feat(android): link up bottombar visibility with scroll

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Change submitter text to 'authored' when applicable
 - Unread comments now have a brighter background rather than a text badge
 - Opening posts you have previously seen will show the number of new comments since last visit
+- Bottom navigation's visibility now interacts with the scroll behavior of the post lists
 
 ## [1.48.0] - 2024-06-05
 

android/src/main/kotlin/dev/msfjarvis/claw/android/ui/decorations/ClawNavigationBar.kt

@@ -13,8 +13,10 @@ import androidx.compose.animation.core.LinearOutSlowInEasing
 import androidx.compose.animation.core.tween
 import androidx.compose.animation.slideInVertically
 import androidx.compose.animation.slideOutVertically
+import androidx.compose.material3.BottomAppBar
+import androidx.compose.material3.BottomAppBarScrollBehavior
+import androidx.compose.material3.ExperimentalMaterial3Api
 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
@@ -29,11 +31,13 @@ import kotlinx.collections.immutable.ImmutableList
 
 const val AnimationDuration = 100
 
+@OptIn(ExperimentalMaterial3Api::class)
 @Composable
 fun ClawNavigationBar(
   navController: NavController,
   items: ImmutableList<NavigationItem>,
   isVisible: Boolean,
+  scrollBehavior: BottomAppBarScrollBehavior,
   modifier: Modifier = Modifier,
 ) {
   AnimatedVisibility(
@@ -52,7 +56,7 @@ fun ClawNavigationBar(
       ),
     modifier = Modifier,
   ) {
-    NavigationBar(modifier = modifier) {
+    BottomAppBar(modifier = modifier, scrollBehavior = scrollBehavior) {
       val navBackStackEntry = navController.currentBackStackEntryAsState().value
       val currentDestination = navBackStackEntry?.destination
       items.forEach { navItem ->

android/src/main/kotlin/dev/msfjarvis/claw/android/ui/screens/LobstersPostsScreen.kt

@@ -26,6 +26,7 @@ import androidx.compose.material.icons.filled.Whatshot
 import androidx.compose.material.icons.outlined.FavoriteBorder
 import androidx.compose.material.icons.outlined.NewReleases
 import androidx.compose.material.icons.outlined.Whatshot
+import androidx.compose.material3.BottomAppBarDefaults
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
@@ -44,6 +45,7 @@ import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.ui.ExperimentalComposeUiApi
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.shadow
+import androidx.compose.ui.input.nestedscroll.nestedScroll
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.res.stringResource
@@ -110,6 +112,8 @@ fun LobstersPostsScreen(
   val snackbarHostState = remember { SnackbarHostState() }
   val postActions = rememberPostActions(context, urlLauncher, navController, viewModel)
 
+  val scrollBehavior = BottomAppBarDefaults.exitAlwaysScrollBehavior()
+
   val hottestPosts = viewModel.hottestPosts.collectAsLazyPagingItems()
   val newestPosts = viewModel.newestPosts.collectAsLazyPagingItems()
   val savedPosts by viewModel.savedPostsByMonth.collectAsState(persistentMapOf())
@@ -205,11 +209,15 @@ fun LobstersPostsScreen(
           navController = navController,
           items = navItems,
           isVisible = currentDestination.any(navDestinations),
+          scrollBehavior = scrollBehavior,
         )
       }
     },
     snackbarHost = { SnackbarHost(snackbarHostState) },
-    modifier = modifier.semantics { testTagsAsResourceId = true },
+    modifier =
+      modifier.nestedScroll(scrollBehavior.nestedScrollConnection).semantics {
+        testTagsAsResourceId = true
+      },
   ) { paddingValues ->
     Row(modifier = Modifier.padding(paddingValues)) {
       AnimatedVisibility(visible = navigationType == ClawNavigationType.NAVIGATION_RAIL) {