bottom_nav_layout 3.0.1

A quick and powerful app layout. Supports page state preservation, lazy page loading, and has a page backstack.

Demo

What is bottom_nav_layout?

It is a quick flutter app layout for building an app with a bottom nav bar. You can get an app with fluent behavior running in 15 lines of code.

Why bottom_nav_layout?

• Eliminates all boilerplate code for bottom nav bar coordination.
• Offers additional common features.
  • Page state preservation
  • Lazy page loading
  • Page transition animations
  • In-page navigation
  • Back button navigation for Android
• Works with any bottom bar you want. Use the material or cupertino bottom bar, grab one from pub.dev or use your own.

Content

• Usage
• Page State Preservation
• Lazy Page Loading
• Page Back Stack
• In-Page Navigation
• Different Bottom Bars
• Improvements
• Community

Usage

Installation

Add the following to your pubspec.yaml file.

dependencies:
  bottom_nav_layout: latest_version

Quick Start Example

import 'package:bottom_nav_layout/bottom_nav_layout.dart';

void main() => runApp(MaterialApp(
      home: BottomNavLayout(
        // The app's destinations
        pages: [
          (_) => Center(child: Text("Welcome to bottom_nav_layout")),
          (_) => SliderPage(),
          (_) => Center(child: TextField(decoration: InputDecoration(hintText: 'Go..'))),
        ],
        bottomNavigationBar: (currentIndex, onTap) => BottomNavigationBar(
          currentIndex: currentIndex,
          onTap: (index) => onTap(index),
          items: [
            BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Home'),
            BottomNavigationBarItem(icon: Icon(Icons.linear_scale), label: 'Slider'),
            BottomNavigationBarItem(icon: Icon(Icons.search), label: 'Search'),
          ],
        ),
      ),
    ));

Done. You have a complete, working application.

SliderPage code

Parameters

Name	Description	Default
pages	The app's destinations.	N/A
bottomNavigationBar	The bottom navbar of the layout.	N/A
savePageState	When false, the pages are reinitialized every time they are navigated. (Material behavior). When true, the pages are initialized once and hidden/shown on navigation. (Cupertino behavior)	false
lazyLoadPages	When false, pages are created in the beginning. When true, pages are created when they are navigated for the first time.	false
pageStack	Navigation stack that remembers pages visited. Enhances back button management on Android.	ReorderToFrontPageStack for Android, NoPageStack for iOS
extendBody	Passed to Scaffold.extendBody.	false
resizeToAvoidBottomInset	Passed to Scaffold.resizeToAvoidBottomInset.	true
pageTransitionData	Animation configuration for page transitions.	null

Inner Widget Tree

Page State Preservation

The state changes you made in a page such as scroll amount, sub-navigation, form inputs etc. are preserved. You can enable it as per Cupertino Design Guidelines or disable it as per Material Design Guidelines

savePageState: true, // Default is false

Lazy Page Loading

The layout offers the option to lazily create the pages using the passed in page builders. When lazyLoadPages is set to true, the pages are not created until they are navigated to for the first time. This is useful when a non-initial page;

• Has a load animation.
• Runs a heavy process that is not needed until the page is opened.

lazyLoadPages: true, // Default is false

Page Back Stack

The layout remembers the order of pages navigated and when back button is pressed, navigates back to the previously navigated page.

There are many useful page back stack behaviors implemented such as reorder-to-front and replace-except-first. You can also implement your own.

You also specify the initialPage inside PageStack.

// Default is ReorderToFrontPageStack for Android and NoPageStack for iOS.
pageStack: ReorderToFrontPageStack(initialPage: 0),

Page Back Stack Documentation for details.

In-Page Navigation

The layout can manage flat navigation pattern.

Figure: Flat Navigation

Benefits

1. Android back button navigates both in-page and among pages.
2. Bottom bar pops all in-page stack when the current bar item is reselected.

To do this, the page should have a Navigator widget that use the passed in GlobalKey as its key.

In-Page Navigation Documentation for more information.

Different Bottom Bars

So far, we only worked on Material bottom nav bar. The layout supports any bottom bar.

Example usage of flutter_snake_navigationbar:

bottomNavigationBar: (currentIndex, onTap) => SnakeNavigationBar.color(
  currentIndex: currentIndex,
  onTap: (index) => onTap(index),
  items: [
    BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Home'),
    BottomNavigationBarItem(icon: Icon(Icons.linear_scale), label: 'Slider'),
    BottomNavigationBarItem(icon: Icon(Icons.search), label: 'Search'),
  ],
),

Improvements

• I am planning to add page transition animations.
• Tell me if you want to see a feature your app has/needs in this package. I will do my best to integrate it.
• I am also considering to make a drawer_nav_layout package. If you are interested, let me know!

Community

Any feedback is appreciated. 🚀🚀

I love talking about code. Find me on discord at ViraL#2868

If you have queries, feel free to create an issue.

If you would like to contribute, feel free to create a PR.