spinner.dart

import 'dart:math' as math;
import 'package:flutter/material.dart';

class Spinner extends StatefulWidget {
  final Widget child;
  final bool reverse;

  const Spinner({Key key, @required this.child, this.reverse = false})
      : super(key: key);

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

class _SpinnerState extends State<Spinner> with SingleTickerProviderStateMixin {
  AnimationController _controller;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      duration: const Duration(seconds: 1),
      vsync: this,
    )..repeat();
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      animation: _controller,
      child: widget.child,
      builder: (BuildContext context, Widget child) {
        return Transform.rotate(
          angle: _controller.value * (widget.reverse ? -2 : 2) * math.pi,
          child: child,
        );
      },
    );
  }
}