[Animated] some Animated bugs

[magicismight]

Animated is very awesome.but there are some bugs in Animated.

the spring callback won`t be called at once the animation finished.
the callback has something like 200ms delay.

Animated.spring(
 this.state.height,
 {
 toValue: this._height,
 friction: 8,
 tension: 80
 }
).start(callback);

When using Animated.timing and set easing as Easing.back orEasing.elastic.
The element wont animate any more. It just jump to the last frame. Easing.inandEasing.inOut(Easing.ease)` works fine

Animated.timing(
this.state.height,
 {
 toValue: 0,
 easing: Easing.back, // or Easing.elastic
 duration: 200
 }
).start(callback);

[brentvatne]

Hello @magicismight!

1. I believe the issue here is that it takes longer to acquiesce the animation than it appears to - the values may change very gradually as it gets towards the end before settling on the final value.
2. Both back and elastic need to have values passed in that effect the characteristics of the animation - https://github.com/facebook/react-native/blob/e3afc4efd815791e2fc4035f29232ade283e6d8e/Libraries/Animation/Animated/Easing.js#L79-L103 - so if you change your example to easing: Easing.back() or easing: Easing.back(1.5) those will work. Same goes for elastic: easing: Easing.elastic() etc.

If you'd like to update documentation for these to be more clear that could be cool! 😄

[tedjames]

Hey @magicismight and @brentvatne, has anyone made any progress towards fixing that 200ms delay for the callback? It's still an existing issue that to my knowledge, has not yet been addressed.