gecko/mobile/android/modules/OrderedBroadcast.jsm

81 lines
2.5 KiB
JavaScript

// -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
"use strict";
this.EXPORTED_SYMBOLS = ["sendOrderedBroadcast"];
const { classes: Cc, interfaces: Ci, utils: Cu } = Components;
// For adding observers.
Cu.import("resource://gre/modules/Services.jsm");
Cu.import("resource://gre/modules/Messaging.jsm");
let _callbackId = 1;
/**
* Send an ordered broadcast to Java.
*
* Internally calls Context.sendOrderedBroadcast.
*
* action {String} should be a string with a qualified name (like
* org.mozilla.gecko.action) that will be broadcast.
*
* token {Object} is a piece of arbitrary data that will be given as
* a parameter to the callback (possibly null).
*
* callback {function} should accept three arguments: the data
* returned from Java as an Object; the specified token; and the
* specified action.
*
* permission {String} is an optional string with an Android permission
* that packages must have to respond to the ordered broadcast. A null
* value allows any package to respond. If the parameter is omitted (or
* {undefined}), then the intent is restricted to the current package.
*/
function sendOrderedBroadcast(action, token, callback, permission) {
let callbackId = _callbackId++;
let responseEvent = "OrderedBroadcast:Response:" + callbackId;
let observer = {
callbackId: callbackId,
callback: callback,
observe: function observe(subject, topic, data) {
if (topic != responseEvent) {
return;
}
// Unregister observer as soon as possible.
Services.obs.removeObserver(observer, responseEvent);
let msg = JSON.parse(data);
if (!msg.action || !msg.token || !msg.token.callbackId)
return;
let theToken = msg.token.data;
let theAction = msg.action;
let theData = msg.data ? JSON.parse(msg.data) : null;
let theCallback = this.callback;
if (!theCallback)
return;
// This is called from within a notified observer, so we don't
// need to take special pains to catch exceptions.
theCallback(theData, theToken, theAction);
},
};
Services.obs.addObserver(observer, responseEvent, false);
Messaging.sendRequest({
type: "OrderedBroadcast:Send",
action: action,
responseEvent: responseEvent,
token: { callbackId: callbackId, data: token || null },
permission: permission,
});
};