diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/feeds/FeedContentStateView.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/feeds/FeedContentStateView.kt index fb49009cbc..abf9751322 100644 --- a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/feeds/FeedContentStateView.kt +++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/feeds/FeedContentStateView.kt @@ -63,6 +63,7 @@ fun SaveableFeedContentState( } WatchScrollToTop(feedContentState, listState) + StickToTopOnPrepend(feedContentState, listState) content(listState) } @@ -81,6 +82,7 @@ fun SaveableGridFeedContentState( } WatchScrollToTop(feedContentState, gridState) + StickToTopOnPrepend(feedContentState, gridState) content(gridState) } diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/feeds/WatchScrollToTop.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/feeds/WatchScrollToTop.kt index f7cd505d4f..8f27178ddf 100644 --- a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/feeds/WatchScrollToTop.kt +++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/feeds/WatchScrollToTop.kt @@ -26,8 +26,16 @@ import androidx.compose.foundation.pager.PagerState import androidx.compose.runtime.Composable import androidx.compose.runtime.LaunchedEffect import androidx.compose.runtime.getValue +import androidx.compose.runtime.remember +import androidx.compose.runtime.snapshotFlow import androidx.lifecycle.compose.collectAsStateWithLifecycle +import com.vitorpamplona.amethyst.commons.ui.feeds.FeedState import com.vitorpamplona.amethyst.ui.screen.loggedIn.notifications.CardFeedContentState +import kotlinx.coroutines.ExperimentalCoroutinesApi +import kotlinx.coroutines.flow.Flow +import kotlinx.coroutines.flow.flatMapLatest +import kotlinx.coroutines.flow.flowOf +import kotlinx.coroutines.flow.map @Composable fun WatchScrollToTop( @@ -88,3 +96,141 @@ fun WatchScrollToTop( } } } + +/** + * Keeps the user pinned to index 0 when new items prepend to a feed, but + * only if they were already at the very top right before the update. + * + * Why this is non-trivial: every feed uses stable `key = item.idHex` in + * its lazy list, which makes Compose preserve the visual anchor across + * data changes. When N items prepend, the user's previously-visible + * top item is still on screen but its index is now N — so + * `firstVisibleItemIndex` shifts from 0 to N without any user gesture. + * A naive `if (firstVisibleItemIndex <= 1) scrollToItem(0)` check inside + * `LaunchedEffect(items.firstOrNull())` therefore fails as soon as more + * than one item arrives in the same batch. + * + * The trick: track "was at top" continuously via [snapshotFlow], but + * only flip it from true → false when [LazyListState.isScrollInProgress] + * is true (i.e. the user is actively scrolling). Compose's keyed-item + * shift after a data update does not set that flag — only real touch + * gestures and `animate*` calls do — so data-driven index shifts can + * never poison the cached value. When [firstItemKey] changes (head of + * the list moved), if the cached value is still true, snap back to 0 + * with an instant (non-animated) scroll so the prepend appears as + * in-place growth rather than a visible jump-then-scroll. + * + * Most callers should not invoke this directly: [SaveableFeedContentState], + * [SaveableGridFeedContentState], and the analogous wrappers in + * `ui/screen/FeedView.kt` already apply auto-stick to every feed they + * own. Invoke the explicit overload only when the listState is + * constructed outside one of those wrappers, or when the key that + * should trigger the snap is not the default `items.list[0].idHex` + * (e.g. notifications, chats, or feeds keyed on something other than a + * Note's hex id). + */ +@Composable +fun StickToTopOnPrepend( + listState: LazyListState, + firstItemKey: Any?, +) { + stickToTopOnPrepend( + stateKey = listState, + firstItemKey = firstItemKey, + sampler = { + snapshotFlow { + listState.firstVisibleItemIndex == 0 && listState.firstVisibleItemScrollOffset == 0 + } + }, + isScrollInProgress = { listState.isScrollInProgress }, + firstVisibleItemIndex = { listState.firstVisibleItemIndex }, + scrollToTop = { listState.scrollToItem(0) }, + ) +} + +@Composable +fun StickToTopOnPrepend( + gridState: LazyGridState, + firstItemKey: Any?, +) { + stickToTopOnPrepend( + stateKey = gridState, + firstItemKey = firstItemKey, + sampler = { + snapshotFlow { + gridState.firstVisibleItemIndex == 0 && gridState.firstVisibleItemScrollOffset == 0 + } + }, + isScrollInProgress = { gridState.isScrollInProgress }, + firstVisibleItemIndex = { gridState.firstVisibleItemIndex }, + scrollToTop = { gridState.scrollToItem(0) }, + ) +} + +/** + * Auto-stick wired straight to a [FeedContentState]: derives the head + * key from `feedContent → Loaded.feed → list.firstOrNull()?.idHex` so + * callers don't have to collect the inner feed flow themselves. Used + * by the Saveable* wrappers; suitable for any Note-keyed feed. + */ +@Composable +fun StickToTopOnPrepend( + feedContentState: FeedContentState, + listState: LazyListState, +) { + StickToTopOnPrepend(listState, rememberFirstItemIdHex(feedContentState)) +} + +@Composable +fun StickToTopOnPrepend( + feedContentState: FeedContentState, + gridState: LazyGridState, +) { + StickToTopOnPrepend(gridState, rememberFirstItemIdHex(feedContentState)) +} + +@OptIn(ExperimentalCoroutinesApi::class) +@Composable +private fun rememberFirstItemIdHex(feedContentState: FeedContentState): String? { + val flow = + remember(feedContentState) { + feedContentState.feedContent.flatMapLatest { state -> + when (state) { + is FeedState.Loaded -> state.feed.map { it.list.firstOrNull()?.idHex } + else -> flowOf(null) + } + } + } + val key by flow.collectAsStateWithLifecycle(initialValue = null) + return key +} + +@Composable +private fun stickToTopOnPrepend( + stateKey: Any, + firstItemKey: Any?, + sampler: () -> Flow, + isScrollInProgress: () -> Boolean, + firstVisibleItemIndex: () -> Int, + scrollToTop: suspend () -> Unit, +) { + // Plain holder instead of mutableStateOf — we only read this inside + // effects, never in composition, so we don't need snapshot tracking. + val wasAtTop = remember { booleanArrayOf(true) } + + LaunchedEffect(stateKey) { + sampler().collect { atTop -> + if (atTop) { + wasAtTop[0] = true + } else if (isScrollInProgress()) { + wasAtTop[0] = false + } + } + } + + LaunchedEffect(firstItemKey) { + if (firstItemKey != null && wasAtTop[0] && firstVisibleItemIndex() > 0) { + scrollToTop() + } + } +} diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/FeedView.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/FeedView.kt index ac14f13239..7e878a2bce 100644 --- a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/FeedView.kt +++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/FeedView.kt @@ -36,6 +36,7 @@ import com.vitorpamplona.amethyst.ui.feeds.FeedError import com.vitorpamplona.amethyst.ui.feeds.FeedLoaded import com.vitorpamplona.amethyst.ui.feeds.LoadingFeed import com.vitorpamplona.amethyst.ui.feeds.RefresheableBox +import com.vitorpamplona.amethyst.ui.feeds.StickToTopOnPrepend import com.vitorpamplona.amethyst.ui.feeds.WatchScrollToTop import com.vitorpamplona.amethyst.ui.feeds.rememberForeverLazyGridState import com.vitorpamplona.amethyst.ui.feeds.rememberForeverLazyListState @@ -72,6 +73,7 @@ fun SaveableFeedState( } WatchScrollToTop(feedContentState, listState) + StickToTopOnPrepend(feedContentState, listState) content(listState) } @@ -90,6 +92,7 @@ fun SaveableGridFeedState( } WatchScrollToTop(viewModel.feedState, gridState) + StickToTopOnPrepend(viewModel.feedState, gridState) content(gridState) } diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/UserFeedView.