how to Prevent Listview from ever scrolling between certain bounds? - flutter

Question

I've a initialScrollOffset in my ScrollController set to 100. This allows the top of my ListView in my Scaffold body to appear under my appBar. (Desired behaviour, my appbar is transparent). This works fine when the page first loads but I'd like my ScrollController to prevent my listView from ever scrolling between 0 and 100 and always have an initialScrollOffset of 100. ScrollController has a boolean property keepScrollOffset` but that doesn't prevent the scroll going from 0-100. Here is my code so far:
import 'package:flutter/material.dart';
class HomePage extends StatefulWidget {
#override
_HomePageState createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
ScrollController _scrollController;
#override
Widget build(BuildContext context) {
return Scaffold(
extendBodyBehindAppBar: true,
appBar: AppBar(
backgroundColor: Colors.transparent,
elevation: 0.0,
),
body: Container(
color: Colors.blue.withOpacity(0.25),
child: ListView.builder(
itemCount: 30,
itemBuilder: (context, index) {
return Container(
color: Colors.primaries[index % Colors.primaries.length].withOpacity(0.5),
child: ListTile(
title: Text('Item $index'),
),
);
},
controller: _scrollController,
),
),
);
}
#override
void initState() {
_scrollController = ScrollController(initialScrollOffset: 100, keepScrollOffset: true)
..addListener(() {
print("offset = ${_scrollController.offset}");
});
super.initState();
}
}
void main() {
runApp(MaterialApp(home: HomePage()));
}

Answer 1

If you want to add padding to the inner content that scrolls up and down with the items, you can just add padding to the ListView.
padding: EdgeInsets.only(top: 100)
Not necessary to use ScrollController.