chrome/renderer/resources/extensions/bluetooth_custom_bindings.js

   1 // Copyright (c) 2012 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 // Custom binding for the Bluetooth API.
   6
   7 var binding = require('binding').Binding.create('bluetooth');
   8
   9 var chrome = requireNative('chrome').GetChrome();
  10 var Event = require('event_bindings').Event;
  11 var lastError = require('lastError');
  12 var sendRequest = require('sendRequest').sendRequest;
  13
  14 // Use custom binding to create an undocumented event listener that will
  15 // receive events about device discovery and call the event listener that was
  16 // provided with the request to begin discovery.
  17 binding.registerCustomHook(function(api) {
  18   var apiFunctions = api.apiFunctions;
  19
  20   var bluetooth = {};
  21
  22   function callCallbackIfPresent(name, args, error) {
  23     var callback = args[args.length - 1];
  24     if (typeof(callback) == 'function')
  25       lastError.run(name, error, callback);
  26   }
  27
  28   bluetooth.deviceDiscoveredHandler = null;
  29   bluetooth.onDeviceDiscovered = new Event('bluetooth.onDeviceDiscovered');
  30   function clearDeviceDiscoveredHandler() {
  31     bluetooth.onDeviceDiscovered.removeListener(
  32         bluetooth.deviceDiscoveredHandler);
  33     bluetooth.deviceDiscoveredHandler = null;
  34   }
  35   apiFunctions.setHandleRequest('startDiscovery',
  36       function() {
  37         var args = arguments;
  38         if (args.length > 0 && args[0] && args[0].deviceCallback) {
  39           if (bluetooth.deviceDiscoveredHandler != null) {
  40             callCallbackIfPresent('bluetooth.startDiscovery',
  41                                   args,
  42                                   'Concurrent discovery is not allowed.');
  43             return;
  44           }
  45
  46           bluetooth.deviceDiscoveredHandler = args[0].deviceCallback;
  47           bluetooth.onDeviceDiscovered.addListener(
  48               bluetooth.deviceDiscoveredHandler);
  49           sendRequest(this.name,
  50                       args,
  51                       this.definition.parameters,
  52                       {customCallback:this.customCallback});
  53         } else {
  54           callCallbackIfPresent(
  55             'bluetooth.startDiscovery',
  56             args,
  57             'deviceCallback is required in the options object');
  58           return;
  59         }
  60       });
  61   apiFunctions.setCustomCallback('startDiscovery',
  62       function(name, request, response) {
  63         if (chrome.runtime.lastError) {
  64           clearDeviceDiscoveredHandler();
  65           return;
  66         }
  67       });
  68   apiFunctions.setHandleRequest('stopDiscovery',
  69       function() {
  70         clearDeviceDiscoveredHandler();
  71         sendRequest(this.name, arguments, this.definition.parameters);
  72       });
  73
  74   // An object to hold state during one call to getDevices.
  75   bluetooth.getDevicesState = null;
  76
  77   // Hidden events used to deliver getDevices data to the client callbacks
  78   bluetooth.onDeviceSearchResult = new Event('bluetooth.onDeviceSearchResult');
  79   bluetooth.onDeviceSearchFinished =
  80       new Event('bluetooth.onDeviceSearchFinished');
  81
  82   function deviceSearchResultHandler(device) {
  83     bluetooth.getDevicesState.actualEvents++;
  84     bluetooth.getDevicesState.deviceCallback(device);
  85     maybeFinishDeviceSearch();
  86   }
  87
  88   function deviceSearchFinishedHandler(info) {
  89     bluetooth.getDevicesState.expectedEventCount = info.expectedEventCount;
  90     maybeFinishDeviceSearch();
  91   }
  92
  93   function addDeviceSearchListeners() {
  94     bluetooth.onDeviceSearchResult.addListener(deviceSearchResultHandler);
  95     bluetooth.onDeviceSearchFinished.addListener(deviceSearchFinishedHandler);
  96   }
  97
  98   function removeDeviceSearchListeners() {
  99     bluetooth.onDeviceSearchResult.removeListener(deviceSearchResultHandler);
 100     bluetooth.onDeviceSearchFinished.removeListener(
 101         deviceSearchFinishedHandler);
 102   }
 103
 104   function maybeFinishDeviceSearch() {
 105     var state = bluetooth.getDevicesState;
 106     if (typeof(state.expectedEventCount) != 'undefined' &&
 107         state.actualEvents >= state.expectedEventCount) {
 108       finishDeviceSearch();
 109     }
 110   }
 111
 112   function finishDeviceSearch() {
 113     var finalCallback = bluetooth.getDevicesState.finalCallback;
 114     removeDeviceSearchListeners();
 115     bluetooth.getDevicesState = null;
 116
 117     if (finalCallback) {
 118       finalCallback();
 119     }
 120   }
 121
 122   apiFunctions.setUpdateArgumentsPostValidate('getDevices',
 123       function() {
 124         var args = $Array.slice(arguments);
 125
 126         if (bluetooth.getDevicesState != null) {
 127           throw new Error('Concurrent calls to getDevices are not allowed.');
 128         }
 129
 130         var state = { actualEvents: 0 };
 131
 132         if (typeof(args[args.length - 1]) == 'function') {
 133           state.finalCallback = args.pop();
 134           $Array.push(args,
 135               function() {
 136                 if (chrome.runtime.lastError) {
 137                   finishDeviceSearch();
 138                 }
 139               });
 140         } else {
 141           throw new Error('getDevices must have a final callback parameter.');
 142         }
 143
 144         if (typeof(args[0].deviceCallback) == 'function') {
 145           state.deviceCallback = args[0].deviceCallback;
 146         } else {
 147           throw new Error('getDevices must be passed options with a ' +
 148               'deviceCallback.');
 149         }
 150
 151         bluetooth.getDevicesState = state;
 152         addDeviceSearchListeners();
 153
 154         return args;
 155       });
 156 });
 157
 158 exports.binding = binding.generate();