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/UserFeedView.kt index 9b7a5895b4..1d0edc75ea 100644 --- a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/UserFeedView.kt +++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/UserFeedView.kt @@ -35,6 +35,7 @@ import com.vitorpamplona.amethyst.ui.feeds.FeedEmpty import com.vitorpamplona.amethyst.ui.feeds.FeedError import com.vitorpamplona.amethyst.ui.feeds.LoadingFeed import com.vitorpamplona.amethyst.ui.feeds.RefresheableBox +import com.vitorpamplona.amethyst.ui.feeds.StickToTopOnPrepend import com.vitorpamplona.amethyst.ui.layouts.rememberFeedContentPadding import com.vitorpamplona.amethyst.ui.navigation.navs.INav import com.vitorpamplona.amethyst.ui.note.UserCompose @@ -90,6 +91,8 @@ private fun FeedLoaded( val items by state.feed.collectAsStateWithLifecycle() val listState = rememberLazyListState() + StickToTopOnPrepend(listState, items.firstOrNull()?.pubkeyHex) + LazyColumn( modifier = Modifier.fillMaxSize(), contentPadding = rememberFeedContentPadding(FeedPadding), diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/emojipacks/browse/BrowseEmojiSetsScreen.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/emojipacks/browse/BrowseEmojiSetsScreen.kt index 22f686f50b..28e434854b 100644 --- a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/emojipacks/browse/BrowseEmojiSetsScreen.kt +++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/emojipacks/browse/BrowseEmojiSetsScreen.kt @@ -44,6 +44,7 @@ import com.vitorpamplona.amethyst.ui.feeds.FeedError import com.vitorpamplona.amethyst.ui.feeds.LoadingFeed import com.vitorpamplona.amethyst.ui.feeds.RefresheableBox import com.vitorpamplona.amethyst.ui.feeds.ScrollStateKeys +import com.vitorpamplona.amethyst.ui.feeds.StickToTopOnPrepend import com.vitorpamplona.amethyst.ui.feeds.WatchLifecycleAndUpdateModel import com.vitorpamplona.amethyst.ui.feeds.WatchScrollToTop import com.vitorpamplona.amethyst.ui.feeds.rememberForeverLazyGridState @@ -157,6 +158,8 @@ private fun BrowseEmojiSetsGridLoaded( ) { val items by loaded.feed.collectAsStateWithLifecycle() + StickToTopOnPrepend(gridState, items.list.firstOrNull()?.idHex) + LazyVerticalGrid( columns = GridCells.Adaptive(minSize = 160.dp), state = gridState, diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/notifications/CardFeedView.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/notifications/CardFeedView.kt index 248ade8d97..4c4fd18d4a 100644 --- a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/notifications/CardFeedView.kt +++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/notifications/CardFeedView.kt @@ -58,6 +58,7 @@ import com.vitorpamplona.amethyst.commons.ui.notifications.CardFeedState import com.vitorpamplona.amethyst.logTime import com.vitorpamplona.amethyst.ui.feeds.FeedError import com.vitorpamplona.amethyst.ui.feeds.LoadingFeed +import com.vitorpamplona.amethyst.ui.feeds.StickToTopOnPrepend import com.vitorpamplona.amethyst.ui.layouts.rememberFeedContentPadding import com.vitorpamplona.amethyst.ui.navigation.navs.INav import com.vitorpamplona.amethyst.ui.note.BadgeCompose @@ -151,6 +152,8 @@ private fun FeedLoaded( val items by loaded.feed.collectAsStateWithLifecycle() val openPolls by polls.flow.collectAsStateWithLifecycle() + StickToTopOnPrepend(listState, items.list.firstOrNull()?.id()) + // Track which card is highlighted (will auto-clear after animation) var highlightedCardId by remember { mutableStateOf(null) } diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/profile/newthreads/TabNotesNewThreads.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/profile/newthreads/TabNotesNewThreads.kt index 9b256d96ff..5353327843 100644 --- a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/profile/newthreads/TabNotesNewThreads.kt +++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/profile/newthreads/TabNotesNewThreads.kt @@ -40,6 +40,7 @@ import com.vitorpamplona.amethyst.ui.feeds.FeedEmpty import com.vitorpamplona.amethyst.ui.feeds.FeedError import com.vitorpamplona.amethyst.ui.feeds.LoadingFeed import com.vitorpamplona.amethyst.ui.feeds.RefresheableBox +import com.vitorpamplona.amethyst.ui.feeds.StickToTopOnPrepend import com.vitorpamplona.amethyst.ui.feeds.WatchScrollToTop import com.vitorpamplona.amethyst.ui.navigation.navs.INav import com.vitorpamplona.amethyst.ui.note.NoteCompose @@ -133,6 +134,11 @@ private fun FeedLoadedWithPinnedNotes( state } + StickToTopOnPrepend( + listState, + pinnedItems?.list?.firstOrNull()?.idHex ?: feedItems?.list?.firstOrNull()?.idHex, + ) + LazyColumn( contentPadding = FeedPadding, state = listState,