How to scroll ListView horizontally with mouse weel ? Flutter - Web

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05-10-2024

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Scrolling a ListView Horizontally with Mouse Wheel in Flutter Web

Flutter's ListView is designed for vertical scrolling by default. But what if you need to scroll a list of items horizontally using the mouse wheel? This article will guide you through achieving this functionality specifically for Flutter web applications.

The Problem: Horizontal Scrolling in a ListView

Imagine you have a ListView displaying a long list of items, each with a significant width. You want users to be able to scroll through this list horizontally using their mouse wheel, similar to how they might scroll a webpage.

Unfortunately, Flutter's default ListView doesn't inherently support this behavior. Here's a basic example of a ListView that demonstrates the issue:

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Horizontal Scrolling Issue'),
        ),
        body: ListView(
          scrollDirection: Axis.horizontal,
          children: List.generate(10, (index) => Container(
            width: 200,
            height: 100,
            color: Colors.blue[index * 100],
            child: Center(child: Text('Item $index')),
          )),
        ),
      ),
    );
  }
}

This code creates a horizontally scrolling ListView, but it will only scroll vertically with the mouse wheel.

The Solution: Implementing Mouse Wheel Events

The key to implementing horizontal scrolling with the mouse wheel lies in listening for mouse wheel events and manually updating the ListView's scroll position. We can achieve this by wrapping our ListView in a MouseRegion widget.

Here's the updated code:

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Horizontal Scrolling with Mouse Wheel'),
        ),
        body: MouseRegion(
          onHorizontalScroll: (event) {
            // Get the current scroll position
            final ScrollController controller = PrimaryScrollController.of(context);
            // Update the scroll position based on the mouse wheel delta
            controller.jumpTo(controller.offset + event.delta.dx);
          },
          child: ListView(
            scrollDirection: Axis.horizontal,
            children: List.generate(10, (index) => Container(
              width: 200,
              height: 100,
              color: Colors.blue[index * 100],
              child: Center(child: Text('Item $index')),
            )),
          ),
        ),
      ),
    );
  }
}

Explanation:

1. MouseRegion: We wrap our ListView in a MouseRegion widget. This widget allows us to listen for mouse events within its boundaries.

2. onHorizontalScroll: We use the onHorizontalScroll callback to trigger a function whenever the user scrolls horizontally with the mouse wheel.

3. PrimaryScrollController: We obtain the ScrollController associated with our ListView using PrimaryScrollController.of(context). This controller manages the scroll position of the ListView.

4. Updating Scroll Position: The onHorizontalScroll function receives the event object, containing the mouse wheel delta (event.delta.dx) which represents the amount of scrolling. We add this delta to the current scroll offset using controller.jumpTo() to update the ListView's scroll position.

Now, when you run this code, you'll be able to scroll the ListView horizontally using the mouse wheel, just like a regular webpage!

Additional Considerations:

• Scroll Physics: Consider using the BouncingScrollPhysics or ClampingScrollPhysics for a more natural scrolling experience.
• Responsive Design: Ensure your ListView adjusts its size appropriately based on the screen width to avoid content overflow.
• Performance: For very large lists, you might need to explore more efficient scrolling techniques to avoid performance issues.

By combining the power of Flutter widgets and event handling, you can easily achieve horizontal scrolling in your Flutter web application with the mouse wheel. This provides a more intuitive user experience, allowing users to navigate through your lists effortlessly.