSpeechAudio(text, voice);
+ }
+
+ // Private
+
+ _isAudioValid(audio, source) {
+ switch (source) {
+ case 'jpod101':
+ {
+ const duration = audio.duration;
+ return (
+ duration !== 5.694694 && // Invalid audio (Chrome)
+ duration !== 5.720718 // Invalid audio (Firefox)
+ );
+ }
+ default:
+ return true;
+ }
+ }
+
+ _getTextToSpeechVoiceFromVoiceUri(voiceUri) {
+ try {
+ for (const voice of speechSynthesis.getVoices()) {
+ if (voice.voiceURI === voiceUri) {
+ return voice;
+ }
+ }
+ } catch (e) {
+ // NOP
+ }
+ return null;
+ }
+}