I have two behaviors of an animation due to Flow setup code, the only difference is how I launch Fl...

# compose

[Mohamed Ibrahim]

I have two behaviors of an animation due to Flow setup code, the only difference is how I launch Flow, code in thread.

[Colton Idle]

@Mohamed Ibrahim can you edit your post to put the code in this thread please?

https://kotlinlang.slack.com/archives/CJLTWPH7S/p1616265877303000

[Mohamed Ibrahim]

sure 😄

[Mohamed Ibrahim]

First setup that generate strange animation , which go and back between the value

flow {
    (0..target).forEach {
        delay(interval)
        emit(it)
    }
}.onEach {
    animateFloat.animateTo(
        targetValue = (it.toFloat() / target) * 360f,
        animationSpec = tween(durationMillis = 1000, easing = FastOutSlowInEasing)
    )
}.launchIn(scope = scope)

----------------

[Mohamed Ibrahim]

Second code that generate the desired animation which animate progress indicator

LaunchedEffect(key1 = animateFloat) {
    flow {
        (0..target).forEach {
            delay(interval)
            emit(it)
        }
    }.collect {
        animateFloat.animateTo(
            targetValue = (it.toFloat() / target) * 360f,
            animationSpec = tween(durationMillis = 1000, easing = FastOutSlowInEasing)
        )
    }
}

I could see that the way I launch Flow is the difference here, but why LaunchedEffect worked and the later didn’t.

[Doris Liu]

The flow in the first snippet gets re-created when recomposed. The new flow gets launched while the previous flow is still emitting.

The second snippet would only recreate the flow when the key to the LaunchedEffect changes. When it does, the previous job will be canceled. So you won't be seeing multiple flows competing to emit new target for the animation.

[Mohamed Ibrahim]

Thank you for the explanation, it make sense