fix: reset scroll state only between tab switching, not within the same tab

Author: RyanCheung555

app/src/main/java/com/cornellappdev/transit/ui/components/home/EcosystemBottomSheetContent.kt

@@ -10,9 +10,11 @@ import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.LazyListState
 import androidx.compose.foundation.lazy.LazyListScope
 import androidx.compose.foundation.lazy.LazyRow
 import androidx.compose.foundation.lazy.items
+import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.HorizontalDivider
 import androidx.compose.material3.ModalBottomSheet
@@ -83,6 +85,7 @@ fun EcosystemBottomSheetContent(
     onRemoveAppliedFilter: (FavoritesFilterSheetState) -> Unit,
     operatingHoursToString: (List<DayOperatingHours>) -> AnnotatedString,
     distanceStringToPlace: (Double?, Double?) -> String,
+    listState: LazyListState,
 ) {
     Column(modifier = modifier) {
         Row(
@@ -129,7 +132,8 @@ fun EcosystemBottomSheetContent(
             appliedFilters = appliedFilters,
             onRemoveAppliedFilter = onRemoveAppliedFilter,
             operatingHoursToString = operatingHoursToString,
-            distanceStringToPlace = distanceStringToPlace
+            distanceStringToPlace = distanceStringToPlace,
+            listState = listState
         )
     }
 
@@ -164,6 +168,7 @@ private fun BottomSheetFilteredContent(
     onRemoveAppliedFilter: (FavoritesFilterSheetState) -> Unit,
     operatingHoursToString: (List<DayOperatingHours>) -> AnnotatedString,
     distanceStringToPlace: (Double?, Double?) -> String,
+    listState: LazyListState,
 ) {
     Column {
         if (currentFilter == FilterState.FAVORITES) {
@@ -185,6 +190,7 @@ private fun BottomSheetFilteredContent(
         val isFilterBarHidden = currentFilter == FilterState.FAVORITES && appliedFilters.isEmpty()
         key(currentFilter, appliedFilters) {
             LazyColumn(
+                state = listState,
                 contentPadding = PaddingValues(
                     start = 12.dp,
                     end = 12.dp,
@@ -658,7 +664,8 @@ private fun PreviewEcosystemBottomSheet() {
         onFilterToggle = {},
         onRemoveAppliedFilter = {},
         operatingHoursToString = { _ -> AnnotatedString("") },
-        distanceStringToPlace = { _, _ -> "" }
+        distanceStringToPlace = { _, _ -> "" },
+        listState = rememberLazyListState()
     )
 }
 
@@ -826,7 +833,8 @@ private fun PreviewBottomSheetFilteredContentFavorites() {
         ),
         onRemoveAppliedFilter = {},
         operatingHoursToString = { _ -> AnnotatedString("Open • 10am - 4pm") },
-        distanceStringToPlace = { _, _ -> "distance" }
+        distanceStringToPlace = { _, _ -> "distance" },
+        listState = rememberLazyListState()
     )
 }
 

app/src/main/java/com/cornellappdev/transit/ui/screens/HomeScreen.kt

@@ -17,6 +17,8 @@ import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.wrapContentHeight
 import androidx.compose.foundation.layout.wrapContentWidth
+import androidx.compose.foundation.lazy.LazyListState
+import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.outlined.Info
@@ -71,6 +73,7 @@ import com.cornellappdev.transit.ui.theme.IconGray
 import com.cornellappdev.transit.ui.theme.MetadataGray
 import com.cornellappdev.transit.ui.viewmodels.EcosystemSheetState
 import com.cornellappdev.transit.ui.viewmodels.FavoritesViewModel
+import com.cornellappdev.transit.ui.viewmodels.FilterState
 import com.cornellappdev.transit.ui.viewmodels.HomeViewModel
 import com.cornellappdev.transit.ui.viewmodels.SearchBarUIState
 import com.cornellappdev.transit.util.BOTTOM_SHEET_MAX_HEIGHT_PERCENT
@@ -290,6 +293,20 @@ fun HomeScreen(
 
     // Favorites BottomSheet (Filters BottomSheet for ecosystem)
     if (ECOSYSTEM_FLAG) {
+        val favoritesListState = rememberLazyListState()
+        val gymsListState = rememberLazyListState()
+        val eateriesListState = rememberLazyListState()
+        val librariesListState = rememberLazyListState()
+        val printersListState = rememberLazyListState()
+
+        fun listStateFor(filter: FilterState): LazyListState = when (filter) {
+            FilterState.FAVORITES -> favoritesListState
+            FilterState.GYMS -> gymsListState
+            FilterState.EATERIES -> eateriesListState
+            FilterState.LIBRARIES -> librariesListState
+            FilterState.PRINTERS -> printersListState
+        }
+
         var ecosystemSheetState by remember {
             mutableStateOf<EcosystemSheetState>(
                 EcosystemSheetState.Tabs
@@ -333,7 +350,16 @@ fun HomeScreen(
                         EcosystemBottomSheetContent(
                             filters = homeViewModel.filterList,
                             activeFilter = filterStateValue,
-                            onFilterClick = homeViewModel::setCategoryFilter,
+                            onFilterClick = { selectedFilter ->
+                                if (selectedFilter == filterStateValue) {
+                                    return@EcosystemBottomSheetContent
+                                }
+
+                                homeViewModel.setCategoryFilter(selectedFilter)
+                                scope.launch {
+                                    listStateFor(selectedFilter).scrollToItem(0)
+                                }
+                            },
                             modifier = Modifier.onTapDisableSearch(),
                             staticPlaces = staticPlaces,
                             favorites = favorites,
@@ -359,7 +385,8 @@ fun HomeScreen(
                             onFilterToggle = homeViewModel::toggleFavoritesFilter,
                             onRemoveAppliedFilter = homeViewModel::removeAppliedFilter,
                             operatingHoursToString = ::isOpenAnnotatedStringFromOperatingHours,
-                            distanceStringToPlace = homeViewModel::distanceStringIfCurrentLocationExists
+                            distanceStringToPlace = homeViewModel::distanceStringIfCurrentLocationExists,
+                            listState = listStateFor(filterStateValue)
                         )
                     }
                 }