How I can trigger a piece of code only in the initial composition inside a function?

# compose

[AmrJyniat]

How I can trigger a piece of code only in the initial composition inside a function?

[darkmoon_uk]

LaunchedEffect(key = null) {
    // First time only stuff
}

[AmrJyniat]

I need to trigger the code inside offset lambda in modifier like this:

Modifier.offset {
//{Trigger code in the initial composition only}
IntOffset(offsetTransitionActions.roundToInt(), 0)
}

LaunchedEffect{} need a composable scope which is not exists in offset lambda.

[darkmoon_uk]

Well in that case, call me old fashioned but you could simply use an isFirstTime flag? Composition is single threaded so it should be safe (for now).

[Felix Schütz]

If you want to animate the offset, there are helpers for that (animating a value from start to target on initial composition).

[AmrJyniat]

I have offsetTransitionActions to animate the offsite but it depends on another value that takes some mills to calculate.
so I want to set a value to the offset modifier while the calculation gets ready.

[Zach Klippenstein (he/him) [MOD]]

Don't rely on composition being single-threaded, that could eventually change

[Zach Klippenstein (he/him) [MOD]]

I think the offset lambda is probably the wrong place for logic like this. The only reason that is a lambda is so you can do state reads without triggering recomposition.

[AmrJyniat]

Well, how to do this logic in your opinion?

[Zach Klippenstein (he/him) [MOD]]

Can you elaborate what you're actually trying to do?

[AmrJyniat]

I want to implement "Swipe to show buttons" feature to my card as the following:
  -- Box
      -- Card
      -- Row(here I put the buttons which showing when swipe the card)

Now the card and row are visible next to each other so I want to offset the row to be invisible in the normal look and return it to 0 offsets(visible) when the user swipes the card.

when observing user's swipe on the card I do the following:
• Change the card's offset based on the Row's width to the left via animateFloat like this:

val offsetTransitionCard by transition.animateFloat(
    targetValueByState = { if (isRevealed) -rowWidth else 0f },
)

• Change the row's offset to 0 via animateFloat like this:

val offsetTransitionRow by transitionActions.animateFloat(
    targetValueByState = { if (isRevealed) 0f else rowWidth },
)

till now all good but we have one problem, when initial composition occurred the rowWidth will be 0 because it's not calculated yet which means the Row offset will be 0 too which means again the Row will be showing for mills then will offset when the rowWidth gets ready.

So I want a way to make the row's default offset to be like 500 instead of 0 on the initial compose only.

[AmrJyniat]

Video clips feature is more than awesome!

Screenshare - 2021-09-30 12:16:28 PM.webm