Scott Lanning > Mozilla-DOM > Mozilla::DOM::EventTarget

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NAME ^

Mozilla::DOM::EventTarget

DESCRIPTION ^

Mozilla::DOM::EventTarget is a wrapper around an instance of Mozilla's nsIDOMEventTarget interface. This class inherits from Supports.

 * The nsIDOMEventTarget interface is the interface implemented by all
 * event targets in the Document Object Model.
 *
 * For more information on this interface please see 
 * L<http:E<sol>E<sol>www.w3.orgE<sol>TRE<sol>DOM-Level-2-EventsE<sol>>

Section 1.3 of the DOM Level 2 Events specification says "the EventTarget interface is implemented by all Nodes" and "this interface can be obtained by using binding-specific casting methods on an instance of the Node interface". What this means is you use QueryInterface to transform a Node into an EventTarget. See the documentation below for GetIID.

The AddEventListener and RemoveEventListener methods are only implemented EXPERIMENTALLY. See README for how to enable experimental features.

CLASS METHODS ^

$iid = Mozilla::DOM::EventTarget->GetIID()

Pass this to QueryInterface on a Node object to get back an EventTarget, like

  $iid = Mozilla::DOM::EventTarget->GetIID
  $target = $body->QueryInterface($iid);
  $target->DispatchEvent($event);

You can also print it out, and it will look like

  {1c773b30-d1cf-11d2-bd95-00805f8ae3f4}

METHODS ^

$target->AddEventListener($type, $listener, $useCapture)

THIS METHOD IS EXPERIMENTAL. SEE README FOR HOW TO ENABLE EXPERIMENTAL FEATURES.

This method allows the registration of EventListeners on the event target. If an EventListener is added to an EventTarget while it is processing an Event, it will not be triggered by the current actions but may be triggered during a later stage of event flow, such as the bubbling phase.

If multiple identical EventListeners are registered on the same EventTarget with the same parameters, the duplicate instances are discarded. They do not cause the EventListener to be called twice, and since they are discarded they do not need to be removed with the RemoveEventListener method.

$type

The event type for which the user is registering. This is a string such as 'click'. See Mozilla::DOM::Event::InitEvent for other types.

$listener

The listener parameter takes an interface implemented by the user which contains the methods to be called when the event occurs.

$useCapture

If true, indicates that the user wishes to initiate capture. After initiating capture, all events of the specified type will be dispatched to the registered EventListener before being dispatched to any EventTargets beneath them in the tree. Events which are bubbling upward through the tree will not trigger an EventListener designated to use capture.

$target->RemoveEventListener($type, $listener, $useCapture)

THIS METHOD IS EXPERIMENTAL. SEE README FOR HOW TO ENABLE EXPERIMENTAL FEATURES.

This method allows the removal of event listeners from the event target. If an EventListener is removed from an EventTarget while it is processing an event, it will not be triggered by the current actions. EventListeners can never be invoked after being removed. Calling removeEventListener with arguments which do not identify any currently registered EventListener on the EventTarget has no effect.

$type

Specifies the event type of the EventListener being removed. This is a string such as 'mouseover'. See Mozilla::DOM::Event::InitEvent for the possible types.

$listener

Indicates the EventListener to be removed.

$useCapture

Boolean which specifies whether the EventListener being removed was registered as a capturing listener or not. If a listener was registered twice, one with capture and one without, each must be removed separately. Removal of a capturing listener does not affect a non-capturing version of the same listener, and vice versa.

$bool = $target->DispatchEvent($event)

This method allows the dispatch of an Event into the implementation's event model. Events dispatched in this manner will have the same capturing and bubbling behavior as events dispatched directly by the implementation. The target of the event is the EventTarget on which DispatchEvent is called.

$event

An Event that specifies the event type, behavior, and contextual information to be used in processing the event.

The return value indicates whether any of the listeners which handled the event called PreventDefault. If PreventDefault was called the value is false, else the value is true.

Throws: UNSPECIFIED_EVENT_TYPE_ERR. Raised if the Event's type was not specified by initializing the event before dispatch_event was called. Specification of the Event's type as null or an empty string will also trigger this exception.

SEE ALSO ^

Mozilla::DOM

COPYRIGHT ^

Copyright (C) 2005-2007, Scott Lanning

This software is licensed under the LGPL. See Mozilla::DOM for a full notice.

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