flutter_optimize/lib/two.dart

import 'dart:async';

import 'package:flutter/material.dart';

class Two extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return _TwoState();
  }
}

class CountText extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return _CountTextState();
  }
}

class _CountTextState extends State<CountText> {
  int _count = 0;
  Timer _timer;

  @override
  void initState() {
    super.initState();
    Timer.periodic(Duration(milliseconds: 1000), (t) {
      setState(() {
        _count++;
      });
    });
  }

  @override
  void dispose() {
    if (_timer != null && _timer.isActive) {
      _timer.cancel();
    }
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Text(
      _count.toString(),
      style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
    );
  }
}

class _TwoState extends State<Two> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text("性能测试2"),
        ),
        body: Column(
          children: <Widget>[
            Container(
              margin: EdgeInsets.fromLTRB(10, 10, 10, 5),
              height: 100,
              color: Colors.amberAccent,
            ),
            Container(
              margin: EdgeInsets.fromLTRB(10, 10, 10, 5),
              height: 100,
              color: Colors.blue,
            ),
            Container(
              height: 100,
              child: ListView.builder(
                  scrollDirection: Axis.horizontal,
                  itemCount: 12,
                  itemBuilder: (context, index) {
                    return Container(
                        width: 70,
                        height: 70,
                        child: Image.asset(
                          "assets/2.png",
                          width: 50,
                          height: 50,
                        ));
                  }),
            ),
            Container(
              height: 100,
              margin: EdgeInsets.fromLTRB(10, 10, 10, 5),
              color: Colors.yellow,
              child: Center(child: CountText()),
            )
          ],
        ),
      ),
    );
  }
}