Ticker Class
The Ticker provides a centralized tick or heartbeat broadcast at a set interval. Listeners can subscribe to the tick event to be notified when a set time interval has elapsed.
Note that the interval that the tick event is called is a target interval, and may be broadcast at a slower interval
when under high CPU load. The Ticker class uses a static interface (ex. Ticker.framerate = 30;) and
can not be instantiated.
Example
createjs.Ticker.addEventListener("tick", handleTick);
function handleTick(event) {
// Actions carried out each tick (aka frame)
if (!event.paused) {
// Actions carried out when the Ticker is not paused.
}
}Item Index
Methods
- _dispatchEvent
- _getFPS static
- _getInterval static
- _getTime static
- _handleRAF static
- _handleSynch static
- _handleTimeout static
- _setFPS static
- _setInterval static
- _setupTick static
- _tick static
- addEventListener
- dispatchEvent
- getEventTime static
- getFPS deprecated
- getInterval deprecated
- getMeasuredFPS static
- getMeasuredTickTime static
- getTicks static
- getTime static
- hasEventListener
- init static
- off
- on
- removeAllEventListeners
- removeEventListener
- reset static
- setFPS deprecated
- setInterval deprecated
- toString
- willTrigger
Properties
- _captureListeners
- _inited static
- _interval static
- _lastTime static
- _listeners
- _pausedTicks static
- _pausedTime static
- _raf static
- _startTime static
- _ticks static
- _tickTimes static
- _timerId static
- _times static
- framerate static
- interval static
- maxDelta static
- paused static
- RAF static
- RAF_SYNCHED static
- TIMEOUT static
- timingMode static
Events
Methods
_dispatchEvent
-
eventObj -
eventPhase
_getTime
()
private
static
_handleRAF
()
private
static
_handleSynch
()
private
static
_handleTimeout
()
private
static
_setInterval
-
interval
Use the interval property instead.
Parameters:
-
intervalNumber
_setupTick
()
private
static
_tick
()
private
static
addEventListener
-
type -
listener -
[useCapture]
Adds the specified event listener. Note that adding multiple listeners to the same function will result in multiple callbacks getting fired.
Example
displayObject.addEventListener("click", handleClick);
function handleClick(event) {
// Click happened.
}Parameters:
-
typeStringThe string type of the event.
-
listenerFunction | ObjectAn object with a handleEvent method, or a function that will be called when the event is dispatched.
-
[useCapture]Boolean optionalFor events that bubble, indicates whether to listen for the event in the capture or bubbling/target phase.
dispatchEvent
-
eventObj -
[bubbles] -
[cancelable]
Dispatches the specified event to all listeners.
Example
// Use a string event
this.dispatchEvent("complete");
// Use an Event instance
var event = new createjs.Event("progress");
this.dispatchEvent(event);Parameters:
-
eventObjObject | String | EventAn object with a "type" property, or a string type. While a generic object will work, it is recommended to use a CreateJS Event instance. If a string is used, dispatchEvent will construct an Event instance if necessary with the specified type. This latter approach can be used to avoid event object instantiation for non-bubbling events that may not have any listeners.
-
[bubbles]Boolean optionalSpecifies the
bubblesvalue when a string was passed to eventObj. -
[cancelable]Boolean optionalSpecifies the
cancelablevalue when a string was passed to eventObj.
Returns:
Returns false if preventDefault() was called on a cancelable event, true otherwise.
getEventTime
-
runTime
Parameters:
-
runTimeBoolean[runTime=false] If true, the runTime property will be returned instead of time.
Returns:
The time or runTime property from the most recent tick event or -1.
getMeasuredFPS
-
[ticks]
Returns the actual frames / ticks per second.
Parameters:
-
[ticks]Number optionalThe number of previous ticks over which to measure the actual frames / ticks per second. Defaults to the number of ticks per second.
Returns:
The actual frames / ticks per second. Depending on performance, this may differ from the target frames per second.
getMeasuredTickTime
-
[ticks]
Returns the average time spent within a tick. This can vary significantly from the value provided by getMeasuredFPS because it only measures the time spent within the tick execution stack.
Example 1: With a target FPS of 20, getMeasuredFPS() returns 20fps, which indicates an average of 50ms between the end of one tick and the end of the next. However, getMeasuredTickTime() returns 15ms. This indicates that there may be up to 35ms of "idle" time between the end of one tick and the start of the next.
