Should I use remember with animateDpAsState?

Issue

The Code A is from the official sample code here.

I know that in order to preserve state across recompositions, remember the mutable state using remember.

I think that the code val extraPadding by animateDpAsState(...) should be val extraPadding by remember { animateDpAsState(...) }, is it right?

BTW, val extraPadding by remember { animateDpAsState(...) } will cause the error

Composable calls are not allowed inside the calculation parameter of inline fun remember(calculation: () -> TypeVariable(T)): TypeVariable(T)

Code A

@Composable
private fun Greeting(name: String) {

    var expanded by remember { mutableStateOf(false) }

    val extraPadding by animateDpAsState(                  //Should I add remember
        if (expanded) 48.dp else 0.dp
    ) 

    Surface(
        color = MaterialTheme.colors.primary,
        modifier = Modifier.padding(vertical = 4.dp, horizontal = 8.dp)
    ) {
        Row(modifier = Modifier.padding(24.dp)) {
            Column(modifier = Modifier
                .weight(1f)
                .padding(bottom = extraPadding)
            ) {
                Text(text = "Hello, ")
                Text(text = name)
            }
            OutlinedButton(
                onClick = { expanded = !expanded }
            ) {
                Text(if (expanded) "Show less" else "Show more")
            }

        }
    }
}

Solution

No, you shouldn't. This function is marked with @Composable so it should be used directly in the view builder.

animateDpAsState will calculate its value depending on targetValue on each recomposition.

If you check it source code you'll see, that it uses remember inside, that's why it's marked with @Composable, and that's why you shouldn't bother about remembering some values manually.

Answered By - Philip Dukhov