feat(player): 进度条拖动预览改用雪碧图

lib/pages/player/player_view.dart

@@ -14,6 +14,7 @@ import '../../core/data/services/download_controller.dart';
 import '../../core/data/services/interaction_controller.dart';
 import '../../core/data/services/playback_position_cache.dart';
 import '../../core/data/services/playback_session.dart';
+import '../../core/data/services/sprite_thumbnail_axis.dart';
 import '../../core/data/services/playback_thumbnail_service.dart';
 import '../../core/data/services/video_player_port.dart';
 import '../../core/data/services/wallet_controller.dart';
@@ -106,6 +107,7 @@ class _PlayerPageState extends State<PlayerPage>
     with WidgetsBindingObserver, RouteAware {
   late final PlayerLogic logic;
   late final PlaybackThumbnailService _thumbnailService;
+  late final SpriteThumbnailAxisService _spriteAxisService;
   PageRoute<dynamic>? _subscribedRoute;
   bool _chromeVisible = true;
   double _playbackSpeed = 1.0;
@@ -131,6 +133,7 @@ class _PlayerPageState extends State<PlayerPage>
     _thumbnailService = PlaybackThumbnailService(
       sourceResolver: _resolveThumbnailSource,
     );
+    _spriteAxisService = SpriteThumbnailAxisService();
     WidgetsBinding.instance.addObserver(this);
     logic.start(
       factory: context.read<PlayerFactory>(),
@@ -247,6 +250,7 @@ class _PlayerPageState extends State<PlayerPage>
   void dispose() {
     WidgetsBinding.instance.removeObserver(this);
     appRouteObserver.unsubscribe(this);
+    _spriteAxisService.dispose();
     _thumbnailService.dispose();
     logic.dispose();
     super.dispose();
@@ -422,9 +426,12 @@ class _PlayerPageState extends State<PlayerPage>
     final l10n = AppLocalizations.of(context)!;
     final entry = logic.queue.entryAt(index);
     final drama = entry.drama;
-    final episode = widget.homeMode
-        ? logic.displayEpisode(drama, entry.episode)
+    final sessionEpisode = index >= 0 && index < logic.sessionEpisodes.length
+        ? logic.sessionEpisodes[index]
         : entry.episode;
+    final episode = widget.homeMode
+        ? logic.displayEpisode(drama, sessionEpisode)
+        : sessionEpisode;
     final selected = index == logic.session.currentIndex;
     // Selection changes before the prepared slot is promoted. Use its controller
     // throughout the handoff instead of briefly falling back to a placeholder.
@@ -435,6 +442,14 @@ class _PlayerPageState extends State<PlayerPage>
     final ready = videoPort?.controller.value.isInitialized ?? false;
     final theater = logic.pip || logic.pipPreparing;
     final locked = logic.session.isLocked || episode.locked;
+    if (selected && ready) {
+      unawaited(
+        _spriteAxisService.prepareAt(
+          episode.thumbnailsUrl,
+          videoPort!.controller.value.position,
+        ),
+      );
+    }
 
     return Stack(
       fit: StackFit.expand,
@@ -606,6 +621,7 @@ class _PlayerPageState extends State<PlayerPage>
                 ? (position) => logic.seekTo(context, videoPort!, position)
                 : null,
             thumbnailService: _thumbnailService,
+            spriteAxisService: _spriteAxisService,
           )
         else
           PlayerPlaybackOverlay(
@@ -629,6 +645,7 @@ class _PlayerPageState extends State<PlayerPage>
               totalEpisodes: logic.visibleIndices.length,
               boosting: _boosting,
               thumbnailService: _thumbnailService,
+              spriteAxisService: _spriteAxisService,
             ),
             actions: PlayerOverlayActions(
               onBack: widget.embedded