fix(player): 使用雪碧图预热首帧兜底

lib/pages/player/player_view.dart

@@ -146,7 +146,9 @@ class _PlayerPageState extends State<PlayerPage>
     _thumbnailService = PlaybackThumbnailService(
       sourceResolver: _resolveThumbnailSource,
     );
-    _spriteAxisService = SpriteThumbnailAxisService();
+    _spriteAxisService = SpriteThumbnailAxisService(
+      spriteCacheCapacity: 8,
+    )..addListener(_handleSpriteFrameChanged);
     WidgetsBinding.instance.addObserver(this);
     logic.start(
       factory: context.read<PlayerFactory>(),
@@ -266,7 +268,9 @@ class _PlayerPageState extends State<PlayerPage>
   void dispose() {
     WidgetsBinding.instance.removeObserver(this);
     appRouteObserver.unsubscribe(this);
-    _spriteAxisService.dispose();
+    _spriteAxisService
+      ..removeListener(_handleSpriteFrameChanged)
+      ..dispose();
     _thumbnailService.dispose();
     logic.dispose();
     super.dispose();
@@ -369,6 +373,30 @@ class _PlayerPageState extends State<PlayerPage>
     _chromeVisible = true;
   }
 
+  void _handleSpriteFrameChanged() {
+    if (mounted) setState(() {});
+  }
+
+  void _prewarmAdjacentThumbnails() {
+    final current = logic.session.currentIndex;
+    final indices = <int?>[
+      current,
+      logic.previousVisibleIndex(current),
+      logic.nextVisibleIndex(current),
+    ];
+    for (final index in indices) {
+      if (index == null || index < 0 || index >= logic.sessionEpisodes.length) {
+        continue;
+      }
+      final thumbnailsUrl = logic.sessionEpisodes[index].thumbnailsUrl;
+      if (thumbnailsUrl != null) {
+        unawaited(
+          _spriteAxisService.prepareAt(thumbnailsUrl, Duration.zero),
+        );
+      }
+    }
+  }
+
   void _restoreFeedChrome() {
     if (!mounted) return;
     setState(() {
@@ -451,6 +479,7 @@ class _PlayerPageState extends State<PlayerPage>
     final content = AnimatedBuilder(
       animation: logic.session,
       builder: (context, _) {
+        _prewarmAdjacentThumbnails();
         final pages = NotificationListener<ScrollNotification>(
           onNotification: _handlePageScroll,
           child: PageView.builder(
@@ -590,6 +619,15 @@ class _PlayerPageState extends State<PlayerPage>
     final videoFit = theater ? BoxFit.contain : BoxFit.cover;
     final preparedFrameAvailable =
         selected && logic.session.reusedWarmAt(index);
+    final thumbnailsUrl = episode.thumbnailsUrl;
+    final openingFrameReady =
+        thumbnailsUrl != null &&
+        _spriteAxisService.cachedFrameAt(thumbnailsUrl, Duration.zero) != null;
+    if (thumbnailsUrl != null) {
+      unawaited(
+        _spriteAxisService.prepareAt(thumbnailsUrl, Duration.zero),
+      );
+    }
     final locked = logic.session.isLocked || episode.locked;
     if (selected &&
         videoPort != null &&
@@ -617,9 +655,10 @@ class _PlayerPageState extends State<PlayerPage>
           theater: theater,
           holdOpeningUntilFirstFrame: logic.session.userWantsPlay,
           preparedFrameAvailable: preparedFrameAvailable,
+          openingFrameReady: openingFrameReady,
           openingFrame: playerOpeningFrame(
-            episode.thumbnailsUrl,
-            posterUrl: drama.posterUrl,
+            thumbnailsUrl,
+            spriteSource: _spriteAxisService,
             fit: videoFit,
           ),
         ),