Flutter PageView: Proper scrolling with Scrollwheel, Touchpad and Touchscreen

main.dart

import 'package:flutter/material.dart';
import 'package:flutter/gestures.dart';
import 'dart:async';
import 'dart:io' show Platform;
import 'package:flutter/foundation.dart' show kIsWeb;
import 'package:universal_html/html.dart' as html;

bool isDesktop() {
  final userAgent = html.window.navigator.userAgent.toString().toLowerCase();
  if (kIsWeb) {
    return !(userAgent.contains("iphone") ||
        userAgent.contains("android") ||
        userAgent.contains("ipad"));
  } else {
    return !(Platform.isAndroid || Platform.isIOS);
  }
}

class Homepage extends StatefulWidget {
  @override
  _HomepageState createState() => _HomepageState();
}

class _HomepageState extends State<Homepage> {
  final PageController pageController = PageController();
  bool pageIsScrolling = false;

  // Debounce duration in milliseconds
  final int debounceDuration = 20;
  Timer? _debounce;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: isDesktop() ? _buildGestureDetector() : _buildPageView(),
      ),
    );
  }

  Widget _buildGestureDetector() {
    return GestureDetector(
      onPanUpdate: (details) {
        _onScroll(details.delta.dy * -1);
      },
      child: Listener(
        onPointerSignal: (pointerSignal) {
          if (pointerSignal is PointerScrollEvent) {
            _onScroll(pointerSignal.scrollDelta.dy);
          }
        },
        child: _buildPageView(),
      ),
    );
  }

  Widget _buildPageView() {
    return PageView(
      scrollDirection: Axis.vertical,
      controller: pageController,
      physics: isDesktop()
          ? const NeverScrollableScrollPhysics()
          : const AlwaysScrollableScrollPhysics(),
      pageSnapping: true,
      children: [
        Container(color: Colors.red),
        Container(color: Colors.blue),
        Container(color: Colors.orange),
      ],
    );
  }

  void _onScroll(double offset) {
    if (!pageIsScrolling) {
      pageIsScrolling = true;

      _debounce = Timer(Duration(milliseconds: debounceDuration), () {
        if (offset > 0) {
          pageController
              .nextPage(
                duration: const Duration(milliseconds: 300),
                curve: Curves.easeInOut,
              )
              .then((value) => pageIsScrolling = false);
        } else {
          pageController
              .previousPage(
                duration: const Duration(milliseconds: 300),
                curve: Curves.easeInOut,
              )
              .then((value) => pageIsScrolling = false);
        }
      });
    }
  }

  @override
  void dispose() {
    _debounce?.cancel();
    super.dispose();
  }
}

void main() {
  runApp(MaterialApp(
    home: Homepage(),
  ));
}