---
title: "DecayAnimation"
description: "[DecayAnimation] is an animation that slows down from [initialVelocityVector] as time goes on.
[DecayAnimation] is stateless, and it does not have any concept of lifecycle. It serves as an
animation calculation engine that supports convenient query of value/velocity given a play time.
To achieve that, [DecayAnimation] stores all the animation related information: [initialValue],
[initialVelocityVector], decay animation spec, [typeConverter].

__Note__: Unless there's a need to control the timing manually, it's generally recommended to use
higher level animation APIs that build on top [DecayAnimation], such as
[Animatable.animateDecay], [AnimationState.animateDecay], etc."
type: "class"
---

<div class='type'>Class</div>


<a id='references'></a>

<div class='sourceset sourceset-common'>Common</div>


```kotlin
public class DecayAnimation<T, V : AnimationVector> /*@VisibleForTesting*/
constructor(
    private val animationSpec: VectorizedDecayAnimationSpec<V>,
    override val typeConverter: TwoWayConverter<T, V>,
    public val initialValue: T,
    initialVelocityVector: V,
) : Animation<T, V>
```


`DecayAnimation` is an animation that slows down from `initialVelocityVector` as time goes on.
`DecayAnimation` is stateless, and it does not have any concept of lifecycle. It serves as an
animation calculation engine that supports convenient query of value/velocity given a play time.
To achieve that, `DecayAnimation` stores all the animation related information: `initialValue`,
`initialVelocityVector`, decay animation spec, `typeConverter`.

__Note__: Unless there's a need to control the timing manually, it's generally recommended to use
higher level animation APIs that build on top `DecayAnimation`, such as
`Animatable.animateDecay`, `AnimationState.animateDecay`, etc.


## Secondary Constructors

```kotlin
public constructor(
    animationSpec: DecayAnimationSpec<T>,
    typeConverter: TwoWayConverter<T, V>,
    initialValue: T,
    initialVelocityVector: V,
) : this(
    animationSpec.vectorize(typeConverter),
    typeConverter,
    initialValue,
    initialVelocityVector,
)
```


`DecayAnimation` is an animation that slows down from `initialVelocityVector` as time goes
on. `DecayAnimation` is stateless, and it does not have any concept of lifecycle. It serves
as an animation calculation engine that supports convenient query of value/velocity given a
play time. To achieve that, `DecayAnimation` stores all the animation related information:
`initialValue`, `initialVelocityVector`, decay animation spec, `typeConverter`.

__Note__: Unless there's a need to control the timing manually, it's generally recommended to
use higher level animation APIs that build on top `DecayAnimation`, such as
`Animatable.animateDecay`, `AnimationState.animateDecay`, etc.

#### Parameters

| | |
| --- | --- |
| animationSpec | Decay animation spec that defines the slow-down curve of the animation |
| typeConverter | Type converter to convert the type `T` from and to `AnimationVector` |
| initialValue | The starting value of the animation |
| initialVelocityVector | The starting velocity of the animation in `AnimationVector` form |



```kotlin
public constructor(
    animationSpec: DecayAnimationSpec<T>,
    typeConverter: TwoWayConverter<T, V>,
    initialValue: T,
    initialVelocity: T,
) : this(
    animationSpec.vectorize(typeConverter),
    typeConverter,
    initialValue,
    typeConverter.convertToVector(initialVelocity),
)
```


`DecayAnimation` is an animation that slows down from `initialVelocity` as time goes on.
`DecayAnimation` is stateless, and it does not have any concept of lifecycle. It serves as an
animation calculation engine that supports convenient query of value/velocity given a play
time. To achieve that, `DecayAnimation` stores all the animation related information:
`initialValue`, `initialVelocity`, `animationSpec`, `typeConverter`.

__Note__: Unless there's a need to control the timing manually, it's generally recommended to
use higher level animation APIs that build on top `DecayAnimation`, such as
`Animatable.animateDecay`, `AnimationState.animateDecay`, etc.

#### Parameters

| | |
| --- | --- |
| animationSpec | Decay animation spec that defines the slow-down curve of the animation |
| typeConverter | Type converter to convert the type `T` from and to `AnimationVector` |
| initialValue | The starting value of the animation |
| initialVelocity | The starting velocity of the animation |