Wirestorm

Following on from yesterday, I needed to pass arguments to the window being opened. The data I needed to pass was quite simple, so I simply serialized it to JSON and then passed them as strings in a nsICollection (actually, a @mozilla.org/supports-array;1 collection of @mozilla.org/supports-string;1) and then just eval()’d the data within the xul window’s javascript.

This is a bit of a hack, but its probably the simplest way of passing structured data. What would be nice is a bit of code that would automagically serialize a bean to JSON notation… I’m sure there are many out there (This apache struts class looks promising)

Finally worked this out…

These pages are rather helpful: Mozilla’s guide to using proxies and XulPlanet’s description of the nsIProxyObjectManager

This interface defines a proxy manager. An instance of this manager is used to create a proxy for a particular object on which you wish to invoke a method. If you are calling from any other thread that which you initialized xpcom on, you will need to do this, and as far as I am aware, there is no trivial way of doing otherwise.

Anyway, the code to open a new window would be as follows. Note, this method assumes that there is already a constructed object called windowWatcher, which is an instanceof nsIWindowWatcher, see previous post for details.

 public void openWindow(String chromeUri, String name) {
nsIEventQueueService eventQueueServive =
(nsIEventQueueService)serviceManager.getServiceByContractID(
"@mozilla.org/event-queue-service;1",
nsIEventQueueService.NS_IEVENTQUEUESERVICE_IID);

nsIEventQueue eventQueue = eventQueueServive.getSpecialEventQueue(
nsIEventQueueService.UI_THREAD_EVENT_QUEUE);

nsIProxyObjectManager proxy =
(nsIProxyObjectManager)componentManager.createInstanceByContractID(
"@mozilla.org/xpcomproxy;1",
null,
nsIProxyObjectManager.NS_IPROXYOBJECTMANAGER_IID);

nsIWindowWatcher windowProxy =
(nsIWindowWatcher)proxy.getProxyForObject(
eventQueue,
windowWatcher.NS_IWINDOWWATCHER_IID,
windowWatcher,
nsIProxyObjectManager.INVOKE_SYNC );

windowProxy.openWindow(null, chromeUri, name, "centerscreen", null);
} 

The code here uses the service manager to get an instance of the event queue manager, which is subsequently used to retreive the main UI event queue. This is then passed to the proxy manager’s getProxyForObject method, along with the IID of the nsIWindowWatcher interface, the actual instance, and flag representing the type of proxy operation (async, sync, etc, see the xulplanet page for more info).

This method returns an instance of nsIWindowWatcher, which is actually a proxy which will inject events onto the UI thread for you. Then, just use the object as normal, sweet!