Extract logic for wrapping a NavBackStackEntry's Composable content [187229439]

Fixed

Feature Request

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Description

il...@google.com

created issue #1

May 5, 2021 01:02AM

Component used: Navigation Compose

Navigation Compose's NavHost (and any other Compose related Navigator), must all use the same pattern of:

val saveableStateHolder = rememberSaveableStateHolder()
CompositionLocalProvider(
    LocalViewModelStoreOwner provides backStackEntry,
    LocalLifecycleOwner provides backStackEntry,
    LocalSavedStateRegistryOwner provides backStackEntry
) {
    saveableStateHolder.SaveableStateProvider {
        destination.content(backStackEntry)
    }
}

It would be nice if we could extract that out into a reusable container, so that any Navigator could write:

val saveableStateHolder = rememberSaveableStateHolder()
backStackEntry.compositionLocalProvider {
    destination.content(backStackEntry)
}

Where a fun NavBackStackEntry.compositionLocalProvider(content: @Composable () -> Unit) would encapsulate all of the details for you.

I'm not particularly tied to the name / use of an extension, but I like the reuse of CompositionLocalProvider in a way that doesn't add an overload in a different package to the global namespace.

Comments

il...@google.com <il...@google.com> #2May 5, 2021 05:21PM

I realize that this code would need to change slightly to take the SaveableStateHolder as input, but the idea remains the same.

ap...@google.com <ap...@google.com> #3May 7, 2021 05:05AM

Marked as fixed.

Project: platform/frameworks/support
Branch: androidx-main

commit a8c1f68f0bdbfce87cda1331a07af6ac0fb1594e
Author: Jossi Wolf <10628007+jossiwolf@users.noreply.github.com>
Date: Thu May 06 23:13:31 2021

[GH] [Navigation] Introduce NavBackStackEntry#provideToCompositionLocals

…that provides the NavBackStackEntry to the composition locals needed for all Compose-related navigators.

Relnote: Introduced a new NavBackStackEntry#provideToCompositionLocals that provides the NavBackStackEntry to the relevant composition locals.

## Testing

Test: NavBackStackEntryProviderTest

`NavBackStackEntryProviderTest#testSaveableValueInContentIsSaved` is pretty much just copied from [RememberSaveableTest](

https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:compose/runtime/runtime-saveable/src/androidAndroidTest/kotlin/androidx/compose/runtime/saveable/RememberSaveableTest.kt) and as always, I'll be very happy about suggestions on improving the tests and additional tests!

## Issues Fixed

Fixes:

b/187229439

This is an imported pull request from

https://github.com/androidx/androidx/pull/175.

Resolves #175
Github-Pr-Head-Sha: a8100a09daa0e688fd278e43f1dd27dd22d718ac
GitOrigin-RevId: 7441a30ed46421dfd25c29fec168f766d674f88e
Change-Id: I25a46dfefc52adc1411536359a285bfbc4fb2e38

M navigation/navigation-compose/api/current.txt
M navigation/navigation-compose/api/public_plus_experimental_current.txt
M navigation/navigation-compose/api/restricted_current.txt
A navigation/navigation-compose/src/androidTest/java/androidx/navigation/compose/NavBackStackEntryProviderTest.kt
A navigation/navigation-compose/src/main/java/androidx/navigation/compose/NavBackStackEntryProvider.kt
M navigation/navigation-compose/src/main/java/androidx/navigation/compose/NavHost.kt

https://android-review.googlesource.com/1698805

Issue 187229439

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il...@google.com <il...@google.com> #2May 5, 2021 05:21PM

ap...@google.com <ap...@google.com> #3May 7, 2021 05:05AM

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