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All Languages >> Whatever >> No TabController for TabBar. When creating a TabBar, you must either provide an explicit TabController using the "controller" property

“No TabController for TabBar. When creating a TabBar, you must either provide an explicit TabController using the "controller" property” Code Answer

No TabController for TabBar. When creating a TabBar, you must either provide an explicit TabController using the "controller" property

whatever by Sore Sardine

on May 16 2022 Comment

// 1.0 set : with TickerProviderStateMixin {}
// 2.0 declare : TabController _tabController = TabController(
// 3.0 we must add : controller: .., property to TabBar() & TabBarView()
// 4.0 and Set width, height for Parent widget of TabBarView() : set Area for content


import 'package:flutter/material.dart';

class TabBarWidget extends StatefulWidget {
  const TabBarWidget({Key? key}) : super(key: key);

  @override
  _TabBarWidgetState createState() => _TabBarWidgetState();
}

class _TabBarWidgetState extends State<TabBarWidget>
    with TickerProviderStateMixin {  // * 1.0
  
  @override
  Widget build(BuildContext context) {
    TabController _tabController =
        TabController(vsync: this, length: 3); // * 2.0

    return Scaffold(
      body: Column(
        children: [
          SizedBox(
            child: TabBar(
              controller: _tabController, // * 3.1
              labelColor: Colors.black87,
              labelStyle: const TextStyle(fontSize: 18),
              unselectedLabelColor: Colors.grey,
              isScrollable: true,  // can scroll horizontal axis
              indicator: const CircleTabIndicator(
              	color: Colors.black87,
                radius: 4,
              ),
              tabs: const [
                Tab(
                  child: Text('Flutter'),
                ),
                Tab(
                  child: Text('React'),
                ),
                Tab(
                  child: Text('Swift'),
                )
              ],
            ),
          ),
          SizedBox(
            width: double.maxFinite, //  * 4.1
            height: 300, //  * 4.2
            child: TabBarView(
              controller: _tabController, // * 3.2
              children: const [
                Text('Flutter'),
                Text('React'),
                Text('Swift'),
              ],
            ),
          ),
        ],
      ),
    );
  }
}

// BoxPainter
class CirclePainter extends BoxPainter {
  final double radius;
  final Color color;
  CirclePainter({
    required this.radius,
    required this.color,
  });

  @override
  void paint(Canvas canvas, Offset offset, ImageConfiguration configuration) {
    late Paint _paint;

    _paint = Paint()..color = color;
    _paint = _paint..isAntiAlias = true;

    final Offset circleOffset = offset +
        Offset(
            configuration.size!.width / 2, configuration.size!.height - radius);

    canvas.drawCircle(circleOffset, radius, _paint);
  }
}


// Custom Indicator
class CircleTabIndicator extends Decoration {
  final Color color;
  final double radius;

  const CircleTabIndicator({
    required this.color,
    required this.radius,
  });

  @override
  BoxPainter createBoxPainter([VoidCallback? onChanged]) {
    // throw UnimplementedError();
    return CirclePainter(radius: radius, color: color);
  }
}

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