flutter - currentTabのTabItemのアイコンを変更する方法

Question

アクティブおよび非アクティブでの色の変更で完全に機能する BottomNavigationBar がありますが、色を変更したくはありませんが、アクティブおよび非アクティブのアイコンを SVG イメージで変更します。以下は私のコードです：

class AppNavigation extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => AppState();
}

const assetHome = 'assets/home_off.svg';
const assetRedemptions = 'assets/redeemed_off.svg';
const assetProfile = 'assets/profile_off.svg';


const assetHome1 = 'assets/home_on.svg';
const assetRedemptions1 = 'assets/redeemed_on.svg';
const assetProfile1 = 'assets/profile_on.svg';


class AppState extends State<AppNavigation> {
 
  static int currentTab = 0;

 // list tabs here
  final List<TabItem> tabs = [
    TabItem(
      tabName: "Home",
      icon: Icons.home,
      page: MyDealApp(),
    ),
    TabItem(
      tabName: "Announcement",
      icon: Icons.announcement,
      page: MyRedemptionApp(),
    ),
    TabItem(
      tabName: "Notification",
      icon: Icons.notifications,
      page: MyProfileApp(),
    ),
  ];

  AppState() {
    tabs.asMap().forEach((index, details) {
      details.setIndex(index);
    });
  }

  void _selectTab(int index) {
    if (index == currentTab) {
      tabs[index].key.currentState.popUntil((route) => route.isFirst);
   
    } else {
      setState(() => currentTab = index);
      debugPrint("currentTabber:$currentTab");
    }
  }

  @override
  Widget build(BuildContext context) {
    // WillPopScope handle android back btn
    return WillPopScope(
      onWillPop: () async {
        final isFirstRouteInCurrentTab =
        !await tabs[currentTab].key.currentState.maybePop();
        if (isFirstRouteInCurrentTab) {
          // if not on the 'main' tab
          if (currentTab != 0) {
            // select 'main' tab
            _selectTab(0);
            // back button handled by app
            return false;
          }
        }
        return isFirstRouteInCurrentTab;
      },
      child: Scaffold(
        // indexed stack shows only one child
        body: IndexedStack(
          index: currentTab,
          children: tabs.map((e) => e.page).toList(),
        ),
        // Bottom navigation
        bottomNavigationBar: BottomNavigation(
          onSelectTab: _selectTab,
          tabs: tabs,
        ),
      ),
    );
  }
}

class TabItem {
  // you can customize what kind of information is needed
  // for each tab
  final String tabName;
  final IconData icon;
  final GlobalKey<NavigatorState> key = GlobalKey<NavigatorState>();
  int _index = 0;
  Widget _page;

  TabItem({
    @required this.tabName,
    @required this.icon,
    @required Widget page,
  }) {
    _page = page;
  }

  void setIndex(int i) {
    _index = i;
  }

  int getIndex() => _index;

  Widget get page {
    return Visibility(
      // only paint this page when currentTab is active
      visible: _index == AppState.currentTab,
      // important to preserve state while switching between tabs
      maintainState: true,
      child: Navigator(
        // key tracks state changes
        key: key,
        onGenerateRoute: (routeSettings) {
          return MaterialPageRoute(
            builder: (_) => _page,
          );
        },
      ),
    );
  }
}

class BottomNavigation extends StatelessWidget {
  BottomNavigation({
    this.onSelectTab,
    this.tabs,
  });

  final ValueChanged<int> onSelectTab;
  final List<TabItem> tabs;

  @override
  Widget build(BuildContext context) {
    return BottomNavigationBar(
      type: BottomNavigationBarType.fixed,
      items: tabs
          .map(
            (e) => _buildItem(
          index: e.getIndex(),
          icon: e.icon,
          tabName: e.tabName,
        ),
      )
          .toList(),
      onTap: (index) => onSelectTab(
        index,
      ),
    );
  }

  BottomNavigationBarItem _buildItem(
      {int index, IconData icon, String tabName}) {
    return BottomNavigationBarItem(
      icon: Icon(
        icon,
        color: _tabColor(index: index),
      ),
      title: Text(
        tabName,
        style: TextStyle(
          color: _tabColor(index: index),
          fontSize: 12,
        ),
      ),
    );
  }

  Color _tabColor({int index}) {
    return AppState.currentTab == index ? colorGreen : Colors.grey;
  }

 }

ご覧 のとおり_tabColor、アクティブと非アクティブで色を青から灰色に切り替えますが、上記の宣言された SVG イメージを使用してアイコンを切り替えたいと思います。アクティブassetHomeなときと非アクティブなとき、アクティブなときと非アクティブなとき、最後にアクティブなときと非アクティブなとき。MyDealApp()assetHome1MyDealApp()assetRedemptionsMyRedemptionApp()assetRedemptions1MyRedemptionApp()assetProfileMyProfileApp()assetProfile1MyProfileApp()