chrome/browser/resources/pdf/background.js

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 (function() {
   6   'use strict';
   7
   8   /**
   9    * A map of view ID (which identifies a particular PDF viewer instance) to
  10    * stream object.
  11    * @type {Object.<string, Object>}
  12    */
  13   var streams = {};
  14
  15   /**
  16    * A map of view ID (which identifies a particular PDF viewer instance) to
  17    * initialization function for that view.
  18    * @type {Object.<string, Function>}
  19    */
  20   var pluginInitFunctions = {};
  21
  22   /**
  23    * If we have received a stream object and an initialization function for a
  24    * particular PDF viewer instance we know that the extension has loaded in
  25    * and we can pass it the stream. We can then delete the corresponding map
  26    * entries.
  27    * @param {string} viewId The ID of the view to initialize with a stream.
  28    */
  29   function flush(viewId) {
  30     if (viewId in streams && viewId in pluginInitFunctions) {
  31       pluginInitFunctions[viewId](streams[viewId]);
  32       delete streams[viewId];
  33       delete pluginInitFunctions[viewId];
  34     }
  35   }
  36
  37   /**
  38    * This is called when loading a document with the PDF mime type and passes a
  39    * stream that points to the PDF file. This may be run before or after we
  40    * receive a message from the PDF viewer with its initialization function.
  41    */
  42   chrome.streamsPrivate.onExecuteMimeTypeHandler.addListener(
  43     function(streamDetails) {
  44       // Store the stream until we are contacted by the PDF viewer that owns the
  45       // stream.
  46       streams[streamDetails.viewId] = streamDetails;
  47       flush(streamDetails.viewId);
  48     }
  49   );
  50
  51   /**
  52    * This is called when we receive a message from the PDF viewer indicating
  53    * it has loaded and is ready to receive a stream of the data.
  54    */
  55   chrome.runtime.onMessage.addListener(
  56     function(request, sender, responseFunction) {
  57       // Store the initialization function until we receive the stream which
  58       // corresponds to the PDF viewer.
  59       pluginInitFunctions[request.viewId] = responseFunction;
  60       flush(request.viewId);
  61     }
  62   );
  63 }());