feat: 列表滑动预加载

app/src/main/java/com/huanchengfly/tieba/post/ui/page/forum/threadlist/ForumThreadListPage.kt

@@ -347,7 +347,9 @@ fun ForumThreadListPage(
                     )
                 )
             },
-            loadEnd = !hasMore
+            loadEnd = !hasMore,
+            lazyListState = lazyListState,
+            isEmpty = threadList.isEmpty(),
         ) {
             ThreadList(
                 state = lazyListState,

app/src/main/java/com/huanchengfly/tieba/post/ui/page/history/list/HistoryListPage.kt

@@ -10,6 +10,7 @@ import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
+import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.material.DropdownMenuItem
 import androidx.compose.material.Text
 import androidx.compose.runtime.Composable
@@ -94,6 +95,7 @@ fun HistoryListPage(
     viewModel.onEvent<HistoryListUiEvent.Delete.Success> {
         snackbarHostState.showSnackbar(context.getString(R.string.delete_history_success))
     }
+    val lazyListState = rememberLazyListState()
     Box(
         modifier = Modifier
             .fillMaxSize()
@@ -101,9 +103,15 @@ fun HistoryListPage(
         LoadMoreLayout(
             isLoading = isLoadingMore,
             onLoadMore = { viewModel.send(HistoryListUiIntent.LoadMore(currentPage + 1)) },
-            loadEnd = !hasMore
+            loadEnd = !hasMore,
+            lazyListState = lazyListState,
+            isEmpty = todayHistoryData.isEmpty() && beforeHistoryData.isEmpty()
         ) {
-            LazyColumn {
+            LazyColumn(
+                modifier = Modifier
+                    .fillMaxSize(),
+                state = lazyListState
+            ) {
                 if (todayHistoryData.isNotEmpty()) {
                     stickyHeader(key = "TodayHistoryHeader") {
                         Column(

app/src/main/java/com/huanchengfly/tieba/post/ui/page/main/explore/concern/ConcernPage.kt

@@ -78,7 +78,8 @@ fun ConcernPage(
     ) {
         LoadMoreLayout(
             isLoading = isLoadingMore,
-            onLoadMore = { viewModel.send(ConcernUiIntent.LoadMore(nextPageTag)) }
+            onLoadMore = { viewModel.send(ConcernUiIntent.LoadMore(nextPageTag)) },
+            lazyListState = lazyListState,
         ) {
             val windowSizeClass = BaseComposeActivity.LocalWindowSizeClass.current
             val itemFraction = when (windowSizeClass.widthSizeClass) {

app/src/main/java/com/huanchengfly/tieba/post/ui/page/main/explore/personalized/PersonalizedPage.kt

@@ -36,6 +36,7 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableIntStateOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberUpdatedState
@@ -113,7 +114,7 @@ fun PersonalizedPage(
     val lazyListState = rememberLazyListState()
     viewModel.bindScrollToTopEvent(lazyListState = lazyListState)
     var refreshCount by remember {
-        mutableStateOf(0)
+        mutableIntStateOf(0)
     }
     var showRefreshTip by remember {
         mutableStateOf(false)
@@ -150,8 +151,10 @@ fun PersonalizedPage(
     Box(modifier = Modifier.pullRefresh(pullRefreshState)) {
         LoadMoreLayout(
             isLoading = isLoadingMore,
-            loadEnd = false,
             onLoadMore = { viewModel.send(PersonalizedUiIntent.LoadMore(currentPage + 1)) },
+            loadEnd = false,
+            lazyListState = lazyListState,
+            isEmpty = data.isEmpty()
         ) {
             FeedList(
                 state = lazyListState,

app/src/main/java/com/huanchengfly/tieba/post/ui/page/main/notifications/list/NotificationsListPage.kt

@@ -10,6 +10,7 @@ import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
+import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material.ExperimentalMaterialApi
 import androidx.compose.material.Text
@@ -80,17 +81,21 @@ fun NotificationsListPage(
     )
     val pullRefreshState = rememberPullRefreshState(
         refreshing = isRefreshing,
-        onRefresh = { viewModel.send(NotificationsListUiIntent.Refresh) })
+        onRefresh = { viewModel.send(NotificationsListUiIntent.Refresh) }
+    )
+    val lazyListState = rememberLazyListState()
     Box(
         modifier = Modifier.pullRefresh(pullRefreshState)
     ) {
         LoadMoreLayout(
             isLoading = isLoadingMore,
-            loadEnd = !hasMore,
             onLoadMore = { viewModel.send(NotificationsListUiIntent.LoadMore(currentPage + 1)) },
+            loadEnd = !hasMore,
+            lazyListState = lazyListState,
         ) {
             LazyColumn(
-                contentPadding = PaddingValues(vertical = 4.dp)
+                contentPadding = PaddingValues(vertical = 4.dp),
+                state = lazyListState,
             ) {
                 items(
                     items = data,

app/src/main/java/com/huanchengfly/tieba/post/ui/page/subposts/SubPostsPage.kt

@@ -354,7 +354,6 @@ internal fun SubPostsContent(
         ) { paddingValues ->
             LoadMoreLayout(
                 isLoading = isLoading,
-                loadEnd = !hasMore,
                 onLoadMore = {
                     viewModel.send(
                         SubPostsUiIntent.LoadMore(
@@ -365,7 +364,10 @@ internal fun SubPostsContent(
                             currentPage + 1,
                         )
                     )
-                }
+                },
+                loadEnd = !hasMore,
+                lazyListState = lazyListState,
+                isEmpty = post == null && subPosts.isEmpty(),
             ) {
                 LazyColumn(
                     modifier = Modifier.padding(paddingValues),

