navigation_bar_m3e #

Material 3 Expressive Navigation Bar for Flutter with badges, pill/underline indicators, and token-driven styling.

• NavigationBarM3E — wrapper around Flutter's NavigationBar with M3E tokens
• NavigationDestinationM3E — destination data (icon, selectedIcon, label, badge)
• NavBadgeM3E — small badge/dot utility for icons

All styling is driven by the m3e_design ThemeExtension (M3ETheme).

Monorepo Layout #

packages/
  m3e_design/
  navigation_bar_m3e/

pubspec.yaml references ../m3e_design.

Usage #

import 'package:navigation_bar_m3e/navigation_bar_m3e.dart';

final items = [
  const NavigationDestinationM3E(
    icon: Icon(Icons.home_outlined),
    selectedIcon: Icon(Icons.home),
    label: 'Home',
  ),
  const NavigationDestinationM3E(
    icon: Icon(Icons.search),
    label: 'Search',
    badgeCount: 3,
  ),
  const NavigationDestinationM3E(
    icon: Icon(Icons.person),
    label: 'Profile',
    badgeDot: true,
  ),
];

NavigationBarM3E(
  destinations: items,
  selectedIndex: 0,
  onDestinationSelected: (i) {},
  labelBehavior: NavBarM3ELabelBehavior.onlySelected,
  indicatorStyle: NavBarM3EIndicatorStyle.pill, // pill | underline | none
  size: NavBarM3ESize.medium,
  density: NavBarM3EDensity.regular,
  shapeFamily: NavBarM3EShapeFamily.round,
);

Tokens mapping #

• Container: surfaceContainerHigh
• Indicator: secondaryContainer (color), pill shape by default; underline style uses a bottom border
• Selected: onSecondaryContainer (icon/label)
• Unselected: onSurfaceVariant
• Label style: labelMedium
• Heights: small ≈64dp, medium ≈80dp
• Icon size: 24dp

Badges #

Use badgeCount for numeric badges or badgeDot: true for a small dot. Colors default to errorContainer / onErrorContainer and can be overridden via NavBadgeM3E.

Accessibility #

• Provide semanticLabel per destination (used as tooltip) or on the bar.
• Label behavior options: alwaysShow, onlySelected, or alwaysHide.

License #

MIT

Live demo (Gallery) #

Explore this component in the M3E Gallery (GitHub Pages):

https://

To run the Gallery locally:

cd apps/gallery
flutter run -d chrome

Last updated: 2025-10-23

Detailed Guide #

What this package provides #

NavigationBarM3E with M3E tokens for colors and shapes, badges, and adaptive layout behavior.

Installation #

• Monorepo (local path): already configured alongside m3e_design.
• Pub (when published):

dependencies:
  navigation_bar_m3e: ^0.1.0
  m3e_design: ^0.1.0

Minimum SDK: Dart >=3.5.0; Flutter >=3.22.0.

Dependencies #

• flutter
• m3e_design

Quick start #

int index = 0;

NavigationBarM3E(
  selectedIndex: index,
  onDestinationSelected: (i) => setState(() => index = i),
  destinations: const [
    NavigationDestinationM3E(icon: Icon(Icons.home), label: 'Home'),
    NavigationDestinationM3E(icon: Icon(Icons.search), label: 'Search'),
    NavigationDestinationM3E(icon: Icon(Icons.person), label: 'Profile'),
  ],
)

Key parameters #

• destinations: List
• selectedIndex: int — Current selection.
• onDestinationSelected: ValueChanged
• badgeBuilder / badgeCount: Optional badges per destination.
• backgroundColor / indicatorColor: Color? — Override token-driven colors.
• height / labelBehavior: Layout tweaks.

Theming with m3e_design #

Colors/shape/typography adapt from the active M3ETheme extension.

Accessibility #

• Labels visible or via semantics; badges have semantics descriptions.

Links #

• Repository: https://github.com/EmilyMoonstone/material_3_expressive/tree/main/packages/navigation_bar_m3e
• Issue tracker: https://github.com/EmilyMonestone/material_3_expressive/issues
• Changelog: ./CHANGELOG.md