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fix: library grid stuck skeletons on fast scroll

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This commit is contained in:
edde746
2026-03-25 06:35:01 +01:00
parent 23043c61f4
commit 4beeedd318
1 changed files with 53 additions and 24 deletions
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lib/screens/libraries/tabs/library_browse_tab.dart
+53 -24
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@@ -208,6 +208,10 @@ class _LibraryBrowseTabState extends BaseLibraryTabState<PlexMetadata, LibraryBr
int _firstCharactersRequestId = 0;
static const int _fetchSize = 200;
Timer? _scrollIdleTimer;
Timer? _retryTimer;
int _retryCount = 0;
bool _rangeLoadScheduled = false;
bool _visibleRangeLoading = false;
// Focus nodes for filter chips
final FocusNode _groupingChipFocusNode = FocusNode(debugLabel: 'grouping_chip');
@@ -226,6 +230,7 @@ class _LibraryBrowseTabState extends BaseLibraryTabState<PlexMetadata, LibraryBr
@override
void dispose() {
_cancelToken?.cancel();
_retryTimer?.cancel();
_scrollActivityTimer?.cancel();
_scrollIdleTimer?.cancel();
_alphaUpdateTimer?.cancel();
@@ -347,6 +352,7 @@ class _LibraryBrowseTabState extends BaseLibraryTabState<PlexMetadata, LibraryBr
Future<void> _loadContent() async {
// Cancel any pending request
_cancelToken?.cancel();
_retryTimer?.cancel();
_cancelToken = CancelToken();
// Use a generation counter for the filter/sort loading phase
final generation = ++_requestId;
@@ -451,6 +457,7 @@ class _LibraryBrowseTabState extends BaseLibraryTabState<PlexMetadata, LibraryBr
Future<void> _loadItems() async {
final currentRequestId = ++_requestId;
_cancelToken?.cancel();
_retryTimer?.cancel();
_cancelToken = CancelToken();
setState(() {
@@ -506,15 +513,15 @@ class _LibraryBrowseTabState extends BaseLibraryTabState<PlexMetadata, LibraryBr
/// Fetch a range of items from the API and store them in the sparse map.
/// After a successful fetch, re-checks for remaining gaps in the visible range.
Future<void> _fetchRange(int start, int size) async {
Future<bool> _fetchRange(int start, int size) async {
// Clamp to totalSize
if (start >= _totalSize) return;
if (start >= _totalSize) return false;
final clampedSize = size.clamp(0, _totalSize - start);
if (clampedSize == 0) return;
if (clampedSize == 0) return false;
// Deduplicate: track every index in-flight to prevent overlapping fetches
final indices = List.generate(clampedSize, (i) => start + i);
if (indices.every((i) => _loadingRanges.contains(i) || _loadedItems.containsKey(i))) return;
if (indices.every((i) => _loadingRanges.contains(i) || _loadedItems.containsKey(i))) return true;
_loadingRanges.addAll(indices);
final currentRequestId = _requestId;
@@ -531,31 +538,31 @@ class _LibraryBrowseTabState extends BaseLibraryTabState<PlexMetadata, LibraryBr
cancelToken: _cancelToken,
);
if (currentRequestId != _requestId || !mounted) return;
if (currentRequestId != _requestId || !mounted) return false;
setState(() {
for (var i = 0; i < result.items.length; i++) {
_loadedItems[start + i] = result.items[i];
}
// Update totalSize in case it changed (e.g., items added/removed on server)
if (result.totalSize != _totalSize) {
_totalSize = result.totalSize;
}
});
// Prefetch images for items about to enter the viewport
_retryCount = 0;
_prefetchImages(start, result.items);
// Re-check for remaining gaps in the visible range after this fetch
WidgetsBinding.instance.addPostFrameCallback((_) {
return true;
} catch (e) {
if (e is DioException && e.type == DioExceptionType.cancel) return false;
_retryCount++;
final delay = Duration(milliseconds: 500 * (1 << _retryCount.clamp(0, 4)));
_retryTimer?.cancel();
_retryTimer = Timer(delay, () {
if (mounted && currentRequestId == _requestId) {
_loadVisibleRange();
}
});
} catch (e) {
// Silently ignore fetch errors for background range loads
// (the initial load handles errors with UI feedback)
if (e is DioException && e.type == DioExceptionType.cancel) return;
return false;
} finally {
_loadingRanges.removeAll(indices);
}
@@ -892,6 +899,9 @@ class _LibraryBrowseTabState extends BaseLibraryTabState<PlexMetadata, LibraryBr
_scrollIdleTimer?.cancel();
_scrollIdleTimer = Timer(const Duration(milliseconds: 200), () {
if (!mounted) return;
// Discard stale in-flight tracking from eager prefetch during scroll
// so _loadVisibleRange sees the full gap at the settled position.
