Class: EventDispatcher

var Click = function( name )
{
    this.name = name ;
}

Click.prototype = Object.create( EventListener.prototype ,
{
    constructor : { value : Click } ,
    handleEvent : { value : function( event )
    {
        trace( this + ' ' + this.name + ' event:' + event ) ;
    }}
});

var click1 = new Click( '#1') ;
var click2 = new Click( '#2') ;

// ------

var select = function( event )
{
    trace( "select event:" + event ) ;
};

// ------

var dispatcher = new EventDispatcher() ;

dispatcher.addEventListener( Event.CLICK , click1 ) ;
dispatcher.addEventListener( Event.CLICK , click2 ) ;
dispatcher.addEventListener( Event.CLICK , select , false , 100 ) ;

// ------

dispatcher.dispatchEvent( new Event( Event.CLICK ) ) ;

// ------

dispatcher.removeEventListener( Event.CLICK , click2 ) ;
dispatcher.removeEventListener( Event.CLICK , select ) ;

// ------

dispatcher.dispatchEvent( new Event( Event.CLICK ) ) ;

Methods

---

addEventListener(type, listener [, useCapture] [, priority])

Registers an event listener object with an EventDispatcher object so that the listener receives notification of an event. You can register event listeners on all nodes in the display list for a specific type of event, phase, and priority.

After you successfully register an event listener, you cannot change its priority through additional calls to addEventListener(). To change a listener's priority, you must first call removeEventListener(). Then you can register the listener again with the new priority level.

After the listener is registered, subsequent calls to addEventListener() with a different value for either type or useCapture result in the creation of a separate listener registration. For example, if you first register a listener with useCapture set to true, it listens only during the capture phase. If you call addEventListener() again using the same listener object, but with useCapture set to false, you have two separate listeners: one that listens during the capture phase, and another that listens during the target and bubbling phases.

You cannot register an event listener for only the target phase or the bubbling phase. Those phases are coupled during registration because bubbling applies only to the ancestors of the target node.

When you no longer need an event listener, remove it by calling EventDispatcher.removeEventListener(); otherwise, memory problems might result. Objects with registered event listeners are not automatically removed from memory because the garbage collector does not remove objects that still have references.

Copying an EventDispatcher instance does not copy the event listeners attached to it. (If your newly created node needs an event listener, you must attach the listener after creating the node.) However, if you move an EventDispatcher instance, the event listeners attached to it move along with it.

If the event listener is being registered on a node while an event is also being processed on this node, the event listener is not triggered during the current phase but may be triggered during a later phase in the event flow, such as the bubbling phase.

If an event listener is removed from a node while an event is being processed on the node, it is still triggered by the current actions. After it is removed, the event listener is never invoked again (unless it is registered again for future processing).

Parameters:

Name	Type	Argument	Default	Description
type	string			The type of event.
listener	function | system.events.EventListener			The listener function that processes the event. This function must accept an event object as its only parameter and must return nothing, as this example shows: function(evt) The function can have any name.
useCapture	boolean	<optional>	false	Determines whether the listener works in the capture phase or the target and bubbling phases. If useCapture is set to true, the listener processes the event only during the capture phase and not in the target or bubbling phase. If useCapture is false, the listener processes the event only during the target or bubbling phase. To listen for the event in all three phases, call addEventListener() twice, once with useCapture set to true, then again with useCapture set to false.
priority	number	<optional>	0	The priority level of the event listener. Priorities are designated by a 32-bit integer. The higher the number, the higher the priority. All listeners with priority n are processed before listeners of priority n-1. If two or more listeners share the same priority, they are processed in the order in which they were added. The default priority is 0.

Implements:

• system.events.IEventDispatcher#addEventListener

---

dispatchEvent(event)

Dispatches an event into the event flow. The event target is the EventDispatcher object upon which dispatchEvent() is called.

Parameters:

Name	Type	Description
event	system.event.Event	The event object dispatched into the event flow.

Implements:

• system.events.IEventDispatcher#dispatchEvent

Returns:

A value of true unless preventDefault() is called on the event, in which case it returns false.

---

hasEventListener(type)

Checks whether the EventDispatcher object has any listeners registered for a specific type of event. This allows you to determine where an EventDispatcher object has altered handling of an event type in the event flow hierarchy. To determine whether a specific event type will actually trigger an event listener, use IEventDispatcher.willTrigger().

The difference between hasEventListener() and willTrigger() is that hasEventListener() examines only the object to which it belongs, whereas willTrigger() examines the entire event flow for the event specified by the type parameter.

Parameters:

Name	Type	Description
type	string	The type of event.

Implements:

• system.events.IEventDispatcher#hasEventListener

Returns:

A value of true if a listener of the specified type is registered; false otherwise.

---

removeEventListener(type, listener [, useCapture])

Removes a listener from the EventDispatcher object. If there is no matching listener registered with the EventDispatcher object, a call to this method has no effect.

Parameters:

Name	Type	Argument	Default	Description
type	string			The type of event.
listener	function			listener The listener object to remove.
useCapture	boolean	<optional>	false	Specifies whether the listener was registered for the capture phase or the target and bubbling phases. If the listener was registered for both the capture phase and the target and bubbling phases, two calls to removeEventListener() are required to remove both: one call with useCapture set to true, and another call with useCapture set to false.

Implements:

• system.events.IEventDispatcher#removeEventListener

---

toString()

The string representation of this instance.

Returns:

the string representation of this instance.

---

willTrigger(type)

Checks whether an event listener is registered with this EventDispatcher object or any of its ancestors for the specified event type. This method returns true if an event listener is triggered during any phase of the event flow when an event of the specified type is dispatched to this EventDispatcher object or any of its descendants.

The difference between hasEventListener() and willTrigger() is that hasEventListener() examines only the object to which it belongs, whereas willTrigger() examines the entire event flow for the event specified by the type parameter.

Parameters:

Name	Type	Description
type	string	The type of event.

Implements:

• system.events.IEventDispatcher#willTrigger

Returns:

A value of true if a listener of the specified type will be triggered; false otherwise.