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// package com.example.project |
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import androidx.compose.runtime.Composable |
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import androidx.compose.runtime.MutableState |
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import androidx.compose.runtime.getValue |
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import androidx.compose.runtime.mutableStateOf |
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import androidx.compose.runtime.remember |
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import androidx.compose.runtime.saveable.rememberSerializable |
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import androidx.compose.runtime.setValue |
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import androidx.compose.runtime.snapshots.SnapshotStateList |
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import androidx.compose.runtime.toMutableStateList |
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import androidx.navigation3.runtime.NavBackStack |
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import androidx.navigation3.runtime.NavEntry |
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import androidx.navigation3.runtime.NavKey |
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import androidx.navigation3.runtime.rememberDecoratedNavEntries |
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import androidx.navigation3.runtime.rememberNavBackStack |
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import androidx.navigation3.runtime.rememberSaveableStateHolderNavEntryDecorator |
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import androidx.navigation3.runtime.serialization.NavKeySerializer |
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import androidx.savedstate.compose.serialization.serializers.MutableStateSerializer |
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/** |
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* Create a navigation state that persists config changes and process death. |
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*/ |
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@Composable |
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fun rememberNavigationState( |
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startRoute: NavKey, |
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topLevelRoutes: Set<NavKey> |
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): NavigationState { |
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val topLevelRoute = rememberSerializable( |
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startRoute, topLevelRoutes, |
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serializer = MutableStateSerializer(NavKeySerializer()) |
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) { |
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mutableStateOf(startRoute) |
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} |
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val backStacks = topLevelRoutes.associateWith { key -> rememberNavBackStack(key) } |
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return remember(startRoute, topLevelRoutes) { |
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NavigationState( |
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startRoute = startRoute, |
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topLevelRoute = topLevelRoute, |
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backStacks = backStacks |
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) |
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} |
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} |
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/** |
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* State holder for navigation state. |
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* |
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* @param startRoute - the start route. The user will exit the app through this route. |
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* @param topLevelRoute - the current top level route |
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* @param backStacks - the back stacks for each top level route |
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*/ |
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class NavigationState( |
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val startRoute: NavKey, |
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topLevelRoute: MutableState<NavKey>, |
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val backStacks: Map<NavKey, NavBackStack<NavKey>> |
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) { |
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var topLevelRoute: NavKey by topLevelRoute |
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val stacksInUse: List<NavKey> |
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get() = if (topLevelRoute == startRoute) { |
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listOf(startRoute) |
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} else { |
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listOf(startRoute, topLevelRoute) |
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} |
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} |
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/** |
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* Convert NavigationState into NavEntries. |
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*/ |
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@Composable |
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fun NavigationState.toEntries( |
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entryProvider: (NavKey) -> NavEntry<NavKey> |
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): SnapshotStateList<NavEntry<NavKey>> { |
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val decoratedEntries = backStacks.mapValues { (_, stack) -> |
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val decorators = listOf( |
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rememberSaveableStateHolderNavEntryDecorator<NavKey>(), |
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) |
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rememberDecoratedNavEntries( |
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backStack = stack, |
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entryDecorators = decorators, |
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entryProvider = entryProvider |
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) |
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} |
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return stacksInUse |
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.flatMap { decoratedEntries[it] ?: emptyList() } |
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.toMutableStateList() |
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} |
