Fragment Container in Jetpack Compose

Question

I want to develop a single Activity multi fragments Apps using Jetpack Compose. For recyclerView, we have Vertical and HorizontalScroller. But, for fragments what should I use.

fun loadFragment(fragment: Fragment) {
            val transaction:FragmentTransaction = supportFragmentManager.beginTransaction()
            transaction.replace(R.id.f_container, fragment)
            transaction.addToBackStack(null)
            transaction.commit()
        }

In this case, I don't have R.id.f_container because I'm creating UI using only compose.

<FrameLayout
    android:id="@+id/f_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"`enter code here`
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    app:layout_constraintEnd_toEndOf="parent"
    tools:layout_editor_absoluteY="-56dp">
</FrameLayout>

Answer 1

You can create your own @Composable FragmentContainer function

@Composable
fun FragmentContainer(
    modifier: Modifier = Modifier,
    fragmentManager: FragmentManager,
    commit: FragmentTransaction.(containerId: Int) -> Unit
) {
    val containerId by rememberSaveable { mutableStateOf(View.generateViewId()) }
    var initialized by rememberSaveable { mutableStateOf(false) }
    AndroidView(
        modifier = modifier,
        factory = { context ->
            FragmentContainerView(context)
                .apply { id = containerId }
        },
        update = { view ->
            if (!initialized) {
                fragmentManager.commit { commit(view.id) }
                initialized = true
            } else {
                fragmentManager.onContainerAvailable(view)
            }
        }
    )
}

/** Access to package-private method in FragmentManager through reflection */
private fun FragmentManager.onContainerAvailable(view: FragmentContainerView) {
    val method = FragmentManager::class.java.getDeclaredMethod(
        "onContainerAvailable",
        FragmentContainerView::class.java
    )
    method.isAccessible = true
    method.invoke(this, view)
}

and then use it in activity

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContent {
        FragmentContainer(
            modifier = Modifier.fillMaxSize(),
            fragmentManager = supportFragmentManager,
            commit = { add(it, YourFragment()) }
        )
    }
}

or in fragment

override fun onCreateView(
    inflater: LayoutInflater,
    container: ViewGroup?,
    savedInstanceState: Bundle?
): View = ComposeView(requireContext()).apply {
    setContent {
        FragmentContainer(
            modifier = Modifier.fillMaxSize(),
            fragmentManager = parentFragmentManager,
            commit = { add(it, YourNestedFragment()) }
        )
    }
}