collapsible_tab_bar

A Material tab bar that shrinks smoothly on scroll and snaps back on tap, with pluggable tab styles. Drive the collapse from any scroll position (a ScrollController/ScrollNotification, a SliverPersistentHeader, etc.) by feeding a 0.0–1.0 progress value into CollapseScope.

Features

• ButtonsTabBar — a PreferredSizeWidget tab bar with per-tab filled or transparent card backgrounds, a selection underline, and a height that interpolates down to 31px as collapse progress goes from 0 to 1.
• Four tab content styles:
  • ButtonsTab — image icon + label (shrinks/fades icon as it collapses).
  • TextButtonsTab — text only, with optional badge overlay.
  • IconButtonsTab — IconData icon only.
  • IconLabelTab — IconData icon + label (same collapse behavior as ButtonsTab, no image assets required).
• CollapseScope — an InheritedWidget that publishes collapseProgress (0.0–1.0) and isCollapsed to the tab bar and its tabs.

Usage

Drive CollapseScope's progress from your own scroll listener, then pass it down to a ButtonsTabBar:

import 'package:collapsible_tab_bar/collapsible_tab_bar.dart';

class MyScreen extends StatefulWidget {
  const MyScreen({super.key});

  @override
  State<MyScreen> createState() => _MyScreenState();
}

class _MyScreenState extends State<MyScreen> with TickerProviderStateMixin {
  late final TabController _tabController =
      TabController(length: 2, vsync: this);
  late final AnimationController _collapseController = AnimationController(
    vsync: this,
    duration: const Duration(milliseconds: 200),
  );

  bool _onScroll(ScrollNotification notification) {
    if (notification.metrics.axis != Axis.vertical) return false;
    if (notification is ScrollUpdateNotification) {
      final double progress =
          (notification.metrics.pixels / 60.0).clamp(0.0, 1.0);
      _collapseController.value = progress;
    }
    return false;
  }

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      animation: _collapseController,
      builder: (context, _) {
        return CollapseScope(
          isCollapsed: _collapseController.value >= 1.0,
          collapseProgress: _collapseController.value,
          child: Scaffold(
            appBar: ButtonsTabBar(
              controller: _tabController,
              tabs: const [
                IconLabelTab(icon: Icons.home_rounded, label: 'Home', index: 0),
                IconLabelTab(icon: Icons.person_rounded, label: 'Profile', index: 1),
              ],
            ),
            body: NotificationListener<ScrollNotification>(
              onNotification: _onScroll,
              child: TabBarView(
                controller: _tabController,
                children: const [Center(child: Text('Home')), Center(child: Text('Profile'))],
              ),
            ),
          ),
        );
      },
    );
  }
}

See example/ for a complete, runnable demo (4-tab card-style bar matching a real app's collapsing header, with corner radius animating from fully rounded to top-only rounded as it collapses).

Notes

• ButtonsTab (the image-asset variant) reads SizeConfig.widthMultiplier/ heightMultiplier, which this package exports. If you use ButtonsTab, initialize sizing first (e.g. via flutter_screenutil's ScreenUtilInit and calling SizeConfig.init() in its builder) before the icon is built. TextButtonsTab, IconButtonsTab, and IconLabelTab do not require this.