Flutter - Float Action Button - Hiding the visibility of items

I used Opacity but it became redundant after using ScaleTransition. With ScaleTransition it is possible to hide and show widgets.

I used 3 animations to be able to generate the cascade effect.

Below is the code and its result:

import 'package:flutter/animation.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(new MaterialApp(home: new HomePage()));
}

class HomePage extends StatefulWidget {
  @override
  HomePageState createState() => new HomePageState();
}

class HomePageState extends State<HomePage> with TickerProviderStateMixin {
  int _angle = 90;
  bool _isRotated = true;

  AnimationController _controller;
  Animation<double> _animation;
  Animation<double> _animation2;
  Animation<double> _animation3;

  @override
  void initState() {
    _controller = new AnimationController(
      vsync: this,
      duration: const Duration(milliseconds: 180),
    );

    _animation = new CurvedAnimation(
      parent: _controller,
      curve: new Interval(0.0, 1.0, curve: Curves.linear),
    );

    _animation2 = new CurvedAnimation(
      parent: _controller,
      curve: new Interval(0.5, 1.0, curve: Curves.linear),
    );

    _animation3 = new CurvedAnimation(
      parent: _controller,
      curve: new Interval(0.8, 1.0, curve: Curves.linear),
    );
    _controller.reverse();
    super.initState();
  }

  void _rotate(){
    setState((){
      if(_isRotated) {
        _angle = 45;
        _isRotated = false;
        _controller.forward();
      } else {
        _angle = 90;
        _isRotated = true;
        _controller.reverse();
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      body: new Stack(
        children: <Widget>[
            new Positioned(
              bottom: 200.0,
              right: 24.0,
              child: new Container(
                child: new Row(
                  children: <Widget>[
                    new ScaleTransition(
                      scale: _animation3,
                      alignment: FractionalOffset.center,
                      child: new Container(
                        margin: new EdgeInsets.only(right: 16.0),
                        child: new Text(
                          'foo1',
                          style: new TextStyle(
                            fontSize: 13.0,
                            fontFamily: 'Roboto',
                            color: new Color(0xFF9E9E9E),
                            fontWeight: FontWeight.bold,
                          ),
                        ), 
                      ),
                    ),

                    new ScaleTransition(
                      scale: _animation3,
                      alignment: FractionalOffset.center,
                      child: new Material(
                        color: new Color(0xFF9E9E9E),
                        type: MaterialType.circle,
                        elevation: 6.0,
                        child: new GestureDetector(
                          child: new Container(
                            width: 40.0,
                            height: 40.0,
                            child: new InkWell(
                              onTap: (){
                                if(_angle == 45.0){
                                  print("foo1");
                                }
                              },
                              child: new Center(
                                child: new Icon(
                                  Icons.add,
                                  color: new Color(0xFFFFFFFF),
                                ),                      
                              ),
                            )
                          ),
                        )
                      ),
                    ),                                     
                  ],
                ),
              )
            ),

          new Positioned(
            bottom: 144.0,
            right: 24.0,
            child: new Container(
              child: new Row(
                children: <Widget>[
                  new ScaleTransition(
                    scale: _animation2,
                    alignment: FractionalOffset.center,
                    child: new Container(
                      margin: new EdgeInsets.only(right: 16.0),
                      child: new Text(
                        'foo2',
                        style: new TextStyle(
                          fontSize: 13.0,
                          fontFamily: 'Roboto',
                          color: new Color(0xFF9E9E9E),
                          fontWeight: FontWeight.bold,
                        ),
                      ), 
                    ),
                  ),

                  new ScaleTransition(
                    scale: _animation2,
                    alignment: FractionalOffset.center,
                    child: new Material(
                      color: new Color(0xFF00BFA5),
                      type: MaterialType.circle,
                      elevation: 6.0,
                      child: new GestureDetector(
                        child: new Container(
                          width: 40.0,
                          height: 40.0,
                          child: new InkWell(
                            onTap: (){
                              if(_angle == 45.0){
                                print("foo2");
                              }
                            },
                            child: new Center(
                              child: new Icon(
                                Icons.add,
                                color: new Color(0xFFFFFFFF),
                              ),                      
                            ),
                          )
                        ),
                      )
                    ),
                  ), 
                ],
              ),
            )
          ),
          new Positioned(
            bottom: 88.0,
            right: 24.0,
            child: new Container(
              child: new Row(
                children: <Widget>[
                  new ScaleTransition(
                    scale: _animation,
                    alignment: FractionalOffset.center,
                    child: new Container(
                      margin: new EdgeInsets.only(right: 16.0),
                      child: new Text(
                        'foo3',
                        style: new TextStyle(
                          fontSize: 13.0,
                          fontFamily: 'Roboto',
                          color: new Color(0xFF9E9E9E),
                          fontWeight: FontWeight.bold,
                        ),
                      ), 
                    ),
                  ),

                  new ScaleTransition(
                    scale: _animation,
                    alignment: FractionalOffset.center,
                    child: new Material(
                      color: new Color(0xFFE57373),
                      type: MaterialType.circle,
                      elevation: 6.0,
                      child: new GestureDetector(
                        child: new Container(
                          width: 40.0,
                          height: 40.0,
                          child: new InkWell(
                            onTap: (){
                              if(_angle == 45.0){
                                print("foo3");
                              }
                            },
                            child: new Center(
                              child: new Icon(
                                Icons.add,
                                color: new Color(0xFFFFFFFF),
                              ),                      
                            ),
                          )
                      ),
                    )
                    ),
                  ), 
                ],
              ),
            )
          ),
          new Positioned(
            bottom: 16.0,
            right: 16.0,
            child: new Material(
              color: new Color(0xFFE57373),
              type: MaterialType.circle,
              elevation: 6.0,
              child: new GestureDetector(
                child: new Container(
                  width: 56.0,
                  height: 56.00,
                  child: new InkWell(
                    onTap: _rotate,
                    child: new Center(
                      child: new RotationTransition(
                        turns: new AlwaysStoppedAnimation(_angle / 360),
                        child: new Icon(
                          Icons.add,
                          color: new Color(0xFFFFFFFF),
                        ),
                      )
                    ),
                  )
                ),
              )
            ),
          ),
        ]
      )
    );
  }
}