Registers a message listener.
<static> addMessageListener( filters, MessageListener, [containingObject] )
| Name | Type | Argument | Description |
| filters | hwc.MessageFilter | The message filter that message events must pass to get passed to the anonymous.MessageListener. If no filter is desired, then null can be used for this parameter. | |
| MessageListener | anonymous.MessageListener | The callback function for message changes. | |
| containingObject | Object | (optional) | The containing object of the message listener.If a message listener callback function references variables in its containing object, then the containing object should be passed to this function. |
// soSomething is a global function called by the listener callback.
var doSomething = function()
{
alert("New message!");
}
// messageListener is the callback function passed to hwc.addMessageListener.
var messageListener = function( flag, messageId )
{
if( flag == hwc.MSG_ADDED )
{
doSomething();
}
}
// We do not want to filter the message events the listener will get invoked for, so pass null for the first parameter.
hwc.addMessageListener( null, messageListener );
// someObject is an object that will contain the listener callback as well as a variable referenced by the callback.
var someObject = {};
// doSomething is a function referenced by the callback function.
someObject.doSomething = function()
{
alert("New message!");
}
// messageListener is the callback that will be passed to hwc.addMessageListener.
someObject.messageListener = function( flag, messageId )
{
if( flag == hwc.MSG_ADDED )
{
this.doSomething();
}
}
// Create a filter so that not all message events will invoke our callback function.
// Only events about messages with a subject of "Subject" will trigger our callback function.
var filter = new hwc.MessageFilter( null, "Subject", null, null, null, null);
// The callback function references a variable in its containing object, so we need to pass in the containing object
// in addition to the filter and the callback function.
hwc.addMessageListener( filter, someObject.messageListener, someObject );