进度条

进度条代码：

直线进度条和圆圈进度环，用法一样，里边都有个参数value这个就是进度，从0-1。下面就是一个完整的示例：

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: HomePage(),
      ),
    );
  }
}

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  var _currentvalue=0.0;
  @override
  Widget build(BuildContext context) {
    return Center(
      child: Column(
        children: <Widget>[
          Padding(
            padding: EdgeInsets.only(top:100,bottom: 100,),
            child: LinearProgressIndicator(
              value: _currentvalue,
              backgroundColor: Colors.deepOrange,
                valueColor: AlwaysStoppedAnimation(Colors.lightGreen),
            ),
          ),
          CircularProgressIndicator(
            value:_currentvalue,
          ),
          GestureDetector(
            onTap: (){setState(() {
              if(_currentvalue>=1.0){
                _currentvalue=0.01;
              }else{
                _currentvalue+=0.01;
              }
            });},
            child: Image.network(
              'http://www.ecobentech.com/img/a.jpg',
              width: 100.0,
              height: 200.0,
            ),
          ),
        ],
      ),
    );
  }
}