Improve top bar

Change-Id: I7b3ef8fb15990773b6aee9c6c2efc10fccb7be19

app/src/main/java/com/google/samples/apps/nowinandroid/ui/NiaApp.kt

@@ -145,7 +145,7 @@ fun NiaApp(
                             destinations = appState.topLevelDestinations,
                             destinationsWithUnreadResources = unreadDestinations,
                             onNavigateToDestination = appState::navigateToTopLevelDestination,
-                            currentDestination = appState.currentBackStackEntry?.destination,
+                            currentDestination = appState.currentDestination,
                             modifier = Modifier.testTag("NiaBottomBar"),
                         )
                     }
@@ -167,7 +167,7 @@ fun NiaApp(
                             destinations = appState.topLevelDestinations,
                             destinationsWithUnreadResources = unreadDestinations,
                             onNavigateToDestination = appState::navigateToTopLevelDestination,
-                            currentDestination = appState.currentBackStackEntry?.destination,
+                            currentDestination = appState.currentDestination,
                             modifier = Modifier
                                 .testTag("NiaNavRail")
                                 .safeDrawingPadding(),
@@ -176,10 +176,10 @@ fun NiaApp(
 
                     Column(Modifier.fillMaxSize()) {
                         // Show the top app bar on top level destinations.
-                        val destination = appState.currentTopLevelDestination
+                        val destination = appState.topBarTitle
                         if (destination != null) {
                             NiaTopAppBar(
-                                titleRes = destination.titleTextId,
+                                titleRes = destination,
                                 navigationIcon = NiaIcons.Search,
                                 navigationIconContentDescription = stringResource(
                                     id = settingsR.string.top_app_bar_navigation_icon_description,

app/src/main/java/com/google/samples/apps/nowinandroid/ui/NiaAppState.kt

@@ -21,10 +21,12 @@ import androidx.compose.material3.windowsizeclass.WindowSizeClass
 import androidx.compose.material3.windowsizeclass.WindowWidthSizeClass
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.Stable
+import androidx.compose.runtime.getValue
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
 import androidx.navigation.NavBackStackEntry
 import androidx.navigation.NavController
+import androidx.navigation.NavDestination
 import androidx.navigation.NavGraph.Companion.findStartDestination
 import androidx.navigation.NavHostController
 import androidx.navigation.compose.currentBackStackEntryAsState
@@ -86,24 +88,34 @@ class NiaAppState(
     networkMonitor: NetworkMonitor,
     userNewsResourceRepository: UserNewsResourceRepository,
 ) {
-    val currentBackStackEntry: NavBackStackEntry?
+    val currentDestination: NavDestination?
         @Composable get() = navController
-            .currentBackStackEntryAsState().value
+            .currentBackStackEntryAsState().value?.destination
 
-    val currentTopLevelDestination: TopLevelDestination?
+    val topBarTitle: Int?
         @Composable get() {
-            val route: String? = currentBackStackEntry?.destination?.route
-            val arguments: Bundle? = currentBackStackEntry?.arguments
+            val backStackEntry: NavBackStackEntry? by navController.currentBackStackEntryAsState()
+            val route: String? = backStackEntry?.destination?.route
+            val arguments: Bundle? = backStackEntry?.arguments
             return when {
-                route == forYouNavigationRoute -> FOR_YOU
-                route == bookmarksRoute -> BOOKMARKS
+                route == forYouNavigationRoute -> FOR_YOU.titleTextId
+                route == bookmarksRoute -> BOOKMARKS.titleTextId
                 route == interestsRoute &&
-                    (arguments?.getString(topicIdArg) == null || shouldShowTwoPane) -> INTERESTS
+                    (arguments?.getString(topicIdArg) == null || shouldShowTwoPane) -> INTERESTS.titleTextId
                 else -> null
             }
         }
+
+    val currentTopLevelDestination: TopLevelDestination?
+        @Composable get() = when (currentDestination?.route) {
+            forYouNavigationRoute -> FOR_YOU
+            bookmarksRoute -> BOOKMARKS
+            interestsRoute -> INTERESTS
+            else -> null
+        }
+
     val shouldShowGradientBackground: Boolean
-        @Composable get() = currentBackStackEntry?.destination?.route == forYouNavigationRoute
+        @Composable get() = currentTopLevelDestination == FOR_YOU
 
