add gui animation setting

lib/basic/config/GuiAnimation.dart

@@ -0,0 +1,42 @@
+/// 自动全屏
+
+import 'package:flutter/material.dart';
+
+import '../Common.dart';
+import '../Method.dart';
+
+const _propertyName = "guiAnimation";
+late bool _guiAnimation;
+
+Future<void> initGuiAnimation() async {
+  _guiAnimation = (await method.loadProperty(_propertyName, "true")) == "true";
+}
+
+bool currentGuiAnimation() {
+  return _guiAnimation;
+}
+
+Future<void> _chooseGuiAnimation(BuildContext context) async {
+  String? result =
+      await chooseListDialog<String>(context, "进入阅读器自动全屏", ["是", "否"]);
+  if (result != null) {
+    var target = result == "是";
+    await method.saveProperty(_propertyName, "$target");
+    _guiAnimation = target;
+  }
+}
+
+Widget guiAnimationSetting() {
+  return StatefulBuilder(
+    builder: (BuildContext context, void Function(void Function()) setState) {
+      return ListTile(
+        title: Text("软件界面动画"),
+        subtitle: Text(_guiAnimation ? "是" : "否"),
+        onTap: () async {
+          await _chooseGuiAnimation(context);
+          setState(() {});
+        },
+      );
+    },
+  );
+}

lib/screens/AppScreen.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:pikapika/basic/config/GuiAnimation.dart';
 import 'package:pikapika/basic/config/Version.dart';
 import 'package:pikapika/screens/components/Badge.dart';
 
@@ -36,19 +37,33 @@ class _AppScreenState extends State<AppScreen> {
   ];
 
   late int _selectedIndex = 0;
+  PageController _pageController = PageController(initialPage: 0);
 
   void _onItemTapped(int index) {
+    if (currentGuiAnimation()) {
+      _pageController.animateToPage(
+        index,
+        duration: Duration(milliseconds: 200),
+        curve: Curves.ease,
+      );
+    } else {
+      _pageController.jumpToPage(index);
+    }
+  }
+
+  void _onPageChanged(int index) {
     setState(() {
-      _selectedIndex = index;
+      this._selectedIndex = index;
     });
   }
 
   @override
   Widget build(BuildContext context) {
     return Scaffold(
-      body: IndexedStack(
-        index: _selectedIndex,
+      body: PageView(
+        controller: _pageController,
         children: _widgetOptions,
+        onPageChanged: _onPageChanged,
       ),
       bottomNavigationBar: BottomNavigationBar(
         items: <BottomNavigationBarItem>[

lib/screens/CategoriesScreen.dart

@@ -24,7 +24,12 @@ class CategoriesScreen extends StatefulWidget {
   State<StatefulWidget> createState() => _CategoriesScreenState();
 }
 
-class _CategoriesScreenState extends State<CategoriesScreen> {
+class _CategoriesScreenState extends State<CategoriesScreen>
+    with AutomaticKeepAliveClientMixin {
+
+  @override
+  bool get wantKeepAlive => true;
+
   late SearchBar _searchBar = SearchBar(
     hintText: '搜索',
     inBar: false,

lib/screens/InitScreen.dart

@@ -11,6 +11,7 @@ import 'package:pikapika/basic/config/DownloadAndExportPath.dart';
 import 'package:pikapika/basic/config/DownloadThreadCount.dart';
 import 'package:pikapika/basic/config/FullScreenAction.dart';
 import 'package:pikapika/basic/config/FullScreenUI.dart';
+import 'package:pikapika/basic/config/GuiAnimation.dart';
 import 'package:pikapika/basic/config/KeyboardController.dart';
 import 'package:pikapika/basic/config/NoAnimation.dart';
 import 'package:pikapika/basic/config/PagerAction.dart';
@@ -76,6 +77,7 @@ class _InitScreenState extends State<InitScreen> {
     await initNoAnimation();
     await initVersion();
     autoCheckNewVersion();
+    await initGuiAnimation();
     // 登录, 如果token失效重新登录, 网络不好的时候可能需要1分钟
     if (await method.preLogin()) {
       // 如果token或username+password有效则直接进入登录好的界面

lib/screens/SettingsScreen.dart

@@ -13,6 +13,7 @@ import 'package:pikapika/basic/config/DownloadAndExportPath.dart';
 import 'package:pikapika/basic/config/DownloadThreadCount.dart';
 import 'package:pikapika/basic/config/FullScreenAction.dart';
 import 'package:pikapika/basic/config/FullScreenUI.dart';
+import 'package:pikapika/basic/config/GuiAnimation.dart';
 import 'package:pikapika/basic/config/KeyboardController.dart';
 import 'package:pikapika/basic/config/NoAnimation.dart';
 import 'package:pikapika/basic/config/PagerAction.dart';
@@ -43,11 +44,12 @@ class SettingsScreen extends StatelessWidget {
             convertToPNGSetting(),
             readerTypeSetting(),
             readerDirectionSetting(),
+            noAnimationSetting(),
             autoFullScreenSetting(),
             fullScreenActionSetting(),
             volumeControllerSetting(),
             keyboardControllerSetting(),
-            noAnimationSetting(),
+            guiAnimationSetting(),
             Divider(),
             shadowCategoriesModeSetting(),
             shadowCategoriesSetting(),

lib/screens/SpaceScreen.dart

@@ -21,7 +21,10 @@ class SpaceScreen extends StatefulWidget {
   State<StatefulWidget> createState() => _SpaceScreenState();
 }
 
-class _SpaceScreenState extends State<SpaceScreen> {
+class _SpaceScreenState extends State<SpaceScreen>
+    with AutomaticKeepAliveClientMixin {
+  @override
+  bool get wantKeepAlive => true;
 
   @override
   void initState() {