feat(player): 增加进度条拖动画面预览

lib/pages/player/player_view.dart

@@ -6,6 +6,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:provider/provider.dart';
 
+import '../../core/config/app_config.dart';
 import '../../core/data/models/drama.dart';
 import '../../core/data/repositories/comment_repository.dart';
 import '../../core/data/services/favorite_controller.dart';
@@ -13,6 +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/playback_thumbnail_service.dart';
 import '../../core/data/services/video_player_port.dart';
 import '../../core/data/services/wallet_controller.dart';
 import '../../core/formatting/error_text.dart';
@@ -103,6 +105,7 @@ class PlayerPage extends StatefulWidget {
 class _PlayerPageState extends State<PlayerPage>
     with WidgetsBindingObserver, RouteAware {
   late final PlayerLogic logic;
+  late final PlaybackThumbnailService _thumbnailService;
   PageRoute<dynamic>? _subscribedRoute;
   bool _chromeVisible = true;
   double _playbackSpeed = 1.0;
@@ -125,6 +128,9 @@ class _PlayerPageState extends State<PlayerPage>
       downloads: widget.downloads,
     );
     logic.attach(widget, isMounted: () => mounted);
+    _thumbnailService = PlaybackThumbnailService(
+      sourceResolver: _resolveThumbnailSource,
+    );
     WidgetsBinding.instance.addObserver(this);
     logic.start(
       factory: context.read<PlayerFactory>(),
@@ -161,6 +167,57 @@ class _PlayerPageState extends State<PlayerPage>
   String _feedSignature(List<Drama>? dramas) =>
       dramas == null ? '' : dramas.map((drama) => drama.id).join('|');
 
+  PlaybackThumbnailSource? _resolveThumbnailSource(String episodeId) {
+    final localPath = widget.downloads?.localPathFor(episodeId);
+    Episode? episode;
+    for (final item in logic.sessionEpisodes) {
+      if (item.id == episodeId) {
+        episode = item;
+        break;
+      }
+    }
+    if (localPath != null && localPath.isNotEmpty) {
+      return PlaybackThumbnailSource(localPath: localPath);
+    }
+    final rawUrl = episode?.videoUrl ?? '';
+    final active = logic.session.active;
+    final activeSource = active is VideoPlayerPort
+        ? active.controller.dataSource
+        : '';
+    final currentEpisodeId = logic.sessionEpisodes.isEmpty
+        ? null
+        : logic.session.currentEpisode.id;
+    final activeMatches =
+        currentEpisodeId == episodeId && activeSource.isNotEmpty;
+    if (activeMatches && activeSource.startsWith('file:')) {
+      try {
+        return PlaybackThumbnailSource(
+          localPath: Uri.parse(activeSource).toFilePath(),
+        );
+      } catch (_) {
+        return null;
+      }
+    }
+    if (rawUrl.startsWith('file:')) {
+      try {
+        return PlaybackThumbnailSource(
+          localPath: Uri.parse(rawUrl).toFilePath(),
+        );
+      } catch (_) {
+        return null;
+      }
+    }
+    final remoteUrl = AppConfig.mediaUrl(
+      rawUrl.isNotEmpty
+          ? rawUrl
+          : activeMatches
+          ? activeSource
+          : '',
+    );
+    if (remoteUrl.isEmpty) return null;
+    return PlaybackThumbnailSource(remoteUrl: remoteUrl);
+  }
+
   @override
   void didChangeDependencies() {
     super.didChangeDependencies();
@@ -190,6 +247,7 @@ class _PlayerPageState extends State<PlayerPage>
   void dispose() {
     WidgetsBinding.instance.removeObserver(this);
     appRouteObserver.unsubscribe(this);
+    _thumbnailService.dispose();
     logic.dispose();
     super.dispose();
   }
@@ -547,6 +605,7 @@ class _PlayerPageState extends State<PlayerPage>
             onSeek: ready
                 ? (position) => logic.seekTo(context, videoPort!, position)
                 : null,
+            thumbnailService: _thumbnailService,
           )
         else
           PlayerPlaybackOverlay(
@@ -569,6 +628,7 @@ class _PlayerPageState extends State<PlayerPage>
               playbackSpeed: _playbackSpeed,
               totalEpisodes: logic.visibleIndices.length,
               boosting: _boosting,
+              thumbnailService: _thumbnailService,
             ),
             actions: PlayerOverlayActions(
               onBack: widget.embedded