feat(home): 支持滑动切换首页分类

lib/pages/home/widgets/home_feed_grid.dart

@@ -43,6 +43,7 @@ class HomeFeedGrid extends StatefulWidget {
 
 class _HomeFeedGridState extends State<HomeFeedGrid> {
   HomePrimaryTab _selectedPrimary = HomePrimaryTab.featured;
+  late final PageController _pageController;
   late final Map<HomePrimaryTab, ScrollController> _scrollControllers;
   final Map<HomePrimaryTab, String?> _selectedTags = {
     for (final tab in HomePrimaryTab.values) tab: null,
@@ -51,6 +52,7 @@ class _HomeFeedGridState extends State<HomeFeedGrid> {
   @override
   void initState() {
     super.initState();
+    _pageController = PageController(initialPage: _selectedPrimary.index);
     _scrollControllers = {
       for (final tab in HomePrimaryTab.values) tab: ScrollController(),
     };
@@ -58,6 +60,7 @@ class _HomeFeedGridState extends State<HomeFeedGrid> {
 
   @override
   void dispose() {
+    _pageController.dispose();
     for (final controller in _scrollControllers.values) {
       controller.dispose();
     }
@@ -93,19 +96,30 @@ class _HomeFeedGridState extends State<HomeFeedGrid> {
               tags: tags,
               selectedPrimary: _selectedPrimary,
               selectedTag: activeTag,
-              onPrimarySelected: (tab) =>
-                  setState(() => _selectedPrimary = tab),
+              onPrimarySelected: _selectPrimary,
               onTagSelected: (tag) =>
                   setState(() => _selectedTags[_selectedPrimary] = tag),
               walletBadge: walletBadge,
             ),
             Expanded(
-              child: IndexedStack(
-                index: _selectedPrimary.index,
-                children: [
-                  for (final tab in HomePrimaryTab.values)
-                    _tabGrid(context, l10n, tab: tab, shortcuts: shortcuts),
-                ],
+              child: PageView.builder(
+                key: const Key('home-primary-page-view'),
+                controller: _pageController,
+                itemCount: HomePrimaryTab.values.length,
+                onPageChanged: (index) => setState(
+                  () => _selectedPrimary = HomePrimaryTab.values[index],
+                ),
+                itemBuilder: (context, index) => _KeepAlivePage(
+                  key: PageStorageKey(
+                    'home-primary-page-${HomePrimaryTab.values[index].name}',
+                  ),
+                  child: _tabGrid(
+                    context,
+                    l10n,
+                    tab: HomePrimaryTab.values[index],
+                    shortcuts: shortcuts,
+                  ),
+                ),
               ),
             ),
           ],
@@ -114,6 +128,21 @@ class _HomeFeedGridState extends State<HomeFeedGrid> {
     );
   }
 
+  void _selectPrimary(HomePrimaryTab tab) {
+    if (tab == _selectedPrimary) return;
+    if (!_pageController.hasClients) {
+      setState(() => _selectedPrimary = tab);
+      return;
+    }
+    unawaited(
+      _pageController.animateToPage(
+        tab.index,
+        duration: AppDimens.homePrimaryTabAnimationDuration,
+        curve: Curves.easeOut,
+      ),
+    );
+  }
+
   Widget _tabGrid(
     BuildContext context,
     AppLocalizations l10n, {
@@ -329,3 +358,24 @@ class _HomeFeedGridState extends State<HomeFeedGrid> {
     );
   }
 }
+
+class _KeepAlivePage extends StatefulWidget {
+  const _KeepAlivePage({super.key, required this.child});
+
+  final Widget child;
+
+  @override
+  State<_KeepAlivePage> createState() => _KeepAlivePageState();
+}
+
+class _KeepAlivePageState extends State<_KeepAlivePage>
+    with AutomaticKeepAliveClientMixin {
+  @override
+  bool get wantKeepAlive => true;
+
+  @override
+  Widget build(BuildContext context) {
+    super.build(context);
+    return widget.child;
+  }
+}