app/src/main/java/com/huanchengfly/tieba/post/ui/page/thread/ThreadPage.kt

@@ -1114,7 +1114,6 @@ fun ThreadPage(
                         ) {
                             LoadMoreLayout(
                                 isLoading = isLoadingMore,
-                                loadEnd = !hasMore,
                                 onLoadMore = {
                                     viewModel.send(
                                         ThreadUiIntent.LoadMore(
@@ -1128,7 +1127,10 @@ fun ThreadPage(
                                             postIds = data.map { it.post.get { id } }
                                         )
                                     )
-                                }
+                                },
+                                loadEnd = !hasMore,
+                                lazyListState = lazyListState,
+                                isEmpty = firstPost == null && data.isEmpty()
                             ) {
                                 LazyColumn(
                                     state = lazyListState,

app/src/main/java/com/huanchengfly/tieba/post/ui/page/threadstore/ThreadStorePage.kt

@@ -8,6 +8,7 @@ import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
+import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.foundation.text.InlineTextContent
 import androidx.compose.foundation.text.appendInlineContent
@@ -157,13 +158,16 @@ fun ThreadStorePage(
                 onRefresh = { viewModel.send(ThreadStoreUiIntent.Refresh) }
             )
 
+            val lazyListState = rememberLazyListState()
+
             Box(modifier = Modifier.pullRefresh(pullRefreshState)) {
                 LoadMoreLayout(
                     isLoading = isLoadingMore,
                     onLoadMore = { viewModel.send(ThreadStoreUiIntent.LoadMore(currentPage + 1)) },
-                    loadEnd = !hasMore
+                    loadEnd = !hasMore,
+                    lazyListState = lazyListState
                 ) {
-                    LazyColumn {
+                    LazyColumn(state = lazyListState) {
                         items(
                             items = data,
                             key = { it.threadId }

app/src/main/java/com/huanchengfly/tieba/post/ui/widgets/compose/LoadMore.kt

@@ -12,6 +12,7 @@ import androidx.compose.foundation.layout.offset
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.lazy.LazyListState
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material.CircularProgressIndicator
 import androidx.compose.material.ExperimentalMaterialApi
@@ -23,11 +24,13 @@ import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableLongStateOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.rememberUpdatedState
 import androidx.compose.runtime.setValue
+import androidx.compose.runtime.snapshotFlow
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.geometry.Offset
@@ -45,6 +48,7 @@ import com.huanchengfly.tieba.post.ui.common.theme.compose.loadMoreIndicator
 import kotlinx.coroutines.FlowPreview
 import kotlinx.coroutines.channels.BufferOverflow
 import kotlinx.coroutines.flow.MutableSharedFlow
+import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.flow.sample
 import kotlinx.coroutines.launch
 import kotlin.math.abs
@@ -66,12 +70,15 @@ fun LoadMoreLayout(
             willLoad = willLoad
         )
     },
-    content: @Composable () -> Unit
+    lazyListState: LazyListState? = null,
+    isEmpty: Boolean = lazyListState?.layoutInfo?.totalItemsCount == 0,
+    preloadCount: Int = 1,
+    content: @Composable () -> Unit,
 ) {
     val loadDistance = with(LocalDensity.current) { LoadDistance.toPx() }
 
     val curOnLoadMore by rememberUpdatedState(newValue = onLoadMore)
-    var lastTriggerTime by remember { mutableStateOf(0L) }
+    var lastTriggerTime by remember { mutableLongStateOf(0L) }
     var waitingStateReset by remember { mutableStateOf(false) }
     val loadMoreFlow = remember {
         MutableSharedFlow<Long>(
@@ -95,9 +102,32 @@ fun LoadMoreLayout(
     }
 
     val canLoadMore = remember(enableLoadMore, loadEnd) { enableLoadMore && !loadEnd }
+    val curIsEmpty by rememberUpdatedState(newValue = isEmpty)
     val curIsLoading by rememberUpdatedState(newValue = isLoading)
     val curCanLoadMore by rememberUpdatedState(newValue = canLoadMore)
 
+    // 处理列表滚动到底部时自动加载更多
+    val curLazyListState by rememberUpdatedState(newValue = lazyListState)
+    LaunchedEffect(curLazyListState) {
+        curLazyListState?.let { state ->
+            snapshotFlow {
+                val shouldPreload = !curIsEmpty && curCanLoadMore && !curIsLoading
+                val isInPreloadRange =
+                    state.firstVisibleItemIndex + state.layoutInfo.visibleItemsInfo.size - 1 >= state.layoutInfo.totalItemsCount - preloadCount
+                shouldPreload && isInPreloadRange
+            }
+                .distinctUntilChanged()
+                .collect {
+                    if (it) {
+                        val curTime = System.currentTimeMillis()
+                        coroutineScope.launch {
+                            loadMoreFlow.emit(curTime)
+                        }
+                        curTime - lastTriggerTime >= 500
+                    }
+                }
+        }
+    }
 
     val swipeableState = rememberSwipeableState(false) { newValue ->
         if (newValue && !curIsLoading && curCanLoadMore) {
@@ -116,7 +146,7 @@ fun LoadMoreLayout(
         }
     }
 
-    LaunchedEffect(isLoading) { swipeableState.animateTo(isLoading) }
+    LaunchedEffect(isLoading) { if (!isLoading) swipeableState.animateTo(isLoading) }
 
     Box(
         modifier = Modifier