Change View Model Scoping

app/src/main/java/com/cornellappdev/score/MainActivity.kt

@@ -1,17 +1,14 @@
 package com.cornellappdev.score
 
-import android.os.Build
 import android.os.Bundle
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
-import androidx.annotation.RequiresApi
 import androidx.appcompat.app.AppCompatActivity
 import com.cornellappdev.score.nav.root.RootNavigation
 import dagger.hilt.android.AndroidEntryPoint
 
 @AndroidEntryPoint
 class MainActivity : AppCompatActivity() {
-    @RequiresApi(Build.VERSION_CODES.O)
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         enableEdgeToEdge()

app/src/main/java/com/cornellappdev/score/nav/ScoreNavHost.kt

@@ -0,0 +1,46 @@
+package com.cornellappdev.score.nav
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
+import androidx.lifecycle.viewmodel.compose.LocalViewModelStoreOwner
+import androidx.navigation.NavHostController
+import androidx.navigation.compose.NavHost
+import androidx.navigation.compose.composable
+import com.cornellappdev.score.nav.root.ScoreScreens
+import com.cornellappdev.score.nav.root.ScoreScreens.Home
+import com.cornellappdev.score.screen.GameDetailsScreen
+import com.cornellappdev.score.screen.HomeScreen
+import com.cornellappdev.score.screen.PastGamesScreen
+
+@Composable
+fun ScoreNavHost(navController: NavHostController) {
+    // This ViewModelStoreOwner is used to scope the past and home screen view models to the root
+    //  screen instead of their individual tabs. This way the view models are not reconstructed
+    //  everytime you switch tabs.
+    val mainScreenViewModelStoreOwner = checkNotNull(LocalViewModelStoreOwner.current)
+
+    NavHost(
+        navController = navController,
+        startDestination = Home
+    ) {
+        composable<Home> {
+            CompositionLocalProvider(LocalViewModelStoreOwner provides mainScreenViewModelStoreOwner) {
+                HomeScreen(navigateToGameDetails = {
+                    navController.navigate(ScoreScreens.GameDetailsPage(""))
+                })
+            }
+        }
+        composable<ScoreScreens.ScoresScreen> {
+            CompositionLocalProvider(LocalViewModelStoreOwner provides mainScreenViewModelStoreOwner) {
+                PastGamesScreen(navigateToGameDetails = {
+                    navController.navigate(ScoreScreens.GameDetailsPage(""))
+                })
+            }
+        }
+        composable<ScoreScreens.GameDetailsPage> {
+            GameDetailsScreen(onBackArrow = {
+                navController.navigateUp()
+            })
+        }
+    }
+}

app/src/main/java/com/cornellappdev/score/nav/ScoreNavigationBar.kt

@@ -0,0 +1,61 @@
+package com.cornellappdev.score.nav
+
+import androidx.compose.material3.Icon
+import androidx.compose.material3.NavigationBar
+import androidx.compose.material3.NavigationBarItem
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.navigation.NavBackStackEntry
+import com.cornellappdev.score.nav.root.ScoreScreens
+import com.cornellappdev.score.nav.root.tabs
+import com.cornellappdev.score.nav.root.toScreen
+import com.cornellappdev.score.theme.CrimsonPrimary
+import com.cornellappdev.score.theme.GrayPrimary
+import com.cornellappdev.score.theme.Style.bodyMedium
+import com.cornellappdev.score.theme.White
+
+@Composable
+fun ScoreNavigationBar(
+    navigateToScreen: (ScoreScreens) -> Unit,
+    navBackStackEntry: NavBackStackEntry?,
+    modifier: Modifier = Modifier,
+) {
+    NavigationBar(modifier = modifier, containerColor = White) {
+        tabs.map { item ->
+            val isSelected = item.screen == navBackStackEntry?.toScreen()
+
+            NavigationBarItem(
+                selected = isSelected,
+                onClick = { navigateToScreen(item.screen) },
+                icon = {
+                    Icon(
+                        painter = painterResource(id = if (isSelected) item.selectedIcon else item.unselectedIcon),
+                        contentDescription = null,
+                        tint = Color.Unspecified
+                    )
+                },
+                label = {
+                    Text(
+                        text = item.label,
+                        style = bodyMedium,
+                        color = if (isSelected) {
+                            CrimsonPrimary
+                        } else {
+                            GrayPrimary
+                        }
+                    )
+                }
+            )
+        }
+    }
+}
+
+@Preview
+@Composable
+private fun ScoreNavigationBarPreview() {
+    ScoreNavigationBar({}, null)
+}

