I need something like a finish listener when using...

# compose

[Mehdi Haghgoo]

I need something like a finish listener when using Transition.AnimatedVisibility(), but I don't find any in the API.
For example, how can I fade out a heart that has been faded in with previous transition?

[Doris Liu]

In the spirit of making Transition declarative, we don't have a finish listener for it. But whether the animation has been finished can be derived from Transition.currentState == Transition.targetState .

You could: 1) Use MutableTransitionState to create the Transition/AnimatedVisibility, and change the MutableTransitionState#targetState when MutableTransitionState.isIdle .
or 2) Create a snapshotFlow of the Transition.currentState to get the event when the state changes.

If you are only trying to fade in & out a heart repeatedly, a repeatable animation in an InfiniteTransition or Transition may be a better choice.

[Mehdi Haghgoo]

Sounds pretty complicated 🙂 😅

[Doris Liu]

Are you just trying to get the heart fade in and out repeatedly?

[Mehdi Haghgoo]

No, just making it fade in and stay for a second and fade out, something like an instagram animation that happens when the user double taps a picture.

[Doris Liu]

Coincidentally, we have a demo for almost exactly that: https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:compose/[…]idx/compose/animation/core/samples/TransitionSamples.kt;l=243

[Mehdi Haghgoo]

Oh, that's nice. Thank 😊you @Doris Liu 🙏