scroll_controller_override 0.0.1
scroll_controller_override: ^0.0.1 copied to clipboard
Helper class for overriding scroll controller methods.
import 'dart:math';
import 'package:flutter/material.dart';
import 'package:scroll_controller_override/scroll_controller_override.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
useMaterial3: true,
),
home: const MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({super.key, required this.title});
final String title;
@override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
late ScrollControllerOverride scrollController;
double top = 0;
@override
void initState() {
super.initState();
scrollController = ScrollControllerOverride(overrideMethod: ScrollOverrideMethod(
applyUserOffset: (double delta, void Function(double delta) superMethod) {
bool listShouldScroll = scrollController.position.pixels > 0.0;
if (!listShouldScroll) {
double newVal = top + delta;
newVal = max(0, newVal);
if (newVal != top) {
setState(() {
top = newVal;
});
} else {
superMethod(delta);
}
} else {
superMethod(delta);
}
},
));
}
void _incrementCounter() {
setState(() {
_counter++;
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
backgroundColor: Theme.of(context).colorScheme.inversePrimary,
title: Text(widget.title),
),
body: Stack(
children: [
Transform.translate(
offset: Offset(0, top),
child: ScrollPointerListener(
onPointerDown: (i) {
print("onPointerDown");
},
onPointerUp: (i) {
print("onPointerUp");
},
onPointerCancel: (i) {
print("onPointerCancel");
},
child: CustomScrollView(
physics: const ClampingScrollPhysics(),
controller: scrollController,
slivers: [
SliverList(
delegate: SliverChildListDelegate(
List.generate(
20,
(e) {
return Container(height: 100, width: double.infinity, color: Colors.amber, child: Placeholder());
},
),
),
),
],
),
),
)
],
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: const Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}