flutter 基本操作

1. 获取一个uuid

//https://pub.dev/packages/uuid

//在pubspec.yaml中添加
dependencies:
  uuid: 2.2.2
//引入文件，设置变量，生成uuid
import 'package:uuid/uuid.dart';
var uuid = Uuid();
uuid.v4();

2. 获取设备横竖方向， 尺寸，DPR

//Orientation.landscape or Orientation.portrait
MediaQuery.of(context).orientation

MediaQuery.of(context).size.width
MediaQuery.of(context).size.height

MediaQuery.of(context).devicePixelRatio

3. 获取父元素的尺寸

    return LayoutBuilder(
      builder: (context, constraints) {
        return Container(
          width: constraints.maxWidth / 2,
          height: constraints.maxHeight / 2,
          color: Colors.red,
        );
      },
    );