Improve categories page.

lib/pages/categories_page.dart

@@ -17,39 +17,50 @@ class CategoriesPage extends StatefulWidget {
   State<CategoriesPage> createState() => _CategoriesPageState();
 }
 
-class _CategoriesPageState extends State<CategoriesPage> {
+class _CategoriesPageState extends State<CategoriesPage>
+    with
+        TickerProviderStateMixin,
+        AutomaticKeepAliveClientMixin<CategoriesPage> {
   var categories = <String>[];
 
+  late TabController controller;
+
   void onSettingsChanged() {
-    var categories =
-        List.from(appdata.settings["categories"]).whereType<String>().toList();
+    var categories = List.from(
+      appdata.settings["categories"],
+    ).whereType<String>().toList();
     var allCategories = ComicSource.all()
         .map((e) => e.categoryData?.key)
         .where((element) => element != null)
         .map((e) => e!)
         .toList();
-    categories =
-        categories.where((element) => allCategories.contains(element)).toList();
+    categories = categories
+        .where((element) => allCategories.contains(element))
+        .toList();
     if (!categories.isEqualTo(this.categories)) {
       setState(() {
         this.categories = categories;
       });
+      controller = TabController(length: categories.length, vsync: this);
     }
   }
 
   @override
   void initState() {
     super.initState();
-    var categories =
-        List.from(appdata.settings["categories"]).whereType<String>().toList();
+    var categories = List.from(
+      appdata.settings["categories"],
+    ).whereType<String>().toList();
     var allCategories = ComicSource.all()
         .map((e) => e.categoryData?.key)
         .where((element) => element != null)
         .map((e) => e!)
         .toList();
-    this.categories =
-        categories.where((element) => allCategories.contains(element)).toList();
+    this.categories = categories
+        .where((element) => allCategories.contains(element))
+        .toList();
     appdata.settings.addListener(onSettingsChanged);
+    controller = TabController(length: categories.length, vsync: this);
   }
 
   void addPage() {
@@ -59,6 +70,7 @@ class _CategoriesPageState extends State<CategoriesPage> {
   @override
   void dispose() {
     super.dispose();
+    controller.dispose();
     appdata.settings.removeListener(onSettingsChanged);
   }
 
@@ -85,46 +97,45 @@ class _CategoriesPageState extends State<CategoriesPage> {
 
   @override
   Widget build(BuildContext context) {
+    super.build(context);
     if (categories.isEmpty) {
       return buildEmpty();
     }
 
     return Material(
-      child: DefaultTabController(
-        length: categories.length,
-        key: Key(categories.toString()),
-        child: Column(
-          children: [
-            AppTabBar(
-              key: PageStorageKey(categories.toString()),
-              tabs: categories.map((e) {
-                String title = e;
-                try {
-                  title = getCategoryDataWithKey(e).title;
-                } catch (e) {
-                  //
-                }
-                return Tab(
-                  text: title,
-                  key: Key(e),
-                );
-              }).toList(),
-              actionButton: TabActionButton(
-                icon: const Icon(Icons.add),
-                text: "Add".tl,
-                onPressed: addPage,
-              ),
-            ).paddingTop(context.padding.top),
-            Expanded(
-              child: TabBarView(
-                children: categories.map((e) => _CategoryPage(e)).toList(),
-              ),
-            )
-          ],
-        ),
+      child: Column(
+        children: [
+          AppTabBar(
+            controller: controller,
+            key: PageStorageKey(categories.toString()),
+            tabs: categories.map((e) {
+              String title = e;
+              try {
+                title = getCategoryDataWithKey(e).title;
+              } catch (e) {
+                //
+              }
+              return Tab(text: title, key: Key(e));
+            }).toList(),
+            actionButton: TabActionButton(
+              icon: const Icon(Icons.add),
+              text: "Add".tl,
+              onPressed: addPage,
+            ),
+          ).paddingTop(context.padding.top),
+          Expanded(
+            child: TabBarView(
+              controller: controller,
+              children: categories.map((e) => _CategoryPage(e)).toList(),
+            ),
+          ),
+        ],
       ),
     );
   }
+
+  @override
+  bool get wantKeepAlive => true;
 }
 
 typedef ClickTagCallback = void Function(String, String?);
@@ -150,38 +161,42 @@ class _CategoryPage extends StatelessWidget {
     var children = <Widget>[];
     if (data.enableRankingPage || data.buttons.isNotEmpty) {
       children.add(buildTitle(data.title));
-      children.add(Padding(
-        padding: const EdgeInsets.fromLTRB(10, 0, 10, 16),
-        child: Wrap(
-          children: [
-            if (data.enableRankingPage)
-              buildTag("Ranking".tl, () {
-                context.to(() => RankingPage(categoryKey: data.key));
-              }),
-            for (var buttonData in data.buttons)
-              buildTag(buttonData.label.tl, buttonData.onTap)
-          ],
+      children.add(
+        Padding(
+          padding: const EdgeInsets.fromLTRB(10, 0, 10, 16),
+          child: Wrap(
+            children: [
+              if (data.enableRankingPage)
+                buildTag("Ranking".tl, () {
+                  context.to(() => RankingPage(categoryKey: data.key));
+                }),
+              for (var buttonData in data.buttons)
+                buildTag(buttonData.label.tl, buttonData.onTap),
+            ],
+          ),
         ),
-      ));
+      );
     }
 
     for (var part in data.categories) {
       if (part.enableRandom) {
-        children.add(StatefulBuilder(builder: (context, updater) {
-          return Column(
-            mainAxisSize: MainAxisSize.min,
-            crossAxisAlignment: CrossAxisAlignment.start,
-            children: [
-              buildTitleWithRefresh(part.title, () => updater(() {})),
-              buildTags(part.categories)
-            ],
-          );
-        }));
+        children.add(
+          StatefulBuilder(
+            builder: (context, updater) {
+              return Column(
+                mainAxisSize: MainAxisSize.min,
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: [
+                  buildTitleWithRefresh(part.title, () => updater(() {})),
+                  buildTags(part.categories),
+                ],
+              );
+            },
+          ),
+        );
       } else {
         children.add(buildTitle(part.title));
-        children.add(
-          buildTags(part.categories),
-        );
+        children.add(buildTags(part.categories));
       }
     }
     return SingleChildScrollView(
@@ -195,8 +210,10 @@ class _CategoryPage extends StatelessWidget {
   Widget buildTitle(String title) {
     return Padding(
       padding: const EdgeInsets.fromLTRB(16, 10, 5, 10),
-      child: Text(title.tl,
-          style: const TextStyle(fontSize: 20, fontWeight: FontWeight.w500)),
+      child: Text(
+        title.tl,
+        style: const TextStyle(fontSize: 20, fontWeight: FontWeight.w500),
+      ),
     );
   }
 
@@ -207,21 +224,16 @@ class _CategoryPage extends StatelessWidget {
         children: [
           Text(
             title.tl,
-            style: const TextStyle(
-              fontSize: 20,
-              fontWeight: FontWeight.w500,
-            ),
+            style: const TextStyle(fontSize: 20, fontWeight: FontWeight.w500),
           ),
           const Spacer(),
-          IconButton(onPressed: onRefresh, icon: const Icon(Icons.refresh))
+          IconButton(onPressed: onRefresh, icon: const Icon(Icons.refresh)),
         ],
       ),
     );
   }
 
-  Widget buildTags(
-    List<CategoryItem> categories,
-  ) {
+  Widget buildTags(List<CategoryItem> categories) {
     return Padding(
       padding: const EdgeInsets.fromLTRB(10, 0, 10, 16),
       child: Wrap(