Building adaptive apps

main.dart

import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return  MaterialApp(
      title: 'Adaptive Screen',
      home: const AdaptiveScreen(),
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.blueAccent),
        useMaterial3: true,
      ),
    );
  }
}


class AdaptiveScreen extends StatefulWidget {
  const AdaptiveScreen({Key? key}) : super(key: key);

  @override
  AdaptiveScreenState createState() => AdaptiveScreenState();
}

class AdaptiveScreenState extends State<AdaptiveScreen> {


  int _selectedIndex = 0;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("Responsive and Adaptive"),
      ),
      bottomNavigationBar:  MediaQuery.of(context).size.width < 640?
      BottomNavigationBar(
          currentIndex: _selectedIndex,
          unselectedItemColor: Colors.grey,
          selectedItemColor: Colors.indigoAccent,
          // called when one tab is selected
          onTap: (int index) {
            setState(() {
              _selectedIndex = index;
            });
          },
          // bottom tab items
          items: const [
            BottomNavigationBarItem(
                icon: Icon(Icons.home), label: 'Home'),
            BottomNavigationBarItem(
                icon: Icon(Icons.feed), label: 'Feed'),
            BottomNavigationBarItem(
                icon: Icon(Icons.favorite), label: 'Favorites'),
            BottomNavigationBarItem(
                icon: Icon(Icons.settings), label: 'Settings')
          ]):null,
      body: Row(
        children: [
          if (MediaQuery.of(context).size.width >= 640)
            NavigationRail(
              onDestinationSelected: (int index) {
                setState(() {
                  _selectedIndex = index;
                });
              },
              selectedIndex: _selectedIndex,
              destinations: const [
                NavigationRailDestination(
                    icon: Icon(Icons.home), label: Text('Home')),
                NavigationRailDestination(
                    icon: Icon(Icons.feed), label: Text('Feed')),
                NavigationRailDestination(
                    icon: Icon(Icons.favorite), label: Text('Favorites')),
                NavigationRailDestination(
                    icon: Icon(Icons.settings), label: Text('Settings')),
              ],

              labelType: NavigationRailLabelType.all,
              selectedLabelTextStyle: const TextStyle(
                color: Colors.teal,
              ),

              unselectedLabelTextStyle: const TextStyle(),
              // Called when one tab is selected
              leading: const Column(
                children: [
                  SizedBox(
                    height: 8,
                  ),
                  CircleAvatar(
                    radius: 20,
                    child: Icon(Icons.person),
                  ),
                ],
              ),

            ),
        const Expanded(child: MyResponsiveGridImage())
        ],
      ),

    );
  }
}

//..................................................................................
class MyResponsiveGridImage extends StatelessWidget {
  const MyResponsiveGridImage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {

    final textTheme = Theme.of(context)
        .textTheme
        .apply(displayColor: Theme.of(context).colorScheme.onSurface);

    // Set the default number of columns to 3.
    int columnsCount = 3;

    // Use the ResponsiveUtils class to determine the device's screen size.
    if (ResponsiveUtils.isMobile(context)) {
      columnsCount = 2;
    } else if (ResponsiveUtils.isDesktop(context)) {
      columnsCount = 5;
    }

    // Build the grid view using the number of columns.
    return Scaffold(
      /*appBar: AppBar(
        title: const Text('Responsive Grid View'),
      ),*/
      body:
      GridView.builder(
        // Set padding and spacing between cards.
        padding: const EdgeInsets.all(10),
        gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
          // Set the number of columns based on the device's screen size.
          crossAxisCount: columnsCount,
          // Set the aspect ratio of each card.
          childAspectRatio: 3 / 2,
          crossAxisSpacing: 10,
          mainAxisSpacing: 10,
        ),
        // Set the number of items in the grid view.
        itemCount: 20,
        itemBuilder: (BuildContext context, int index) {
          // Build each card in the grid view.
          return Card(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: [
                const Expanded(
                  // Add an image to each card.
                  child:
                  Icon(Icons.category),
                  /* Image.asset('assets/images/test.webp',
                    fit: BoxFit.cover,
                  ),*/
                  /* Image.network(
                    'https://picsum.photos/id/$index/400/300',
                    fit: BoxFit.cover,
                  ),*/
                ),
                const SizedBox(height: 10),
                Padding(
                  padding: const EdgeInsets.symmetric(horizontal: 10),
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      // Add a title to each card.
                      Text(
                        'Item $index', style: textTheme.titleMedium!.copyWith(fontWeight: FontWeight.bold), ),
                      const SizedBox(height: 5),
                      // Add a description to each card.
                      Text(
                          'Description of item $index', style: textTheme.bodyMedium!),
                    ],
                  ),
                ),
                const SizedBox(height: 10),
              ],
            ),
          );
        },
        // Set the grid view to shrink wrap its contents.
        shrinkWrap: true,
        // Disable scrolling in the grid view.
        //physics: const NeverScrollableScrollPhysics(),
      ),


    );
  }
}

//..................................................................................
class ResponsiveUtils {
  // Check if the device is considered as mobile based on screen width.
  static bool isMobile(BuildContext context) =>
      MediaQuery.of(context).size.width <= 600;

  // Check if the device is considered as tablet based on screen width.
  static bool isTablet(BuildContext context) =>
      MediaQuery.of(context).size.width > 600 &&
          MediaQuery.of(context).size.width <= 1200;

  // Check if the device is considered as desktop based on screen width.
  static bool isDesktop(BuildContext context) =>
      MediaQuery.of(context).size.width > 1200;
}