ui/file_manager/audio_player/js/background.js

// Copyright 2014 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.

/**
 * Icon of the audio player.
 * Use maximum size and let ash downsample the icon.
 *
 * @type {!string}
 * @const
 */
const AUDIO_PLAYER_ICON = 'icons/audio-player-192.png';

/**
 * HTML source of the audio player.
 * @type {!string}
 * @const
 */
const AUDIO_PLAYER_APP_URL = 'audio_player.html';

/**
 * Configuration of the audio player.
 * @type {!Object}
 * @const
 */
const audioPlayerCreateOptions = {
  id: 'audio-player',
  minHeight: 4 + 48 + 96,  // 4px: border-top, 48px: track, 96px: controller
  minWidth: 320,
  height: 4 + 48 + 96,  // collapsed
  width: 320,
  frame: {color: '#fafafa'}
};

class AudioPlayerBackground extends BackgroundBase {
  constructor() {
    super();
  }

  /**
   * Called when an audio player app is restarted.
   */
  onRestarted_() {
    audioPlayer.reopen(function() {
      // If the audioPlayer is reopened, change its window's icon. Otherwise
      // there is no reopened window so just skip the call of setIcon.
      if (audioPlayer.rawAppWindow) {
        audioPlayer.setIcon(AUDIO_PLAYER_ICON);
      }
    });
  }
}

/**
 * Backgound object. This is necessary for AppWindowWrapper.
 * @type {!AudioPlayerBackground}
 */
// eslint-disable-next-line no-var
var background = new AudioPlayerBackground();

/**
 * Audio player app window wrapper.
 * @type {!SingletonAppWindowWrapper}
 */
const audioPlayer = new SingletonAppWindowWrapper(
    AUDIO_PLAYER_APP_URL, audioPlayerCreateOptions);

/**
 * Opens the audio player window.
 * @param {!Array<string>} urls List of audios to play and index to start
 *     playing.
 * @return {!Promise} Promise to be fulfilled on success, or rejected on error.
 */
function open(urls) {
  let position = 0;
  const startUrl = (position < urls.length) ? urls[position] : '';

  return new Promise(function(fulfill, reject) {
           if (urls.length === 0) {
             reject('No file to open.');
             return;
           }

           // Gets the current list of the children of the parent.
           window.webkitResolveLocalFileSystemURL(urls[0], function(fileEntry) {
             fileEntry.getParent(function(parentEntry) {
               const dirReader = parentEntry.createReader();
               let entries = [];

               // Call the reader.readEntries() until no more results are
               // returned.
               const readEntries = function() {
                 dirReader.readEntries(function(results) {
                   if (!results.length) {
                     fulfill(entries.sort(util.compareName));
                   } else {
                     entries =
                         entries.concat(Array.prototype.slice.call(results, 0));
                     readEntries();
                   }
                 }, reject);
               };

               // Start reading.
               readEntries();
             }, reject);
           }, reject);
         })
      .then(function(entries) {
        // Omits non-audio files.
        const audioEntries = entries.filter(FileType.isAudio);

        // Adjusts the position to start playing.
        const maybePosition =
            util.entriesToURLs(audioEntries).indexOf(startUrl);
        if (maybePosition !== -1) {
          position = maybePosition;
        }

        // Opens the audio player.
        const urls = util.entriesToURLs(audioEntries);
        return audioPlayer.launch({items: urls, position: position}, false);
      })
      .then(function() {
        audioPlayer.setIcon(AUDIO_PLAYER_ICON);
        audioPlayer.rawAppWindow.focus();
        return AUDIO_PLAYER_APP_URL;
      })
      .catch(function(error) {
        console.error('Launch failed: ' + (error.stack || error));
        return Promise.reject(error);
      });
}

background.setLaunchHandler(open);