flutter how to make Hero like animation between widgets on the same page

Question

I have a button with a text, and when I pressed the button, a text widget with the same text is added to the same page. I'd like to add Hero like animation between them. I guess what I need is SlideTransition, but I don't know how to slide from one widget position to another widget position. Is it possible to do? What widget (or class) should I look into?

Here's the code I want to do (but doesn't work since Hero doesn't work on the same page widgets):

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: MyHomePage(),
    );
  }
}
class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  List<String> text = [];
  String buttonTag = "0";


  @override
  Widget build(BuildContext context) {
    List<Widget> textWidgets = [];
    for (int i = 0; i < text.length; ++i) {
      textWidgets.add(
        Padding(
          padding: const EdgeInsets.all(8.0),
          child: Hero(tag: "${i}", child: Text(text[i])),
        )
      );
    }

    return SafeArea(
      child: Scaffold(
        body: Center(
          child: Column(
            children: <Widget>[
                  RaisedButton(
                    child: Hero(
                        tag: buttonTag,
                        child: Text("abcde${text.length}")),
                    onPressed: () {
                      setState(() {
                        text.add("abcde${text.length}");
                        buttonTag = "${text.length}";
                      });
                    },
                  )
                ] + textWidgets,
          ),
        ),
      ),
    );
  }
}

Answer 1

Not exactly the answer to the question but instead of Hero (if it's possible) you can use AnimatedList to get the same result.

Code snippet

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

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  final GlobalKey<AnimatedListState> _listKey = GlobalKey<AnimatedListState>();
  final List<Text> _textWidgets = [];
  var rng = new Random();
  _addItem() {
    setState(() {
      _listKey.currentState.insertItem(_textWidgets.length,
          duration: const Duration(milliseconds: 500));
      int id = rng.nextInt(100);
      _textWidgets.add(Text('item $id'));
    });
  }

  Widget _buildItem(
      BuildContext context, Text item, Animation<double> animation) {
    final offsetAnimation = Tween<Offset>(
      begin: Offset(1.0, 0.0),
      end: Offset(0.0, 0.0),
    ).animate(animation);
    return SlideTransition(
      position: offsetAnimation,
      child: SizedBox(
        height: 50.0,
        child: Center(
          child: item,
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return SafeArea(
      child: Scaffold(
        body: Column(
          children: <Widget>[
            RaisedButton(
              child: Text("Add Item"),
              onPressed: () {
                setState(() {
                  _addItem();
                });
              },
            ),
            Expanded(
              child: AnimatedList(
                key: _listKey,
                initialItemCount: _textWidgets.length,
                itemBuilder: (context, index, animation) {
                  return _buildItem(context, _textWidgets[index], animation);
                },
              ),
            ),
          ],
        ),
      ),
    );
  }
}

Answer 2

I think it's possible by this llibrary which named: LocalHero

Answer 3

Implement your self

The AnimationController , Tween , AnimatedBuilder are key components.

This is a sample and code about this.

Don't use AnimatedController.animate in AnimatedBuilder builder.

evaluate is enough. Because the builder function is called every ticker frame.

Use AnimationController.animate as class member field.

class _AuthorizedState extends State<_Authorized> with SingleTickerProviderStateMixin {
  late final _menuAC = AnimationController(vsync: this, duration: 200.ms);
  late final isFilterOpen = ValueNotifier(false)..addListener(_handleFilterOpenChanged);

  late final filterColor =
      ColorTween(begin: context.color.primaryContainer, end: context.color.secondaryContainer)
          .animate(_menuAC);
  late final filterBorderRadius = Tween<double>(begin: 12, end: 0).animate(_menuAC);

  void _handleFilterOpenChanged() {
    print(isFilterOpen.value);
    if (isFilterOpen.value) {
      _menuAC.forward();
    } else {
      _menuAC.reverse();
    }
  }

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

  @override
  Widget build(BuildContext context) {
    return AppScaffold(
      child: LayoutBuilder(
        builder: (context, cons) => Stack(
          children: [
                        AnimatedBuilder(
              animation: _menuAC,
              builder: (context, child) {
                return Positioned(
                  bottom: Tween(begin: 16.0, end: 0.0).evaluate(_menuAC),
                  right: Tween(begin: 16.0, end: 0.0).evaluate(_menuAC),
                  child: ClipRRect(
                    borderRadius: BorderRadius.only(
                      topLeft: const Radius.circular(12.0),
                      topRight: const Radius.circular(12.0),
                      bottomLeft:
                          Radius.circular(Tween<double>(begin: 12, end: 0).evaluate(_menuAC)),
                      bottomRight:
                          Radius.circular(Tween<double>(begin: 12, end: 0).evaluate(_menuAC)),
                    ),
                    child: Container(
                      width: Tween(begin: 56.0, end: cons.maxWidth).evaluate(_menuAC),
                      height: Tween(begin: 56.0, end: min(cons.maxHeight * 0.7, 500.0))
                          .evaluate(_menuAC),
                      decoration: BoxDecoration(
                        color: filterColor.value,
                      ),
                      child: child,
                    ),
                  ),
                );
              },
              child: Material(
                elevation: 24,
                color: Colors.transparent,
                child: InkWell(
                  onTap: () {
                    isFilterOpen.value = !isFilterOpen.value;
                  },
                  child: const Center(child: Icon(MdiIcons.filter)),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}