app/src/main/java/com/cornellappdev/score/nav/root/RootNavigation.kt

@@ -7,34 +7,23 @@ import androidx.compose.animation.core.rememberInfiniteTransition
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.padding
-import androidx.compose.material3.Icon
-import androidx.compose.material3.NavigationBar
-import androidx.compose.material3.NavigationBarItem
 import androidx.compose.material3.Scaffold
-import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.CompositionLocalProvider
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.res.painterResource
 import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.navigation.NavBackStackEntry
-import androidx.navigation.compose.NavHost
-import androidx.navigation.compose.composable
 import androidx.navigation.compose.currentBackStackEntryAsState
 import androidx.navigation.compose.rememberNavController
 import androidx.navigation.toRoute
 import com.cornellappdev.score.R
-import com.cornellappdev.score.nav.root.ScoreRootScreens.Home.toScreen
-import com.cornellappdev.score.screen.GameDetailsScreen
-import com.cornellappdev.score.screen.HomeScreen
-import com.cornellappdev.score.screen.PastGamesScreen
-import com.cornellappdev.score.theme.CrimsonPrimary
-import com.cornellappdev.score.theme.GrayPrimary
+import com.cornellappdev.score.nav.ScoreNavHost
+import com.cornellappdev.score.nav.ScoreNavigationBar
+import com.cornellappdev.score.nav.root.ScoreScreens.GameDetailsPage
+import com.cornellappdev.score.nav.root.ScoreScreens.Home
+import com.cornellappdev.score.nav.root.ScoreScreens.ScoresScreen
 import com.cornellappdev.score.theme.LocalInfiniteLoading
-import com.cornellappdev.score.theme.Style.bodyMedium
-import com.cornellappdev.score.theme.White
 import kotlinx.serialization.Serializable
 
 @Composable
@@ -67,93 +56,46 @@ fun RootNavigation(
         }
     }
 
+
     Scaffold(modifier = Modifier.fillMaxSize(), bottomBar = {
-        if (navBackStackEntry?.toScreen() is ScoreRootScreens.GameDetailsPage) {
+        if (navBackStackEntry?.toScreen() is GameDetailsPage) {
             return@Scaffold
         }
-        NavigationBar(containerColor = White) {
-            tabs.map { item ->
-                val isSelected = item.screen == navBackStackEntry?.toScreen()
-
-                NavigationBarItem(
-                    selected = isSelected,
-                    onClick = { navController.navigate(item.screen) },
-                    icon = {
-                        Icon(
-                            painter = painterResource(id = if (isSelected) item.selectedIcon else item.unselectedIcon),
-                            contentDescription = null,
-                            tint = Color.Unspecified
-                        )
-                    },
-                    label = {
-                        Text(
-                            text = item.label,
-                            style = bodyMedium,
-                            color = if (isSelected) {
-                                CrimsonPrimary
-                            } else {
-                                GrayPrimary
-                            }
-                        )
-                    }
-                )
-            }
-        }
+        ScoreNavigationBar({ navController.navigate(it) }, navBackStackEntry)
     }
     ) { innerPadding ->
         Box(modifier = Modifier.padding(innerPadding)) {
             CompositionLocalProvider(LocalInfiniteLoading provides animatedValue) {
-                NavHost(
-                    navController = navController,
-                    startDestination = ScoreRootScreens.Home
-                ) {
-                    composable<ScoreRootScreens.Home> {
-                        HomeScreen(navigateToGameDetails = {
-                            navController.navigate(ScoreRootScreens.GameDetailsPage(it))
-                        })
-                    }
-
-                    composable<ScoreRootScreens.GameDetailsPage> {
-                        GameDetailsScreen(onBackArrow = {
-                            navController.navigateUp()
-                        })
 
