I would like to use unconsumed WindowInsets as contentPadding in LazyColumn. Currently i use following code:

LazyColumn(
    contentPadding = WindowInsets.systemBars.asPaddingValues(),
) {

But this does not consider already consumed insets. Is there a method to get unconsumed insets? I looked into the inset modifier api and they use internal variables to keep track of consumed insets.

I had more or less the exact same need as you, and the only way to “extract” the consumed window insets from inside the composition local that they use to communicate it, is through the use of

onConsumedWindowInsetsChanged

modifier. Here’s what I do https://github.com/HedvigInsurance/android/blob/e72564f334bcd3a61d1f62a9eeccc5d63d[…]tlin/com/hedvig/android/feature/home/home/ui/HomeDestination.kt

Thank you very much for pointing this out. Unfortunately very complicated solution for such a common use case. But thank you Stylianos.

And for the horizontal padding i put it into the normal modifier and not using content padding at all

What do you mean by “normal” modifier here?

LazyColumn(
    modifier = Modifier
        .windowInsetsPadding(WindowInsets.systemBars.only(WindowInsetsSides.Horizontal)
        )
) {
    item {
        Spacer(Modifier
            .windowInsetsPadding(WindowInsets.systemBars.only(<http://WindowInsetsSides.Top|WindowInsetsSides.Top>))
        )
    }
    items ...
    item {
        Spacer(Modifier
            .windowInsetsPadding(WindowInsets.systemBars.only(WindowInsetsSides.Bottom))
        )
    }
}

This is my solution but also a little bit too complicated for my taste 😞

No this works too. But with a caveat! If your items ever need to go outside of those horizontal bounds, they will appear cut-off. Funny enough that I was showing this off just the other day to some colleagues of mine Basically you get the cut-off as these two images show

I came up with following code to make it a little bit easier to use on many places:

class PaddingValueProvider(
    val modifier: Modifier
) {
    var paddingValues: PaddingValues by mutableStateOf(PaddingValues())
        internal set
}

@Composable
fun insetsPaddingValuesProvider(insets: WindowInsets): PaddingValueProvider {
    val density = LocalDensity.current
    var consumedWindowInsets by remember { mutableStateOf(WindowInsets(0.dp)) }
    val provider = remember {
        PaddingValueProvider(
            modifier = Modifier.onConsumedWindowInsetsChanged {
                log("consumedInsets: $it")
                consumedWindowInsets = it
            }
        )
    }

    LaunchedEffect(Unit) {
        snapshotFlow { consumedWindowInsets }.collect {
            provider.paddingValues = insets.exclude(consumedWindowInsets).asPaddingValues(density)
            log("Padding values: ${provider.paddingValues}")
        }
    }

    return provider
}

Usage looks than like this:

val paddingValueProvider = insetsPaddingValuesProvider(insets = WindowInsets.systemBars)

LazyColumn(
    modifier = paddingValueProvider.modifier,
    contentPadding = paddingValueProvider.paddingValues
) {
    items ...
}

Hmm not sure about this modifier which applies to nothing and is just stored as a variable, does that even work?

Ok it looks like this code will also work and is much easier:

@Composable
fun insetsPaddingValues(insets: WindowInsets): PaddingValues {
    val density = LocalDensity.current
    var paddingValues by remember { mutableStateOf(PaddingValues()) }
    Spacer(modifier = Modifier.onConsumedWindowInsetsChanged(
        block = {
            paddingValues = insets.exclude(it).asPaddingValues(density)
        }
    ))
    return paddingValues
}

Usage is than very easy:

LazyColumn(
    contentPadding = insetsPaddingValues(insets = WindowInsets.systemBars)
) {
    items ...
}

So you got a composable function, which returns an instance of

PaddingValues

but also at the same time emits some UI by using the

Spacer

. I think that’s a big no-no, as mentioned here https://android.googlesource.com/platform/frameworks/support/+/androidx-main/compose/docs/compose-api-guidelines.md#emit-xor-return-a-value

Yes you are right. But it is a spacer which will take 0,0 size 😄 I think i will use it until the Android devs add some usable API

If you’re feeling like it, it would be nice to make a feature request about this, and provide what you did to solve your issue by having to break the compose api guidelines to make it happen. This new API that you mention won’t ever happen if we don’t ask for it 😊

I will file a feature request later and post the thread here.

Thank you!