Forked from joost-klitsie/RememberViewModelStoreOwner.kt
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August 30, 2024 03:04
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rememberViewModelStoreOwner example implementation
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| import androidx.compose.runtime.* | |
| import androidx.compose.ui.platform.LocalLifecycleOwner | |
| import androidx.lifecycle.* | |
| import androidx.lifecycle.viewmodel.compose.LocalViewModelStoreOwner | |
| import androidx.lifecycle.viewmodel.compose.viewModel | |
| import kotlinx.coroutines.* | |
| import kotlinx.coroutines.flow.* | |
| @Composable | |
| fun rememberViewModelStoreOwner( | |
| key: Any?, | |
| ): ViewModelStoreOwner { | |
| val viewModelKey = "rememberViewModelStoreOwner#" + currentCompositeKeyHash.toString(36) | |
| val localLifecycle = LocalLifecycleOwner.current.lifecycle | |
| val viewModelStoreOwnerViewModel = viewModel<ViewModelStoreOwnerViewModel> { | |
| ViewModelStoreOwnerViewModel() | |
| } | |
| val viewModelStore = viewModelStoreOwnerViewModel.get(viewModelKey, key, localLifecycle) | |
| remember { | |
| object : RememberObserver { | |
| override fun onAbandoned() { | |
| viewModelStoreOwnerViewModel.detachComposable(viewModelKey) | |
| } | |
| override fun onForgotten() { | |
| viewModelStoreOwnerViewModel.detachComposable(viewModelKey) | |
| } | |
| override fun onRemembered() { | |
| viewModelStoreOwnerViewModel.attachComposable(viewModelKey) | |
| } | |
| } | |
| } | |
| return viewModelStore | |
| } | |
| @Composable | |
| fun WithViewModelStoreOwner( | |
| key: Any?, | |
| content: @Composable () -> Unit, | |
| ) { | |
| CompositionLocalProvider( | |
| value = LocalViewModelStoreOwner provides rememberViewModelStoreOwner(key), | |
| content = content, | |
| ) | |
| } | |
| @Stable | |
| private class ViewModelStoreOwnerViewModel : ViewModel() { | |
| private var attachedComposables = mapOf<String, AttachedComposable>() | |
| fun get(hashKey: String, key: Any?, lifecycle: Lifecycle) = attachedComposables[hashKey]?.let { | |
| it.update(key, lifecycle) | |
| it.viewModelStore | |
| } ?: run { | |
| val attachedComposable = AttachedComposable(hashKey, key, lifecycle) | |
| attachedComposables += hashKey to attachedComposable | |
| attachedComposable.viewModelStore | |
| } | |
| fun attachComposable(hashKey: String) { | |
| attachedComposables[hashKey]?.attachComposable() | |
| } | |
| fun detachComposable(hashKey: String) { | |
| attachedComposables[hashKey]?.detachComposable() | |
| } | |
| override fun onCleared() { | |
| attachedComposables.keys.forEach { | |
| dispose(it) | |
| } | |
| super.onCleared() | |
| } | |
| private fun dispose(hashKey: String) { | |
| attachedComposables[hashKey]?.let { | |
| it.clear() | |
| attachedComposables -= hashKey | |
| } | |
| } | |
| private inner class AttachedComposable( | |
| private val hashKey: String, | |
| private var key: Any?, | |
| initialLifecycle: Lifecycle, | |
| ) { | |
| val viewModelStore: ViewModelStoreOwner = object : ViewModelStoreOwner { | |
| override val viewModelStore = ViewModelStore() | |
| } | |
| private val supervisorJob: CompletableJob = SupervisorJob() | |
| private val scope: CoroutineScope = viewModelScope + supervisorJob | |
| private val attachedLifecycle = MutableStateFlow<Lifecycle?>(initialLifecycle) | |
| private val isAttachedToComposable = MutableSharedFlow<Boolean>() | |
| init { | |
| scope.launch { | |
| attachedLifecycle | |
| .flatMapLatest { lifecycle -> lifecycle?.eventFlow ?: emptyFlow() } | |
| .collectLatest { | |
| if (it == Lifecycle.Event.ON_DESTROY) { | |
| attachedLifecycle.update { null } | |
| } | |
| } | |
| } | |
| scope.launch { | |
| isAttachedToComposable.collectLatest { isAttached -> | |
| when { | |
| // If we are attached or we are destroyed, we do not need to do anything | |
| isAttached || attachedLifecycle.value == null -> return@collectLatest | |
| // If we are detached and the lifecycle state is resumed, we should reset the view model store | |
| attachedLifecycle.value?.currentState == Lifecycle.State.RESUMED -> { | |
| dispose(hashKey) | |
| } | |
| else -> { | |
| // We wait for the lifecycle event ON_RESUME to be triggered before resetting the ViewModelStore | |
| // If in the mean time we are attached again, this work is cancelled | |
| attachedLifecycle | |
| .flatMapLatest { lifecycle -> lifecycle?.eventFlow ?: emptyFlow() } | |
| // Wait for first event that matches ON_RESUME. | |
| .firstOrNull { it == Lifecycle.Event.ON_RESUME } ?: return@collectLatest | |
| dispose(hashKey) | |
| } | |
| } | |
| } | |
| } | |
| } | |
| fun clear() { | |
| supervisorJob.cancelChildren() | |
| viewModelStore.viewModelStore.clear() | |
| } | |
| fun update(key: Any?, lifecycle: Lifecycle) { | |
| if (key != this.key) { | |
| this.key = key | |
| viewModelStore.viewModelStore.clear() | |
| } | |
| attachedLifecycle.update { lifecycle } | |
| } | |
| fun attachComposable() { | |
| scope.launch { isAttachedToComposable.emit(true) } | |
| } | |
| fun detachComposable() { | |
| scope.launch { isAttachedToComposable.emit(false) } | |
| } | |
| } | |
| } |
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