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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 https://appbar.codemagic.app.

convex_bottom_bar is now a Flutter Favorite package!

Here are some supported style:

fixed	react	badge chip
fixedCircle	reactCircle	flip
textIn	titled	tab image
button	fixed 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 :

dependencies:
  convex_bottom_bar: ^latest_version

import 'package:convex_bottom_bar/convex_bottom_bar.dart';

Scaffold(
  bottomNavigationBar: ConvexAppBar(
    items: [
      TabItem(icon: Icons.home, title: 'Home'),
      TabItem(icon: Icons.map, title: 'Discovery'),
      TabItem(icon: Icons.add, title: 'Add'),
      TabItem(icon: Icons.message, title: 'Message'),
      TabItem(icon: Icons.people, title: 'Profile'),
    ],
    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 Version	Package Version	More
>=1.20	>=2.4.0	Since v1.20, the stable version changed the Stack api
<1.20	<=2.3.0	Support for stable version such as v1.17, v1.12 is not going to be updated

Features

• 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

• Theming
• Badge
• Single Button
• Style Hook
• RTL Support
• Custom Example
• FAQ
• Donate

Theming

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

Attributes	Description
backgroundColor	AppBar background
gradient	gradient will override backgroundColor
height	AppBar height
color	tab icon/text color
activeColor	tab icon/text color when selected
curveSize	size of the convex shape
top	top edge of the convex shape relative to AppBar
cornerRadius	draw the background with topLeft and topRight corner; Only work with fixed tab style
style	style to describe the convex shape: fixed, fixedCircle, react, reactCircle, ...
chipBuilder	custom badge builder, use ConvexAppBar.badge for default badge

Badge

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

ConvexAppBar.badge({0: '99+', 1: Icons.assistant_photo, 2: Colors.redAccent},
  items: [
    TabItem(icon: Icons.home, title: 'Home'),
    TabItem(icon: Icons.map, 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.

Scaffold(
  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.

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

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

  @override
  double get activeIconMargin => 10;

  @override
  double get iconSize => 20;

  @override
  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:

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.

Scaffold(
  bottomNavigationBar: ConvexAppBar.builder(
    count: 5,
    backgroundColor: Colors.blue,
    itemBuilder: Builder(),
  )
);

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

Full custom example can be found at example.

FAQ

Please file feature requests and bugs at the issue tracker.

• How to block tab event?
• Crash on flutter dev/beta channel
• Change active tab index programmatically
• Using an image instead of an icon for actionItem
• Is there anyway to remove elevation in the bottom bar?

Donate

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