flutter 屏幕适配

import 'dart:async';
import 'dart:collection';

import 'package:flutter/gestures.dart';
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
import 'dart:ui';


/// Flutter 适配
/// create by Aracoix 
class FlutterDensity extends WidgetsFlutterBinding {
  double weight = 360;
  double getAdapterRatio() {
    return window.physicalSize.width / weight;
  }

  double getAdapterRatioRatio() {
    return getAdapterRatio() / window.devicePixelRatio;
  }

  Size getScreenAdapterSize() {
    return Size(weight, window.physicalSize.height / getAdapterRatio());
  }
  static WidgetsBinding? mInstance;
  static WidgetsBinding ensureInitialized(double weight) {
    mInstance ??= FlutterDensity(weight);
    return mInstance!;
  }

  FlutterDensity(this.weight);

  @override
  ViewConfiguration createViewConfiguration() {
    return ViewConfiguration(
      size: getScreenAdapterSize(),
      devicePixelRatio: getAdapterRatio(),
    );
  }

  ///
  /// 以下一大重写与 GestureBinding
  /// 唯一目的 把 _handlePointerDataPacket 方法 事件原始数据转换 改用
  /// 修改过的 PixelRatio

  @override
  void initInstances() {
    super.initInstances();
    window.onPointerDataPacket = _handlePointerDataPacket;
  }

  @override
  void unlocked() {
    super.unlocked();
    _flushPointerEventQueue();
  }

  final Queue<PointerEvent> _pendingPointerEvents = Queue<PointerEvent>();

  void _handlePointerDataPacket(PointerDataPacket packet) {
    _pendingPointerEvents.addAll(PointerEventConverter.expand(
        packet.data,
        // 适配事件的转换比率,采用我们修改的
        getAdapterRatio()));
    if (!locked) _flushPointerEventQueue();
  }

  @override
  void cancelPointer(int pointer) {
    if (_pendingPointerEvents.isEmpty && !locked)
      scheduleMicrotask(_flushPointerEventQueue);
    _pendingPointerEvents.addFirst(PointerCancelEvent(pointer: pointer));
  }

  void _flushPointerEventQueue() {
    assert(!locked);
    while (_pendingPointerEvents.isNotEmpty)
      _handlePointerEvent(_pendingPointerEvents.removeFirst());
  }

  final Map<int, HitTestResult> _hitTests = <int, HitTestResult>{};

  void _handlePointerEvent(PointerEvent event) {
    assert(!locked);
    HitTestResult? result;
    if (event is PointerDownEvent) {
      assert(!_hitTests.containsKey(event.pointer));
      result = HitTestResult();
      hitTest(result, event.position);
      _hitTests[event.pointer] = result;
      assert(() {
        if (debugPrintHitTestResults) debugPrint('$event: $result');
        return true;
      }());
    } else if (event is PointerUpEvent || event is PointerCancelEvent) {
      result = _hitTests.remove(event.pointer);
    } else if (event.down) {
      result = _hitTests[event.pointer];
    } else {
      return; // We currently ignore add, remove, and hover move events.
    }
    if (result != null) dispatchEvent(event, result);
  }
}

使用时直接使用对应数字

import 'package:flutter/material.dart';
import 'package:flutter_all/flutter_density.dart';

void main() =>
  FlutterDensity.ensureInitialized(375)
    ..attachRootWidget(const MyApp())
    ..scheduleWarmUpFrame();

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

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
            Row(children: [
              Container(width: 375/2,height: 375/2 ,color: Colors.amberAccent,)  ,
              Container(width: 375/2,height: 375/2 ,color: Colors.blue,)
            ],)

          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

360dp

480dp