Hero animation and scroll to position between two list in Flutter

Question

I am displaying files as thumbnails such as the Instagram user's profile.

When i click on an item (thumbnail) i have to perform a Hero animation that will reveal the full screen page.

I also want to open the full screen page with the whole list which is directly starting at the given index of the selected post, exactly like in Instagram.

Here is a short GIF that shows better what i mean :

I have tried the scroll_to_index package but this does not meet my needs (animation is broken and too slow).

How can i achieve this please ?

Solution

this is what i've done, try:

import 'package:flutter/material.dart';

import 'package:scrollable_positioned_list/scrollable_positioned_list.dart';

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

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

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

class _HomePageState extends State<HomePage> {
  @override
  void initState() {
    super.initState();
  }

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: GridView.count(
        crossAxisCount: 3,
        children: List.generate(99, (index) {
          return Container(
            width: double.infinity,
            height: double.infinity,
            child: GestureDetector(
              onTap: () {
                Navigator.push(
                  context,
                  MaterialPageRoute(
                      builder: (context) => ListPage(index: index)),
                );
              },
              child: Hero(
                tag: 'photo$index',
                child: Image.network(
                  'https://images.unsplash.com/photo-1628701621033-50564c683bb0?ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&ixlib=rb-1.2.1&auto=format&fit=crop&w=800&q=80',
                  fit: BoxFit.cover,
                ),
              ),
            ),
          );
        }),
      ),
    );
  }
}

class ListPage extends StatefulWidget {
  final int index;

  ListPage({Key key, @required this.index}) : super(key: key);

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

class _ListPageState extends State<ListPage> {
  final ItemScrollController itemScrollController = ItemScrollController();
  final ItemPositionsListener itemPositionsListener =
      ItemPositionsListener.create();

  @override
  void initState() {
    super.initState();
  }

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

  @override
  Widget build(BuildContext context) {
    return ScrollablePositionedList.builder(
      initialScrollIndex: widget.index,
      itemCount: 99,
      itemBuilder: (context, index) {
        return Column(
          children: [
            AspectRatio(
              aspectRatio: 1,
              child: Hero(
                tag: 'photo$index',
                child: Image.network(
                  'https://images.unsplash.com/photo-1628701621033-50564c683bb0?ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&ixlib=rb-1.2.1&auto=format&fit=crop&w=800&q=80',
                  fit: BoxFit.cover,
                ),
              ),
            ),
            Container(
              height: 50,
              width: MediaQuery.of(context).size.width,
              child: Text('$index'),
            ),
          ],
        );
      },
      itemScrollController: itemScrollController,
      itemPositionsListener: itemPositionsListener,
    );
  }
}

Comments

[Tom3652]

Thanks for your answer, but the package you are using is not null safety. I have not specified it in my question my bad. I would like the logic to work with any scrollable list actually but if you have a working null safety example i will try it right away !

[Jim]

it did have null safety version, pub.dev/packages/scrollable_positioned_list/versions/…

[Tom3652]

It's working very fine thank you. I had a conflict with SmartRefresher package in case others faces weird scrolling issues with ScrollablePositionedList (it was scrolling to bottom despite the initial index, that's why i took me so long to validate.

[Jim]

glad that helps, TGIF!