How do I add overflow to Lists in Flutter?

Question

I want to add an overscrolls at the end and at the top of the list, only if someone overscrolls.

So... I had a few ideas, I tried to start by using a GestureDetector, and it seems to not work if the list is bigger than the screen, then I went adding a ListView Scroller controller, but it only works if the List is bigger than the screen.

I went ahead an tried to add it through Notification, but it seems too slow.

Any ideas?

class _PullableListState extends State<PullableList> {
  double overScrollOnEnd = 0;

  @override
  Widget build(BuildContext context) {
    return NotificationListener<ScrollNotification>(
      onNotification: (notification) {
        // print(notification.metrics.pixels);
        if (notification is OverscrollNotification) {
          setState(() {
            overScrollOnEnd += notification.dragDetails.delta.dy;
          });
          print(overScrollOnEnd);
        }
        if (notification is ScrollUpdateNotification) {
          setState(() {
            overScrollOnEnd = 0;
          });
        }
        return true;
      },
      child: Container(
        margin: EdgeInsets.only(top: max(overScrollOnEnd, 0)),
        child: ListView.builder(
          itemBuilder: widget.itemBuilder,
          itemCount: widget.itemCount,
        ),
      ),
    );
  }
}

uanirudhx · Accepted Answer · 2020-09-19 02:00:08Z

2

You want AlwaysScrollableScrollPhysics combined with BouncingScrollPhysics.

class _PullableListState extends State<PullableList> {
  double overScrollOnEnd = 0;

  @override
  Widget build(BuildContext context) {
    return Container(
      margin: EdgeInsets.only(top: max(overScrollOnEnd, 0)),
      child: ListView.builder(
        physics: BouncingScrollPhysics(parent: AlwaysScrollableScrollPhysics()),
        itemBuilder: widget.itemBuilder,
        itemCount: widget.itemCount,
      ),
    );
  }
}

answered Sep 19, 2020 at 2:00

uanirudhx

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3 Comments

Miguel Angel Guerrero Salinas Over a year ago

This seems like the solution for the problem.

Miguel Angel Guerrero Salinas Over a year ago

If I wanted to add an action, lets say if I were to overflow by an X amount, how would you add it? ( You already answered my question, so I thank you, I'm just waiting for the 10 minutes to approve your answer ).

uanirudhx Over a year ago

For that you'd still have to use ScrollNotifications. This is just the scroll physics, and it doesn't emit any events on its own.

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