feat(recommend): 支持横向切换三个内容页

lib/pages/recommend/recommend_page.dart

@@ -38,8 +38,15 @@ class RecommendPage extends StatefulWidget {
 
 class _RecommendPageState extends State<RecommendPage> {
   RecommendInnerTab _tab = RecommendInnerTab.feed;
+  final PageController _pageController = PageController();
   int _scrubCancelRequest = 0;
 
+  @override
+  void dispose() {
+    _pageController.dispose();
+    super.dispose();
+  }
+
   @override
   Widget build(BuildContext context) {
     final categories = context.read<CategoryController>();
@@ -51,23 +58,35 @@ class _RecommendPageState extends State<RecommendPage> {
           Positioned.fill(
             child: ListenableBuilder(
               listenable: Listenable.merge([widget.feedController, categories]),
-              builder: (context, _) => IndexedStack(
-                index: _tab.index,
+              builder: (context, _) => PageView(
+                key: const Key('recommend-tab-page-view'),
+                controller: _pageController,
+                scrollDirection: Axis.horizontal,
+                onPageChanged: _onPageChanged,
                 children: [
-                  _recommendFeed(context),
-                  _withTopNavSpace(
-                    RecommendSectionsView(
-                      feedController: widget.feedController,
-                      categories: categories,
-                      onOpenDrama: _openDrama,
-                      onMore: _handleMore,
+                  _KeepAliveTab(
+                    key: const PageStorageKey('recommend-tab-feed'),
+                    child: _recommendFeed(context),
+                  ),
+                  _KeepAliveTab(
+                    key: const PageStorageKey('recommend-tab-playlists'),
+                    child: _withTopNavSpace(
+                      RecommendSectionsView(
+                        feedController: widget.feedController,
+                        categories: categories,
+                        onOpenDrama: _openDrama,
+                        onMore: _handleMore,
+                      ),
                     ),
                   ),
-                  _withTopNavSpace(
-                    AllDramasFilterGrid(
-                      feedController: widget.feedController,
-                      onOpenDrama: _openDrama,
-                      onOpenFilter: widget.onOpenFilter,
+                  _KeepAliveTab(
+                    key: const PageStorageKey('recommend-tab-all'),
+                    child: _withTopNavSpace(
+                      AllDramasFilterGrid(
+                        feedController: widget.feedController,
+                        onOpenDrama: _openDrama,
+                        onOpenFilter: widget.onOpenFilter,
+                      ),
                     ),
                   ),
                 ],
@@ -162,6 +181,24 @@ class _RecommendPageState extends State<RecommendPage> {
       _tab = tab;
       _scrubCancelRequest++;
     });
+    if (_pageController.hasClients) {
+      unawaited(
+        _pageController.animateToPage(
+          tab.index,
+          duration: const Duration(milliseconds: 220),
+          curve: Curves.easeOut,
+        ),
+      );
+    }
+  }
+
+  void _onPageChanged(int index) {
+    final next = RecommendInnerTab.values[index];
+    if (next == _tab) return;
+    setState(() {
+      _tab = next;
+      _scrubCancelRequest++;
+    });
   }
 
   void _handleSearch() {
@@ -180,10 +217,31 @@ class _RecommendPageState extends State<RecommendPage> {
   }
 
   void _handleMore(RecommendSectionKind section) {
-    setState(() => _tab = RecommendInnerTab.allDramas);
+    _selectTab(RecommendInnerTab.allDramas);
   }
 
   Future<void> _openDrama(Drama drama, {String? episodeId}) async {
     await playDramaFromCatalog(context, drama, episodeId: episodeId);
   }
 }
+
+class _KeepAliveTab extends StatefulWidget {
+  const _KeepAliveTab({super.key, required this.child});
+
+  final Widget child;
+
+  @override
+  State<_KeepAliveTab> createState() => _KeepAliveTabState();
+}
+
+class _KeepAliveTabState extends State<_KeepAliveTab>
+    with AutomaticKeepAliveClientMixin<_KeepAliveTab> {
+  @override
+  bool get wantKeepAlive => true;
+
+  @override
+  Widget build(BuildContext context) {
+    super.build(context);
+    return widget.child;
+  }
+}