Example 2: With a target FPS of 30, framerate returns 10fps, which indicates an average of 100ms between the end of one tick and the end of the next. However, getMeasuredTickTime returns 20ms. This would indicate that something other than the tick is using ~80ms (another script, DOM rendering, etc).
Parameters:
-
[ticks]Number optionalThe number of previous ticks over which to measure the average time spent in a tick. Defaults to the number of ticks per second. To get only the last tick's time, pass in 1.
Returns:
The average time spent in a tick in milliseconds.
getTicks
-
pauseable
Returns the number of ticks that have been broadcast by Ticker.
Parameters:
-
pauseableBooleanIndicates whether to include ticks that would have been broadcast while Ticker was paused. If true only tick events broadcast while Ticker is not paused will be returned. If false, tick events that would have been broadcast while Ticker was paused will be included in the return value. The default value is false.
Returns:
of ticks that have been broadcast.
getTime
-
[runTime=false]
Returns the number of milliseconds that have elapsed since Ticker was initialized via {{#crossLink "Ticker/init"}}. Returns -1 if Ticker has not been initialized. For example, you could use this in a time synchronized animation to determine the exact amount of time that has elapsed.
Parameters:
-
[runTime=false]Boolean optionalIf true only time elapsed while Ticker was not paused will be returned. If false, the value returned will be total time elapsed since the first tick event listener was added.
Returns:
Number of milliseconds that have elapsed since Ticker was initialized or -1.
hasEventListener
-
type
Indicates whether there is at least one listener for the specified event type.
Parameters:
-
typeStringThe string type of the event.
Returns:
Returns true if there is at least one listener for the specified event.
init
()
static
Starts the tick. This is called automatically when the first listener is added.
off
-
type -
listener -
[useCapture]
A shortcut to the removeEventListener method, with the same parameters and return value. This is a companion to the .on method.
IMPORTANT: To remove a listener added with on, you must pass in the returned wrapper function as the listener. See
on for an example.
on
-
type -
listener -
[scope] -
[once=false] -
[data] -
[useCapture=false]
A shortcut method for using addEventListener that makes it easier to specify an execution scope, have a listener only run once, associate arbitrary data with the listener, and remove the listener.
This method works by creating an anonymous wrapper function and subscribing it with addEventListener.
The wrapper function is returned for use with removeEventListener (or off).
IMPORTANT: To remove a listener added with on, you must pass in the returned wrapper function as the listener, or use
remove. Likewise, each time you call on a NEW wrapper function is subscribed, so multiple calls
to on with the same params will create multiple listeners.
Example
var listener = myBtn.on("click", handleClick, null, false, {count:3});
function handleClick(evt, data) {
data.count -= 1;
console.log(this == myBtn); // true - scope defaults to the dispatcher
if (data.count == 0) {
alert("clicked 3 times!");
myBtn.off("click", listener);
// alternately: evt.remove();
}
}Parameters:
-
typeStringThe string type of the event.
-
listenerFunction | ObjectAn object with a handleEvent method, or a function that will be called when the event is dispatched.
-
[scope]Object optionalThe scope to execute the listener in. Defaults to the dispatcher/currentTarget for function listeners, and to the listener itself for object listeners (ie. using handleEvent).
-
[once=false]Boolean optionalIf true, the listener will remove itself after the first time it is triggered.
-
[data]optionalArbitrary data that will be included as the second parameter when the listener is called.
-
[useCapture=false]Boolean optionalFor events that bubble, indicates whether to listen for the event in the capture or bubbling/target phase.
Returns:
Returns the anonymous function that was created and assigned as the listener. This is needed to remove the listener later using .removeEventListener.
removeAllEventListeners
-
[type]
Removes all listeners for the specified type, or all listeners of all types.
Example
// Remove all listeners
displayObject.removeAllEventListeners();
// Remove all click listeners
displayObject.removeAllEventListeners("click");Parameters:
-
[type]String optionalThe string type of the event. If omitted, all listeners for all types will be removed.
removeEventListener
-
type -
listener -
[useCapture]
Removes the specified event listener.
Important Note: that you must pass the exact function reference used when the event was added. If a proxy function, or function closure is used as the callback, the proxy/closure reference must be used - a new proxy or closure will not work.
