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gaia/apps/system/js/logo_loader.js

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+'use strict';
+
+(function(exports) {
+
+  /**
+   * LogoLoader loads either a video or image for display during phone boot.
+   * Only a single resource will be selected depending on what is availble
+   * on the filesystem.
+   * @class LogoLoader
+   * @param {Object} logoPath Contains file paths for both a video and image.
+   */
+  function LogoLoader(logoPath) {
+    // Load video / image if exist.
+    // Only one of them should success.  We load both of them at the same time.
+    this.videoPath = logoPath.video;
+    this.imagePath = logoPath.image;
+
+    this._noImage = false;
+    this._noVideo = false;
+
+    //Statuses
+    this.ready = false;
+    this.found = false;
+
+    this.element = null;
+
+    //Callback functions
+    this.onnotfound = null;
+    this.onload = null;
+
+    this._initVideo();
+    this._initImage();
+  }
+
+  LogoLoader.prototype = {
+
+    /**
+     * Tries to initialize a video if we can load it from disk.
+     * @memberof LogoLoader.prototype
+     */
+    _initVideo: function() {
+      var video = document.createElement('video');
+      video.preload = 'auto';
+      video.src = this.videoPath;
+      var self = this;
+      video.onloadeddata = function() {
+        self._onLogoLoaded(video);
+      };
+      video.onerror = function() {
+        self._noVideo = true;
+        if (self._noImage && (typeof self.onnotfound == 'function')) {
+          self.ready = true;
+          self.onnotfound();
+        }
+      };
+    },
+
+    /**
+     * Tries to initialize an image if we can load it from disk.
+     * @memberof LogoLoader.prototype
+     */
+    _initImage: function() {
+      var self = this;
+      var img = new Image();
+      img.src = this.imagePath;
+      img.onload = function() {
+        self._onLogoLoaded(img);
+      };
+      img.onerror = function() {
+        self._noImage = true;
+        if (self._noVideo && (typeof self.onnotfound == 'function')) {
+          self.ready = true;
+          self.onnotfound();
+        }
+      };
+    },
+
+    /**
+     * Called when we have a logo resource ready.
+     * @memberof LogoLoader.prototype
+     * @param {HtmlElement} element An image or video element.
+     */
+    _onLogoLoaded: function(element) {
+      this.found = true;
+      if (!this.ready) {
+        this.ready = true;
+        this.element = element;
+        if (this.onload) {
+          this.onload(element);
+        }
+      }
+    }
+  };
+
+  exports.LogoLoader = LogoLoader;
+
+}(window));