Phaser CE Class: Signal

new Signal()

Signals are what Phaser uses to handle events and event dispatching. You can listen for a Signal by binding a callback / function to it. This is done by using either Signal.add or Signal.addOnce.

For example you can listen for a touch or click event from the Input Manager by using its onDown Signal:

game.input.onDown.add(function() { ... });

Rather than inline your function, you can pass a reference:

game.input.onDown.add(clicked, this); function clicked () { ... }

In this case the second argument (this) is the context in which your function should be called.

Now every time the InputManager dispatches the onDown signal (or event), your function will be called.

Multiple callbacks can be bound to the same signal. They're ordered first by their priority arguments and then by the order in which they were added. If a callback calls halt or returns false, any remaining callbacks are skipped.

Very often a Signal will send arguments to your function. This is specific to the Signal itself. If you're unsure then check the documentation, or failing that simply do:

Signal.add(function() { console.log(arguments); })

and it will log all of the arguments your function received from the Signal.

Sprites have lots of default signals you can listen to in their Events class, such as:

sprite.events.onKilled

Which is called automatically whenever the Sprite is killed. There are lots of other events, see the Events component for a list.

As well as listening to pre-defined Signals you can also create your own:

var mySignal = new Phaser.Signal();

This creates a new Signal. You can bind a callback to it:

mySignal.add(myCallback, this);

and then finally when ready you can dispatch the Signal:

mySignal.dispatch(your arguments);

And your callback will be invoked. See the dispatch method for more details.

Source:: src/core/Signal.js line 64

Members

active : boolean

Is the Signal active? Only active signals will broadcast dispatched events.

Setting this property during a dispatch will only affect the next dispatch. To stop the propagation of a signal from a listener use halt.

Type:

boolean

Default Value:

true

Source:

src/core/Signal.js line 104

memorize : boolean

Memorize the previously dispatched event?

If an event has been memorized it is automatically dispatched when a new listener is added with add or addOnce. Use forget to clear any currently memorized event.

Type:

boolean

Source:: src/core/Signal.js line 88

Methods

add(listener [, listenerContext] [, priority] [, args])

Add an event listener for this signal.

An event listener is a callback with a related context and priority.

You can optionally provide extra arguments which will be passed to the callback after any internal parameters.

For example: Phaser.Key.onDown when dispatched will send the Phaser.Key object that caused the signal as the first parameter. Any arguments you've specified after priority will be sent as well:

fireButton.onDown.add(shoot, this, 0, 'lazer', 100);

When onDown dispatches it will call the shoot callback passing it: Phaser.Key, 'lazer', 100.

Where the first parameter is the one that Key.onDown dispatches internally and 'lazer', and the value 100 were the custom arguments given in the call to 'add'.

If the callback calls halt or returns false, any remaining callbacks bound to this Signal are skipped.

Parameters:

Name	Type	Argument	Default	Description
`listener`	function			The function to call when this Signal is dispatched.
`listenerContext`	object	<optional>		The context under which the listener will be executed (i.e. the object that should represent the `this` variable).
`priority`	number	<optional>		The priority level of the event listener. Listeners with higher priority will be executed before listeners with lower priority. Listeners with same priority level will be executed at the same order as they were added (default = 0)
`args`	any	<optional> <repeatable>	(none)	Additional arguments to pass to the callback (listener) function. They will be appended after any arguments usually dispatched.

Source:: src/core/Signal.js line 232

Returns:

An Object representing the binding between the Signal and listener.

Type: Phaser.SignalBinding

addOnce(listener [, listenerContext] [, priority] [, args])

Add a one-time listener - the listener is automatically removed after the first execution.

If there is as memorized event then it will be dispatched and the listener will be removed immediately.

Parameters:

Name	Type	Argument	Default	Description
`listener`	function			The function to call when this Signal is dispatched.
`listenerContext`	object	<optional>		The context under which the listener will be executed (i.e. the object that should represent the `this` variable).
`priority`	number	<optional>		The priority level of the event listener. Listeners with higher priority will be executed before listeners with lower priority. Listeners with same priority level will be executed at the same order as they were added (default = 0)
`args`	any	<optional> <repeatable>	(none)	Additional arguments to pass to the callback (listener) function. They will be appended after any arguments usually dispatched.

Source:: src/core/Signal.js line 275

Returns:

An Object representing the binding between the Signal and listener.

Type: Phaser.SignalBinding

dispatch( [params])

Dispatch / broadcast the event to all listeners.

To create an instance-bound dispatch for this Signal, use boundDispatch.

Parameters:

Name	Type	Argument	Description
`params`	any	<optional>	Parameters that should be passed to each handler.

Source:: src/core/Signal.js line 391

dispose()

Dispose the signal - no more events can be dispatched.

This removes all event listeners and clears references to external objects. Calling methods on a disposed objects results in undefined behavior.

Source:: src/core/Signal.js line 448

forget()

Forget the currently memorized event, if any.

Source:: src/core/Signal.js line 435

getNumListeners()

Gets the total number of listeners attached to this Signal.

Source:: src/core/Signal.js line 367

Returns:

Number of listeners attached to the Signal.

Type: integer

halt()

Stop propagation of the event, blocking the dispatch to next listener on the queue.

This should be called only during event dispatch as calling it before/after dispatch won't affect another broadcast. See active to enable/disable the signal entirely.

Source:: src/core/Signal.js line 378

has(listener [, context])

Check if a specific listener is attached.

Parameters:

Name	Type	Argument	Description
`listener`	function		Signal handler function.
`context`	object	<optional>	Context on which listener will be executed (object that should represent the `this` variable inside listener function).

Source:: src/core/Signal.js line 219

Returns:

If Signal has the specified listener.

Type: boolean

remove(listener [, context])

Remove a single event listener.

Parameters:

Name	Type	Argument	Default	Description
`listener`	function			Handler function that should be removed.
`context`	object	<optional>	null	Execution context (since you can add the same handler multiple times if executing in a different context).

Source:: src/core/Signal.js line 305

Returns:

Listener handler function.

Type: function

removeAll( [context])

Remove all event listeners.

Parameters:

Name	Type	Argument	Default	Description
`context`	object	<optional>	null	If specified only listeners for the given context will be removed.

Source:: src/core/Signal.js line 328

toString()

A string representation of the object.

Source:: src/core/Signal.js line 467

Returns:

String representation of the object.

Type: string