Flutter - Change the animation of TabBarView

molundb picture molundb · Oct 19, 2018 · Viewed 9.5k times · Source

I implemented a basic TabBar and TabBarView with a DefaultTabController, see code below.

class MyApp2 extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return DefaultTabController(
      length: BOTTOM_TABS,
      child: Scaffold(
        appBar: AppBar(title: const Text('Bottom App Bar')),
        body: _tabBarView(),
        bottomNavigationBar: _bottomTabBar(),
      ),
    );
  }

  _tabBarView() {
    return TabBarView(
      physics: NeverScrollableScrollPhysics(),
      children: [
        Container(
          color: Colors.blue,
        ),
        Container(
          color: Colors.orange,
        ),
        Container(
          color: Colors.lightGreen,
        ),
        Container(
          color: Colors.red,
        ),
      ],
    );
  }

  _bottomTabBar() {
    return TabBar(
      tabs: [
        Tab(
          icon: new Icon(Icons.home),
        ),
        Tab(
          icon: new Icon(Icons.public),
        ),
        Tab(
          icon: new Icon(Icons.group),
        ),
        Tab(
          icon: new Icon(Icons.person),
        )
      ],
    );
  }
}

Works great! Now what I want to do is change the animation between the two tabs from the default animation. But I can't find an easy way to do that.

After a bit of research it seems like I need to use a custom TabController and somehow use its animateTo method. To me that seems like a pretty big change just to change the animation. What I wonder is if that is the correct way or if I am missing some easier way to just change the default animation between the tabviews?

If someone could give me some good resources to point me in the right direction I'd greatly appreciate it.

Answer

Kherel picture Kherel · Aug 19, 2019

This is not hard, just use TabController (to do so you need to use SingleTickerProviderStateMixin ) and AnimatedBuilder.

enter image description here

class MyApp2 extends StatefulWidget {
  @override
  _MyApp2State createState() => _MyApp2State();
}

class _MyApp2State extends State<MyApp2> with SingleTickerProviderStateMixin {
  TabController _tabController;

  @override
  void initState() {
    _tabController = TabController(length: 4, vsync: this);
    super.initState();
  }

  _tabBarView() {
    return AnimatedBuilder(
      animation: _tabController.animation,
      builder: (BuildContext context, snapshot) {
        return Transform.rotate(
          angle: _tabController.animation.value * pi,
          child: [
            Container(
              color: Colors.blue,
            ),
            Container(
              color: Colors.orange,
            ),
            Container(
              color: Colors.lightGreen,
            ),
            Container(
              color: Colors.red,
            ),
          ][_tabController.animation.value.round()],
        );
      },
    );
  }

  _bottomTabBar() {
    return TabBar(
      controller: _tabController,
      labelColor: Colors.black,
      tabs: [
        Tab(
          icon: new Icon(Icons.home),
        ),
        Tab(
          icon: new Icon(Icons.public),
        ),
        Tab(
          icon: new Icon(Icons.group),
        ),
        Tab(
          icon: new Icon(Icons.person),
        )
      ],
    );
  }

  @override
  Widget build(BuildContext context) {
    return DefaultTabController(
      length: 4,
      child: Scaffold(
        appBar: AppBar(title: const Text('Bottom App Bar')),
        body: _tabBarView(),
        bottomNavigationBar: _bottomTabBar(),
      ),
    );
  }
}