Example
displayObject.removeEventListener("click", handleClick);reset
()
static
Stops the Ticker and removes all listeners. Use init() to restart the Ticker.
willTrigger
-
type
Indicates whether there is at least one listener for the specified event type on this object or any of its ancestors (parent, parent's parent, etc). A return value of true indicates that if a bubbling event of the specified type is dispatched from this object, it will trigger at least one listener.
This is similar to hasEventListener, but it searches the entire event flow for a listener, not just this object.
Parameters:
-
typeStringThe string type of the event.
Returns:
Returns true if there is at least one listener for the specified event.
Properties
_pausedTicks
Number
private
static
The number of ticks that have passed while Ticker has been paused
_raf
Boolean
private
static
True if currently using requestAnimationFrame, false if using setTimeout. This may be different than timingMode if that property changed and a tick hasn't fired.
framerate
Number
static
Indicates the target frame rate in frames per second (FPS). Effectively just a shortcut to interval, where
framerate == 1000/interval.
interval
Number
static
Indicates the target time (in milliseconds) between ticks. Default is 50 (20 FPS).
Note that actual time between ticks may be more than specified depending on CPU load.
This property is ignored if the ticker is using the RAF timing mode.
maxDelta
Number
static
Specifies a maximum value for the delta property in the tick event object. This is useful when building time based animations and systems to prevent issues caused by large time gaps caused by background tabs, system sleep, alert dialogs, or other blocking routines. Double the expected frame duration is often an effective value (ex. maxDelta=50 when running at 40fps).
This does not impact any other values (ex. time, runTime, etc), so you may experience issues if you enable maxDelta when using both delta and other values.
If 0, there is no maximum.
Default: 0
paused
Boolean
static
When the ticker is paused, all listeners will still receive a tick event, but the paused property
of the event will be true. Also, while paused the runTime will not increase. See tick,
getTime, and getEventTime for more
info.
Example
createjs.Ticker.addEventListener("tick", handleTick);
createjs.Ticker.paused = true;
function handleTick(event) {
console.log(event.paused,
createjs.Ticker.getTime(false),
createjs.Ticker.getTime(true));
}Default: false
RAF
String
static
readonly
In this mode, Ticker passes through the requestAnimationFrame heartbeat, ignoring the target framerate completely. Because requestAnimationFrame frequency is not deterministic, any content using this mode should be time based. You can leverage getTime and the tick event object's "delta" properties to make this easier.
Falls back on TIMEOUT if the requestAnimationFrame API is not supported.
Default: "raf"
RAF_SYNCHED
String
static
readonly
In this mode, Ticker uses the requestAnimationFrame API, but attempts to synch the ticks to target framerate. It uses a simple heuristic that compares the time of the RAF return to the target time for the current frame and dispatches the tick when the time is within a certain threshold.
This mode has a higher variance for time between frames than TIMEOUT, but does not require that content be time based as with RAF while gaining the benefits of that API (screen synch, background throttling).
Variance is usually lowest for framerates that are a divisor of the RAF frequency. This is usually 60, so framerates of 10, 12, 15, 20, and 30 work well.
Falls back to TIMEOUT if the requestAnimationFrame API is not supported.
Default: "synched"
TIMEOUT
String
static
readonly
In this mode, Ticker uses the setTimeout API. This provides predictable, adaptive frame timing, but does not provide the benefits of requestAnimationFrame (screen synch, background throttling).
Default: "timeout"
timingMode
String
static
Specifies the timing api (setTimeout or requestAnimationFrame) and mode to use. See TIMEOUT, RAF, and RAF_SYNCHED for mode details.
Default: Ticker.TIMEOUT
Events
tick
Dispatched each tick. The event will be dispatched to each listener even when the Ticker has been paused using paused.
Example
createjs.Ticker.addEventListener("tick", handleTick);
function handleTick(event) {
console.log("Paused:", event.paused, event.delta);
}Event Payload:
-
targetObjectThe object that dispatched the event.
-
typeStringThe event type.
-
pausedBooleanIndicates whether the ticker is currently paused.
-
deltaNumberThe time elapsed in ms since the last tick.
-
timeNumberThe total time in ms since Ticker was initialized.
-
runTimeNumberThe total time in ms that Ticker was not paused since it was initialized. For example, you could determine the amount of time that the Ticker has been paused since initialization with
time-runTime.