class EventDispatcher
package openfl.events
implements IEventDispatcher
extended by Icon, NativeApplication, NativeProcess, DisplayObject, DisplayObjectRenderer, FrameLabel, LoaderInfo, NativeWindow, Screen, ShaderJob, Stage3D, TextureBase, Context3D, UncaughtErrorEvents, FileStream, Sound, SoundChannel, DNSResolver, DatagramSocket, FileReference, FileReferenceList, NetConnection, NetStream, ServerSocket, SharedObject, Socket, URLLoader, URLStream, XMLSocket, Accelerometer, StageText, StyleSheet, GameInput, GameInputControl, Timer
Available on all platforms
The EventDispatcher class is the base class for all classes that dispatch events. The EventDispatcher class implements the IEventDispatcher interface and is the base class for the DisplayObject class. The EventDispatcher class allows any object on the display list to be an event target and as such, to use the methods of the IEventDispatcher interface.
Event targets are an important part of the OpenFL event model. The event target serves as the focal point for how events flow through the display list hierarchy. When an event such as a mouse click or a keypress occurs, the OpenFL application dispatches an event object into the event flow fro the root of the display list. The event object then makes its way through the display list until it reaches the event target, at which point it begins its return trip through the display list. This round-trip journey to the event target is conceptually divided into three phases: the capture phase comprises the journey from the root to the last node before the event target's node, the target phase comprises only the event target node, and the bubbling phase comprises any subsequent nodes encountered on the return trip to the root of the display list.
In general, the easiest way for a user-defined class to gain event dispatching capabilities is to extend EventDispatcher. If this is impossible(that is, if the class is already extending another class), you can instead implement the IEventDispatcher interface, create an EventDispatcher member, and write simple hooks to route calls into the aggregated EventDispatcher.
Events:
activate | [broadcast event] Dispatched when the OpenFL application gains operating system focus and becomes active. This event is a broadcast event, which means that it is dispatched by all EventDispatcher objects with a listener registered for this event. For more information about broadcast events, see the DisplayObject class. |
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deactivate | [broadcast event] Dispatched when the OpenFL application loses operating system focus and is becoming inactive. This event is a broadcast event, which means that it is dispatched by all EventDispatcher objects with a listener registered for this event. For more information about broadcast events, see the DisplayObject class. |
See also:
Constructor
new(?target:IEventDispatcher)
Aggregates an instance of the EventDispatcher class.
The EventDispatcher class is generally used as a base class, which means that most developers do not need to use this constructor function. However, advanced developers who are implementing the IEventDispatcher interface need to use this constructor. If you are unable to extend the EventDispatcher class and must instead implement the IEventDispatcher interface, use this constructor to aggregate an instance of the EventDispatcher class.
Parameters:
target | The target object for events dispatched to the EventDispatcher object. This parameter is used when the EventDispatcher instance is aggregated by a class that implements IEventDispatcher; it is necessary so that the containing object can be the target for events. Do not use this parameter in simple cases in which a class extends EventDispatcher. |
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Methods
addEventListener<T>(type:EventType<T>, listener:T ‑> Void, useCapture:Bool = false, priority:Int = 0, useWeakReference:Bool = false):Void
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
removeListener(). Then you can register the listener again
with the new priority level.
Keep in mind that after the listener is registered, subsequent calls to
addEventListener() with a different type or
useCapture value 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.
If you no longer need an event listener, remove it by calling
removeEventListener(), or memory problems could result. Event
listeners are not automatically removed from memory because the garbage
collector does not remove the listener as long as the dispatching object
exists(unless the useWeakReference parameter is set to
true).
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 being processed on this node, the event listener is not triggered during the current phase but can 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 registered again for future processing).
Parameters:
type | The type of event. |
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useCapture | Determines whether the listener works in the
capture phase or the target and bubbling phases.
If |
priority | The priority level of the event listener. The priority is designated by a signed 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. |
useWeakReference | Determines whether the reference to the listener is strong or weak. A strong reference(the default) prevents your listener from being garbage-collected. A weak reference does not. Class-level member functions are not subject to
garbage collection, so you can set
Weak references are supported on some OpenFL targets only, including html5, cpp, and flash/air. On other targets, this parameter is ignored, and the reference will be strong instead. |
Throws:
ArgumentError | The |
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dispatchEvent(event:Event):Bool
Dispatches an event into the event flow. The event target is the
EventDispatcher object upon which the dispatchEvent() method
is called.
Parameters:
event | The Event object that is dispatched into the event flow. If
the event is being redispatched, a clone of the event is
created automatically. After an event is dispatched, its
|
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Returns:
A value of true if the event was successfully
dispatched. A value of false indicates failure or
that preventDefault() was called on the event.
Throws:
Error | The event dispatch recursion limit has been reached. |
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hasEventListener(type:String):Bool
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 actually
triggers an event listener, use 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.
When hasEventListener() is called from a LoaderInfo
object, only the listeners that the caller can access are considered.
Parameters:
type | The type of event. |
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Returns:
A value of true if a listener of the specified type
is registered; false otherwise.
removeEventListener<T>(type:EventType<T>, listener:T ‑> Void, useCapture:Bool = false):Void
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:
type | The type of event. |
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useCapture | 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
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willTrigger(type:String):Bool
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 the hasEventListener() and the
willTrigger() methods is that hasEventListener()
examines only the object to which it belongs, whereas the
willTrigger() method examines the entire event flow for the
event specified by the type parameter.
When willTrigger() is called from a LoaderInfo object,
only the listeners that the caller can access are considered.
Parameters:
type | The type of event. |
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Returns:
A value of true if a listener of the specified type
will be triggered; false otherwise.