_loadingRanges.clear();
_loadVisibleRange();
_evictDistantItems();
final firstVisible = _itemIndexFromScrollOffset(_scrollController.offset);
@@ -1089,10 +1099,23 @@ class _LibraryBrowseTabState extends BaseLibraryTabState<PlexMetadata, LibraryBr
);
}
/// Self-healing: when a skeleton is rendered after scrolling stops,
/// ensure the visible range gets loaded even if the scroll-idle path missed it.
void _scheduleRangeLoad() {
if (_rangeLoadScheduled || _isScrollActive) return;
_rangeLoadScheduled = true;
WidgetsBinding.instance.addPostFrameCallback((_) {
_rangeLoadScheduled = false;
if (mounted) _loadVisibleRange();
});
}
/// Determine the visible range and fetch any unloaded items within it.
/// Covers the full visible area plus a buffer of _fetchSize/2 on each side,
/// then finds the first unloaded contiguous block and fetches it.
void _loadVisibleRange() {
/// Serialized: only one visible-range fetch runs at a time to prevent
/// concurrent calls from seeing each other's _loadingRanges and producing
/// tiny fetch sizes.
Future<void> _loadVisibleRange() async {
if (_visibleRangeLoading) return;
if (_totalSize == 0 || _currentColumnCount < 1 || !_scrollController.hasClients) return;
if (_lastCrossAxisExtent <= 0) return;
@@ -1100,7 +1123,6 @@ class _LibraryBrowseTabState extends BaseLibraryTabState<PlexMetadata, LibraryBr
final viewportHeight = _scrollController.position.viewportDimension;
final firstIndex = _itemIndexFromScrollOffset(offset);
// Calculate how many items fit in the viewport
final itemWidth = _lastCrossAxisExtent / _currentColumnCount;
final itemHeight = itemWidth / GridLayoutConstants.posterAspectRatio;
final rowHeight = itemHeight + GridLayoutConstants.mainAxisSpacing;
@@ -1109,12 +1131,10 @@ class _LibraryBrowseTabState extends BaseLibraryTabState<PlexMetadata, LibraryBr
final visibleRows = (viewportHeight / rowHeight).ceil() + 1;
final visibleCount = visibleRows * _currentColumnCount;
// Expand the visible range by a buffer on each side
final buffer = _fetchSize ~/ 2;
final rangeStart = (firstIndex - buffer).clamp(0, _totalSize);
final rangeEnd = (firstIndex + visibleCount + buffer).clamp(0, _totalSize);
// Find the first and last unloaded indices in the range
int? fetchStart;
int? fetchEnd;
for (var i = rangeStart; i < rangeEnd; i++) {
@@ -1125,10 +1145,18 @@ class _LibraryBrowseTabState extends BaseLibraryTabState<PlexMetadata, LibraryBr
}
if (fetchStart == null || fetchEnd == null) return;
final fetchSize = fetchEnd - fetchStart;
if (fetchSize <= 0) return;
_fetchRange(fetchStart, fetchSize);
_retryTimer?.cancel();
_visibleRangeLoading = true;
try {
final success = await _fetchRange(fetchStart, fetchEnd - fetchStart);
if (success && mounted) {
WidgetsBinding.instance.addPostFrameCallback((_) {
if (mounted) _loadVisibleRange();
});
}
} finally {
_visibleRangeLoading = false;
}
}
/// Eagerly prefetch data when approaching unloaded boundaries during scroll.
@@ -1450,6 +1478,7 @@ class _LibraryBrowseTabState extends BaseLibraryTabState<PlexMetadata, LibraryBr
// Show skeleton placeholder for unloaded items
if (item == null) {
_scheduleRangeLoad();
return _SkeletonCard(animate: !_isScrollActive);
}