flutter 屏幕适配

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: LayoutBuilder(
          builder: (context, constraints) {
            return Container(
              width: constraints.maxWidth * 0.8,
              height: constraints.maxHeight * 0.5,
              color: Colors.blue,
              child: Center(
                child: Text('Responsive Layout'),
              ),
            );
          },
        ),
      ),
    );
  }
}

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: Text(
            'Hello, Flutter!',
            style: TextStyle(
              fontSize: MediaQuery.of(context).textScaleFactor * 20,
            ),
          ),
        ),
      ),
    );
  }
}

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: Image.asset(
            'assets/images/example.png',
            fit: BoxFit.cover,
          ),
        ),
      ),
    );
  }
}