-                    }
-
-                    composable<ScoreRootScreens.ScoresScreen> {
-                        PastGamesScreen(navigateToGameDetails = {
-                            navController.navigate(ScoreRootScreens.GameDetailsPage(it))
-                        })
-                    }
-                }
+                ScoreNavHost(navController)
             }
         }
     }
 }
 
 
 @Serializable
-sealed class ScoreRootScreens {
+sealed class ScoreScreens {
     @Serializable
-    data object Home : ScoreRootScreens()
+    data object Home : ScoreScreens()
 
     @Serializable
-    data class GameDetailsPage(val gameId: String) : ScoreRootScreens()
+    data class GameDetailsPage(val gameId: String) : ScoreScreens()
 
     @Serializable
-    data object ScoresScreen : ScoreRootScreens()
-
-    fun NavBackStackEntry.toScreen(): ScoreRootScreens? =
-        when (destination.route?.substringAfterLast(".")?.substringBefore("/")) {
-            "Home" -> toRoute<Home>()
-            "GameDetailsPage" -> toRoute<GameDetailsPage>()
-            "ScoresScreen" -> toRoute<ScoresScreen>()
-            else -> throw IllegalArgumentException("Invalid screen")
-        }
+    data object ScoresScreen : ScoreScreens()
 }
 
+fun NavBackStackEntry.toScreen(): ScoreScreens? =
+    when (destination.route?.substringAfterLast(".")?.substringBefore("/")) {
+        "Home" -> toRoute<Home>()
+        "GameDetailsPage" -> toRoute<GameDetailsPage>()
+        "ScoresScreen" -> toRoute<ScoresScreen>()
+        else -> throw IllegalArgumentException("Invalid screen")
+    }
+
 data class NavItem(
-    val screen: ScoreRootScreens,
+    val screen: ScoreScreens,
     val label: String,
     val unselectedIcon: Int,
     val selectedIcon: Int
@@ -164,12 +106,12 @@ val tabs = listOf(
         label = "Schedule",
         unselectedIcon = R.drawable.ic_schedule,
         selectedIcon = R.drawable.ic_schedule_filled,
-        screen = ScoreRootScreens.Home,
+        screen = ScoreScreens.Home,
     ),
     NavItem(
         label = "Scores",
         unselectedIcon = R.drawable.ic_scores,
         selectedIcon = R.drawable.ic_scores_filled,
-        screen = ScoreRootScreens.ScoresScreen,
+        screen = ScoreScreens.ScoresScreen,
     ),
 )

app/src/main/java/com/cornellappdev/score/nav/root/RootNavigationRepository.kt

@@ -5,4 +5,4 @@ import javax.inject.Inject
 import javax.inject.Singleton
 
 @Singleton
-class RootNavigationRepository @Inject constructor() : BaseNavigationRepository<ScoreRootScreens>()
+class RootNavigationRepository @Inject constructor() : BaseNavigationRepository<ScoreScreens>()

app/src/main/java/com/cornellappdev/score/nav/root/RootNavigationViewModel.kt

@@ -1,7 +1,7 @@
 package com.cornellappdev.score.nav.root
 
-import com.cornellappdev.score.viewmodel.BaseViewModel
 import com.cornellappdev.score.util.UIEvent
+import com.cornellappdev.score.viewmodel.BaseViewModel
 import dagger.hilt.android.lifecycle.HiltViewModel
 import javax.inject.Inject
 
@@ -13,7 +13,7 @@ class RootNavigationViewModel @Inject constructor(
 ) {
 
     data class RootNavigationUiState(
-        val navigationEvent: UIEvent<ScoreRootScreens>? = null,
+        val navigationEvent: UIEvent<ScoreScreens>? = null,
     )
 
     init {