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Animator - Javascript

Copyright (c) 2012 Erik Landvall

Dual licensed under the MIT and GPL version 3 licenses.

What's this

Animator is ment to create smother animations when possible. It uses requestAnimationFrame as callback routine. It also has an queue system to prevent multiple simultaneous routines being used at the same time.


If you have any questions you're more then welcome to contact me on twitter: ErikLandvall, or just add an issue here on github and I will answer as fast as I can.


Example of use

Let's start of by defining our rendering loop:

var loop = function()
  // do cool stuff

Then we need an instance of Animator:
The new interface has a static alternative that doesn't require this step

var instance = new Animator();

Now we want to add the loop to Animators queue:

var id = instance.addCallback( loop );

// Or you can use a shorter alternative:
var id = instance.add( loop );

// And then there is a static alternative:
var id = Animator.add( loop );

By adding the loop to a queue we are able to use multiple rendering loops within the same callback routin. Just stack them on by using addCallback

By adding a callback to the routine we also start the animation. If we wish to prevent this to manually start the routine at a later point we have to declare this when calling the method. We do this by passing on a false third parameter to the method:

var id = instance.add( loop, null, false );

// Static alternative:
var id = Animator.add( loop, null, false );

To start the routine manually:


// Static alternative:

To stop Animator from calling the loop we need to remove it from the queue, we can do this manually or specify how many times the loop should be called upon adding it to the queue.

To do it manually we need to alter the rendering loop:

var loop = function( i )
  if( i == expectedLength )
    instance.removeCallback( id );

    // Or a more simple alternative:
    instance.remove( id );

    // Static alternative:
    Animator.remove( id );


  // do cool stuff

Tough, if we alredy know the expected length then we can specify this when we add the loop to the queue:

instance.add( loop, expectedLength );

// Static alternative:
Animator.add( loop, expectedLength );

By specifying the expected length when we add the loop to the queue we no longer need to alter the animation loop.

When there's no longer any callbacks in the queue then the routine will automatically stop. If you by any reason would like to stop or pause the routine at any time then use the method stop:


// Static alternative:

Animators instance interface

Name Return type Parameters Description
start Animator Starts the animation loop, if not already running.
stop Animator Stops/Pauses the animation loop, if running.
isRunning boolean Returns if animation loop is currently running.
getCallback function|null int|string id
The id of the callback we wont returned
Returns the callback by specified id. If id dosn't exists in queue, null is returned
get Alias for "getCallback" and "getQueue". If param is undefined then the whole queue is returned.
setCallback Animator int|string id
The id of the callback

function fn
The callback we wish to set

int length [optional]
How many times we wish to call upon the callback
Sets a callback function with a given id. This can also be used to replace an alredy existing callback.

WARNING! Using this function is not the recomended way to add a function to the queue. Use addCallback for this purpose instead.
set Alias for "setCallback" and "setQueue".
addCallback int|array function|array fn
The function, or an array of functions, we wish to add to the queue

int length [optional]
How many times we wish to call upon the callback

start boolean [optional]
If true, the callback routine will automatically start after callbacks are added. Defaults to true
Adds one or many functions to the queue. Returns the generated id or an array of them if multiple callbacks where specicified.
add Alias for "addCallback"
removeCallback Animator int|function|object fn
The id, function or instance we wish to remove from the queue
Removes a callback from the queue and stops the routine if there's no more callbacks in the queue.
remove Alias for "removeCallback"
getQueue Object Returns the current queue
setQueue Animator Object queue
The queue new queue
Clears the old queue and sets a new one.
clearQueue Animator Unsets the queue
clear Alias for "clearQueue"
isQueueEmpty boolean Returns if the queue is empty.
getElement Element|undefined Returns the specified element we wish to render on.
setElement Animator Element element
The element to render in
Not required! If specifyed one may optimize the animation.
removeElement Animator Removes any specified element to render in.

Animators static interface

OBS! All the methods that are availible from the instance interface are also availible in the static interface.

Name Return type Parameters Description
getInstance Animator Lazyloads an instance that can be acceced through a static interface.
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