Flutter scroll to specific item in list

Question

I have a ListView in Flutter that I allow users to dynamically add items to. After adding an item I would like for the list to scroll to the item that was added. I've attached a ScrollController to the ListView so I could use animateTo to scroll, but I'm unsure of how to determine the offset to scroll down to. I had something like this:

_scrollController.animateTo(
    addedIndex.toDouble() * 100,
    curve: Curves.easeOut,
    duration: const Duration(milliseconds: 300),
);

where addedIndex is the order that the item was added to the list. That doesn't quite work though, and seems like it would only work if I could figure out the height of each item in the list, which I'm not sure how to do. Is there a better way to figure out exactly where to scroll to?

Amberjack

Answer 1

First, create a new globalKey.

final GlobalKey globalKey = GlobalKey();

Second, add globalKey to the widget you want to move to.

Then, get the widget location based on globalKey.

RenderBox box = globalKey.currentContext.findRenderObject();
Offset offset = box.localToGlobal(Offset.zero);

The widget position obtained is relative to the current page display status , widget height includes status bar and AppBar height.

status bar height

import 'dart:ui’; 
MediaQueryData.fromWindow(window).padding.top

AppBar height 56.0

scrollView's offset need to add

double animationHeight = _controller.offset + offset.dy - MediaQueryData.fromWindow(window).padding.top - 56.0;
_controller.animateTo(animationHeight, duration: Duration(milliseconds: 500), curve: Curves.decelerate);

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hope it will help you.

Bronchiectasis

This helped me a lot! Thank you, buddy! – Redblooded

Answer 2

Would using a StreamBuilder that adds items to an AnimatedList work. Every time the stream emits a new item, it is added to the AnimatedList which shows it as the latest entry in the list similar to how chat messages work. The latest message is appended to the AnimatedList.

Flashover