How to create infinity PageView in Flutter

Question

How to create an PageView which are supported circle scroll in Flutter? That's mean when I stand on 0 page, I could scroll to left to the last page.

Updated: I answered this question and update a gist source also.

Answer 1

What I did with mine was I set my page controller's initialPage to 10000 * pageCount, and in my page view itself, I have itemBuilder: (context, index) => pages[index % pageCount], and itemCount: null. It's not really infinite, but most users will not scroll 10000 pages back, so it works for my use case. As far as I know, there isn't an elegant way to make it truly infinite. You could probably set up a listener so that whenever the controller.page is about to become 0, you set it back to 10000 * pageCount or something similar.

Answer 2

I found a solution here. I create a CustomScrollView with 2 slivers. One for go forward, one for go back. However, I have to calculate if my list short.

typedef Widget Builder(BuildContext buildContext, int index);

class InfiniteScrollView extends StatefulWidget {
  final Key center = UniqueKey();
  final Builder builder;
  final int childCount;

  InfiniteScrollView(
      {Key key, @required this.builder, @required this.childCount})
      : super(key: key);

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

class _InfiniteScrollViewState extends State<InfiniteScrollView> {
  @override
  Widget build(BuildContext context) {
    return Container(
      child: CustomScrollView(
        center: widget.center,
        scrollDirection: Axis.horizontal,
        slivers: <Widget>[
          SliverList(
            delegate: SliverChildBuilderDelegate(
              (BuildContext context, int index) => widget.builder(
                  context, widget.childCount - index % widget.childCount - 1),
            ),
          ),
          SliverList(
            delegate: SliverChildBuilderDelegate(widget.builder),
            key: widget.center,
          )
        ],
      ),
    );
  }
}

Updated: I write a new widget which support infinity TabBar.

https://gist.github.com/MrNinja/6f6a5fc73803bdfaf2a493a35c258fee