nested_scroll_view_plus

An enhanced NestedScrollView offering overscroll support for both the nested and parent scroll views, ensuring a seamless scrolling experience.

🔥 Preview

Try it online: https://flutter-nested-scroll-view-plus.vercel.app

💡 Usage

Installation:

flutter pub add nested_scroll_view_plus

Example usage:

import 'package:nested_scroll_view_plus/nested_scroll_view_plus.dart';

// Step 1: Replace `NestedScrollView` with `NestedScrollViewPlus`
NestedScrollViewPlus(
  headerSliverBuilder: (context, innerScrolled) => <Widget>[
    // ... insert your header sliver widgets here
  ],
  body: CustomScrollView(
    // Step 2: [🚨IMPORTANT] Set the physics of `CustomScrollView` to `AlwaysScrollableScrollPhysics`
    physics: const BouncingScrollPhysics(
      parent: AlwaysScrollableScrollPhysics(),
    ),
    slivers: <Widget>[
      // ... insert your body sliver widgets here
    ],
  ),
);

For additional examples, please visit the scroll_master repository. It includes features such as pull-to-refresh for NestedScrollView, combined scrolling for scrollview and tabview, and more.

🚀 Upgrade and Migration Guide

With the release of version 2.0.0, there are a few important changes that require action when upgrading from an earlier version.

For Deprecated Widgets:

If you are using OverlapAbsorberPlus or OverlapInjectorPlus in your code, follow these steps:

• Locate any header slivers wrapped with OverlapAbsorberPlus and remove the OverlapAbsorberPlus wrapper.
• Remove any OverlapInjectorPlus widget that was placed atop your scroll views.

For OverscrollBehavior:

Search your codebase for any instance of OverscrollType and replace it with OverscrollBehavior. This will ensure compatibility with the new naming convention.

By following these steps, you should be able to smoothly transition to version 2.0.0 without any significant issues. As always, it is recommended to test your application thoroughly after performing an upgrade to ensure that all features work as intended.

⚙️ Accessing the Inner or Outer Scroll Controller

To access the inner or outer scroll controller of a NestedScrollViewPlus, you can use a GlobalKey<NestedScrollViewStatePlus> to get its state.

class _ExampleState extends State<Example> {
  // 1. Create a GlobalKey
  final GlobalKey<NestedScrollViewStatePlus> myKey = GlobalKey();

  @override
  Widget build(BuildContext context) {
    return NestedScrollViewPlus(
      // 2. Set the key to NestedScrollViewStatePlus
      key: myKey,
      // ...,
    );
  }

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
      // 3. Access the inner or outer scroll controller using GlobalKey<NestedScrollViewStatePlus>
      myKey.currentState!.innerController.addListener(_handleInnerScroll);
      myKey.currentState!.outerController.addListener(_handleOuterScroll);
    });
  }

  void _handleInnerScroll() {
    final innerController = myKey.currentState!.innerController;
    if (innerController.positions.length == 1) {
      print('Scrolling inner nested scrollview: ${innerController.offset}');
    }
  }

  void _handleOuterScroll() {
    final outerController = myKey.currentState!.outerController;
    if (outerController.positions.length == 1) {
      print('Scrolling outer nested scrollview: ${outerController.offset}');
    }
  }
}

🚩 Preserve Scroll Positions of Inner CustomScrollViews

To preserve the scroll positions of inner CustomScrollViews, you can add a PageStorageKey to the CustomScrollView widget. Here's an example:

CustomScrollView(
  key: PageStorageKey<String>('unique-key'),
  slivers: <Widget>[
    // ...,
  ],
),

By assigning a unique key to the CustomScrollView, Flutter's PageStorage mechanism will store and restore the scroll position of the inner CustomScrollViews, allowing you to maintain the scroll positions even when the widget tree is rebuilt.

⭕️ For Older Flutter Versions

If you are using an older version of Flutter, please follow these steps to install the appropriate branch from the old git repository.

dependencies:
  custom_nested_scroll_view:
    git:
      url: https://github.com/idootop/custom_nested_scroll_view.git
      # Choose the branch based on your local Flutter version
      ref: flutter-3.7

The different branches support the following Flutter versions:

Git branch	Supported flutter versions
flutter-3.7	>=3.7.0-13.0.pre
flutter-3.4	>=3.4.0-27.0.pre <3.7.0-13.0.pre
flutter-3.4-pre	>=3.4.0-17.0.pre <3.4.0-27.0.pre
flutter-3.0	>=2.12.0-4.0.pre <3.4.0-17.0.pre
flutter-2.x	<2.12.0-4.0.pre

For more details, please visit the old documentation for CustomNestedScrollView.

❤️ Acknowledgements

• Flutter - 循序渐进 Sliver
• 大道至简：Flutter 嵌套滑动冲突解决之路
• 深入进阶-如何解决 Flutter 上的滑动冲突？
• 用 Flutter 实现 58App 的首页
• 不一样角度带你了解 Flutter 中的滑动列表实现
• Flutter 滑动体系