     val shouldShowBottomBar: Boolean
         get() = windowSizeClass.widthSizeClass == WindowWidthSizeClass.Compact

feature/interests/src/main/java/com/google/samples/apps/nowinandroid/feature/interests/TopicScreen.kt

@@ -30,6 +30,7 @@ import androidx.compose.foundation.layout.windowInsetsBottomHeight
 import androidx.compose.foundation.lazy.grid.GridCells
 import androidx.compose.foundation.lazy.grid.GridItemSpan
 import androidx.compose.foundation.lazy.grid.LazyGridScope
+import androidx.compose.foundation.lazy.grid.LazyGridState
 import androidx.compose.foundation.lazy.grid.LazyVerticalGrid
 import androidx.compose.foundation.lazy.grid.rememberLazyGridState
 import androidx.compose.foundation.selection.selectableGroup
@@ -59,9 +60,6 @@ import com.google.samples.apps.nowinandroid.core.ui.TrackScrollJank
 import com.google.samples.apps.nowinandroid.core.ui.UserNewsResourcePreviewParameterProvider
 import com.google.samples.apps.nowinandroid.core.ui.newsFeed
 import com.google.samples.apps.nowinandroid.feature.interests.R.string
-import com.google.samples.apps.nowinandroid.feature.interests.TopicUiState.Error
-import com.google.samples.apps.nowinandroid.feature.interests.TopicUiState.Loading
-import com.google.samples.apps.nowinandroid.feature.interests.TopicUiState.Success
 
 @Composable
 internal fun TopicScreen(
@@ -72,13 +70,13 @@ internal fun TopicScreen(
     onBookmarkChanged: (String, Boolean) -> Unit,
     onNewsResourceViewed: (String) -> Unit,
     modifier: Modifier = Modifier,
+    gridState: LazyGridState = rememberLazyGridState(),
 ) {
-    val state = rememberLazyGridState()
-    TrackScrollJank(scrollableState = state, stateName = "topic:screen")
+    TrackScrollJank(scrollableState = gridState, stateName = "topic:screen")
 
     LazyVerticalGrid(
         columns = GridCells.Adaptive(300.dp),
-        state = state,
+        state = gridState,
         verticalArrangement = Arrangement.spacedBy(16.dp),
         modifier = modifier
             .selectableGroup()
@@ -93,13 +91,13 @@ internal fun TopicScreen(
                 )
             }
 
-            Error -> {
+            TopicUiState.Error -> {
                 item {
                     Text(text = stringResource(id = string.topic_error))
                 }
             }
 
-            is Success -> {
+            is TopicUiState.Success -> {
                 item(span = { GridItemSpan(maxLineSpan) }) {
                     TopicToolbar(
                         onBackClick = onBackClick,
@@ -238,7 +236,7 @@ fun TopicScreenPopulated(
     NiaTheme {
         NiaBackground {
             TopicScreen(
-                topicUiState = Success(
+                topicUiState = TopicUiState.Success(
                     followableTopic = userNewsResources[0].followableTopics[0],
                     newsResources = userNewsResources,
                 ),
@@ -258,7 +256,7 @@ fun TopicScreenLoading() {
     NiaTheme {
         NiaBackground {
             TopicScreen(
-                topicUiState = Loading,
+                topicUiState = TopicUiState.Loading,
                 onBackClick = {},
                 onFollowClick = { _, _ -> },
                 onBookmarkChanged = { _, _ -> },