tween-base


This is a base class for tween types, built alongside tweenr and tween-ticker. It is not inherently tied to those modules, and may prove useful outside of those environments.

Usually you won't require tween-base itself, but the modules that build on top of it. Example:

``js
var array = require('tween-array')
var ticker = require('tween-ticker')

var start = [25, 15],
end = [10, 10]

ticker.push(array(start, end, { duration: 2 }))
.on('complete', function(ev) {
console.log("result:", ev.target)
})
`

Usage

![NPM](https://nodei.co/npm/tween-base/)

This describes the public (user-facing) API for tweens.

#### tween = BaseTween(opt)

Where options usually describes the following:

- delay in time units, default 0
- duration in time units, default 0
- ease is an easing function -- tween engines may want to allow strings for user friendliness

methods

#### cancel()

Cancels a tween. Returns this for chaining. Next time this tween is ticked, it will:

- emit a "cancelling" event
- become inactive and stop updating the target
- emit a "complete" event

A ticker engine might then choose to remove the tween from the queue.

members

#### tween.on(event, func)

A tween is an event emitter with the following events:

- start triggered when the tween is first started
- cancelling triggered before the tween completes, initiating from a call to cancel()
- complete triggered when the tween is completed
- update triggered after the tween updates its values

--

inheriting

See test/array.js for an example of a custom array interpolation.

Implementors might subclass like so:

`js
var Base = require('tween-base')
var inherits = require('inherits')

function MyTween(target, opt) {
Base.call(this, opt)
this.target = target
}

inherits(MyTween, Base)

//called before 'start' event
MyTween.prototype.ready = function() {
//this is where you might store the current
//state of "target" so that you can interpolate
//from start to end
}

MyTween.prototype.lerp = function(alpha) {
//interpolate "target" from start to end using alpha
}
``

License

MIT, see LICENSE.md for details.