Language Version: | ActionScript 3.0 |
Runtime Versions: | Flash Player 9, AIR 1.1 |
| Starting with Flex 4.0, Adobe recommends that you use the spark.effects.animation.Animation class as an alternative to this class.
Tween is the underlying animation class for the effects in Flex 3. As of Flex 4, the Spark
effects use the spark.effects.animation.Animation class to provide similar functionality.
|
The Tween class defines a tween, a property animation performed
on a target object over a period of time.
That animation can be a change in position, such as performed by
the Move effect; a change in size, as performed by the Resize or
Zoom effects; a change in visibility, as performed by the Fade or
Dissolve effects; or other types of animations.
When defining tween effects, you typically create an instance
of the Tween class within your override of the
EffectInstance.play()
method.
A Tween instance accepts the startValue
,
endValue
, and duration
properties,
and an optional easing function to define the animation.
The Tween object invokes the
mx.effects.effectClasses.TweenEffectInstance.onTweenUpdate()
callback function on a regular interval on the effect instance
for the duration of the effect, passing to the
onTweenUpdate()
method an interpolated value
between the startValue
and endValue
.
Typically, the callback function updates some property of the target object,
causing that object to animate over the duration of the effect.
When the effect ends, the Tween objects invokes the
mx.effects.effectClasses.TweenEffectInstance.onTweenEnd()
callback function, if you defined one.
public var duration:Number = 3000
Language Version: | ActionScript 3.0 |
Runtime Versions: | Flash Player 9, AIR 1.1 |
Duration of the animation, in milliseconds.
easingFunction:Function
[write-only]
Language Version: | ActionScript 3.0 |
Runtime Versions: | Flash Player 9, AIR 1.1 |
Sets the easing function for the animation.
The easing function is used to interpolate between
the startValue
value and the endValue
.
A trivial easing function does linear interpolation,
but more sophisticated easing functions create the illusion of
acceleration and deceleration, which makes the animation seem
more natural.
If no easing function is specified, an easing function based
on the Math.sin()
method is used.
The easing function follows the function signature
popularized by Robert Penner.
The function accepts four arguments.
The first argument is the "current time",
where the animation start time is 0.
The second argument is a the initial value
at the beginning of the animation (a Number).
The third argument is the ending value
minus the initial value.
The fourth argument is the duration of the animation.
The return value is the interpolated value for the current time
(usually a value between the initial value and the ending value).
Flex includes a set of easing functions
in the mx.effects.easing package.
Implementation public function set easingFunction(value:Function):void
public var listener:Object
Language Version: | ActionScript 3.0 |
Runtime Versions: | Flash Player 9, AIR 1.1 |
Object that is notified at each interval of the animation.
public function Tween(listener:Object, startValue:Object, endValue:Object, duration:Number = -1, minFps:Number = -1, updateFunction:Function = null, endFunction:Function = null)
Language Version: | ActionScript 3.0 |
Runtime Versions: | Flash Player 9, AIR 1.1 |
Constructor.
When the constructor is called, the animation automatically
starts playing.
Parameters | listener:Object — Object that is notified at each interval
of the animation. You typically pass the this
keyword as the value.
The listener must define the
onTweenUpdate() method and optionally the
onTweenEnd() method.
The former method is invoked for each interval of the animation,
and the latter is invoked just after the animation finishes.
|
|
| startValue:Object — Initial value(s) of the animation.
Either a number or an array of numbers.
If a number is passed, the Tween interpolates
between this number and the number passed
in the endValue parameter.
If an array of numbers is passed,
each number in the array is interpolated.
|
|
| endValue:Object — Final value(s) of the animation.
The type of this argument must match the startValue
parameter.
|
|
| duration:Number (default = -1 ) — Duration of the animation, expressed in milliseconds.
|
|
| minFps:Number (default = -1 ) — Minimum number of times that the
onTweenUpdate() method should be called every second.
The tween code tries to call the onTweenUpdate()
method as frequently as possible (up to 100 times per second).
However, if the frequency falls below minFps ,
the duration of the animation automatically increases.
As a result, an animation that temporarily freezes
(because it is not getting any CPU cycles) begins again
where it left off, instead of suddenly jumping ahead.
|
|
| updateFunction:Function (default = null ) — Specifies an alternative update callback
function to be used instead of listener.OnTweenUpdate()
|
|
| endFunction:Function (default = null ) — Specifies an alternative end callback function
to be used instead of listener.OnTweenEnd()
|
public function endTween():void
Language Version: | ActionScript 3.0 |
Runtime Versions: | Flash Player 9, AIR 1.1 |
Interrupt the tween, jump immediately to the end of the tween,
and invoke the onTweenEnd()
callback function.
public function pause():void
Language Version: | ActionScript 3.0 |
Runtime Versions: | Flash Player 9, AIR 1.1 |
Pauses the effect until you call the resume()
method.
public function resume():void
Language Version: | ActionScript 3.0 |
Runtime Versions: | Flash Player 9, AIR 1.1 |
Resumes the effect after it has been paused
by a call to the pause()
method.
public function reverse():void
Language Version: | ActionScript 3.0 |
Runtime Versions: | Flash Player 9, AIR 1.1 |
Plays the effect in reverse,
starting from the current position of the effect.
public function seek(playheadTime:Number):void
Language Version: | ActionScript 3.0 |
Runtime Versions: | Flash Player 9, AIR 1.1 |
Advances the tween effect to the specified position.
Parameters
| playheadTime:Number — The position, in milliseconds, between 0
and the value of the duration property.
|
public function setTweenHandlers(updateFunction:Function, endFunction:Function):void
Language Version: | ActionScript 3.0 |
Runtime Versions: | Flash Player 9, AIR 1.1 |
By default, the Tween class invokes the
mx.effects.effectClasses.TweenEffectInstance.onTweenUpdate()
callback function on a regular interval on the effect instance
for the duration of the effect, and the optional
mx.effects.effectClasses.TweenEffectInstance.onTweenEnd()
callback function at the end of the effect duration.
This method lets you specify different methods
as the update and the end callback functions.
Parameters
| updateFunction:Function — Specifies the update callback function.
|
|
| endFunction:Function — Specifies the end callback function.
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public function stop():void
Language Version: | ActionScript 3.0 |
Runtime Versions: | Flash Player 9, AIR 1.1 |
Stops the tween, ending it without dispatching an event or calling
the Tween's endFunction or onTweenEnd()
.