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The official BottomAppBar can only display a notch FAB with an app bar, and sometimes we need a convex FAB. BottomAppBar and NotchShape's implementation inspires this ConvexAppBar.

Online example can be found at

convex_bottom_bar is now a Flutter Favorite package!

Here are some supported style:

fixedreactbadge chip
textIntitledtab image
buttonfixed corner

How to use

Typically ConvexAppBar can work with Scaffold by setup its bottomNavigationBar.

The ConvexAppBar has two constructors. The ConvexAppBar() will use the default style to simplify the tab creation.

Add this to your package's pubspec.yaml file, use the latest version Pub:

  convex_bottom_bar: ^latest_version
import 'package:convex_bottom_bar/bottom_bar_fix.dart';

  bottomNavigationBar: ConvexAppBar(
    items: [
      TabItem(icon: Icons.home, title: 'Home'),
      TabItem(icon:, title: 'Discovery'),
      TabItem(icon: Icons.add, title: 'Add'),
      TabItem(icon: Icons.message, title: 'Message'),
      TabItem(icon: Icons.people, title: 'Profile'),
    initialActiveIndex: 2,//optional, default as 0
    onTap: (int i) => print('click index=$i'),

Flutter Version Support
As Flutter is developing fast. There can be breaking changes. We will be trying to support the stable version and beta version through different package versions.

Stable Flutter VersionPackage VersionMore
>=1.20>=2.4.0Since v1.20, the stable version changed the Stack api
<1.20<=2.3.0Support for stable version such as v1.17, v1.12 is not going to be updated


  • Provide multiple internal styles
  • Ability to change the theme of AppBar
  • Provide builder API to customize a new style
  • Add badge on the tab menu
  • Elegant transition animation
  • Provide hook API to override some of the internal styles
  • RTL support

Table of contents


The bar will use default style, you may want to theme it. Here are some supported attributes:

backgroundColorAppBar background
gradientgradient will override backgroundColor
heightAppBar height
colortab icon/text color
activeColortab icon/text color when selected
curveSizesize of the convex shape
toptop edge of the convex shape relative to AppBar
cornerRadiusdraw the background with topLeft and topRight corner; Only work with fixed tab style
stylestyle to describe the convex shape: fixed, fixedCircle, react, reactCircle, ...
chipBuildercustom badge builder, use ConvexAppBar.badge for default badge


If you need to add a badge on the tab, use the ConvexAppBar.badge to get it done.

badge demo

ConvexAppBar.badge({0: '99+', 1: Icons.assistant_photo, 2: Colors.redAccent},
  items: [
    TabItem(icon: Icons.home, title: 'Home'),
    TabItem(icon:, title: 'Discovery'),
    TabItem(icon: Icons.add, title: 'Add'),
  onTap: (int i) => print('click index=$i'),

The badge() method accepts an array of badges; The badges is a map with tab items. Each value of entry can be either String, IconData, Color or Widget.

Single Button

If you only need a single button, checkout the ConvexButton.


  appBar: AppBar(title: const Text('ConvexButton Example')),
  body: Center(child: Text('count $count')),
  bottomNavigationBar: ConvexButton.fab(
    onTap: () => setState(() => count++),

Style Hook

Hook for internal tab style. Unlike the ConvexAppBar.builder, you may want to update the tab style without defining a new tab style.

This hook is limited and can lead to overflow broken if the size you provide does not match with internal style.

  style: Style(),
  child: ConvexAppBar(
    initialActiveIndex: 1,
    height: 50,
    top: -30,
    curveSize: 100,
    style: TabStyle.fixedCircle,
    items: [
      TabItem(icon: Icons.import_contacts),
      TabItem(title: "2020", icon:,
    backgroundColor: _tabBackgroundColor,
class Style extends StyleHook {
  double get activeIconSize => 40;

  double get activeIconMargin => 10;

  double get iconSize => 20;

  TextStyle textStyle(Color color) {
    return TextStyle(fontSize: 20, color: color);

RTL Support

RTL is supported internally, and if you define the TextDirection inside the app, the AppBar should work fine. Both RTL and LTR can be configured through Directionality:

  textDirection: TextDirection.rtl,
  child: Scaffold(body:ConvexAppBar(/*TODO ...*/)),

Custom Example

If the default style does not match your situation, try with ConvexAppBar.builder(), allowing you to custom nearly all the tab features.

  bottomNavigationBar: ConvexAppBar.builder(
    count: 5,
    style: TabStyle.fixed,
    itemBuilder: Builder(),

// user defined class
class Builder extends DelegateBuilder {
  Widget build(BuildContext context, int index, bool active) {
    return Text('TAB $index');

Full custom example can be found at example.


Please file feature requests and bugs at the issue tracker.


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