pull_to_refresh 1.0.2

a widget provided to the flutter scroll component drop-down refresh and pull up load.

example/lib/main.dart

import 'dart:async';

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter/scheduler.dart';
import 'package:pull_to_refresh/pull_to_refresh.dart';

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

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Pulltorefresh Demo',
      theme: new ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or press Run > Flutter Hot Reload in IntelliJ). Notice that the
        // counter didn't reset back to zero; the application is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: new MyHomePage(title: 'Pulltorefresh'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

  @override
  _MyHomePageState createState() => new _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  RefreshMode loading=RefreshMode.idel, refreshing=RefreshMode.idel;

  List<Widget> _getDatas() {
    List<Widget> data = [];
    for (int i = 0; i < 24; i++) {
      data.add(new Text('Data $i'));
    }
    return data;
  }

  Widget _buildHeader(context, mode) {
    return new Image.asset(
      "images/animate.gif",
      height: 100.0,
      fit: BoxFit.cover,
    );
  }




  void _onModeChange(isUp,mode){
      if(isUp){
        //must be do it
        setState(() {
          refreshing = mode;
        });
        // this is equals onRefresh()
        if(mode==RefreshMode.refreshing) {
          new Future.delayed(const Duration(milliseconds: 2000), () {
            setState(() {
              refreshing = RefreshMode.failed;
            });
            print("Refreshed!!!");
          });
        }
      }
      else{
        //must be do it
        setState(() {
          loading= mode;
        });
        // this is equals onLoaadmore()
        if(mode==RefreshMode.refreshing) {
          new Future<Null>.delayed(const Duration(milliseconds: 2000), () {
            setState(() {
              loading = RefreshMode.failed;
            });
            print("LoadComplete!!!");
          });
        }
      }
  }

  void _onOffsetCallback(double offset) {
    // if you want change some widgets state ,you should rewrite the callback
//    print(offset);
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return new Scaffold(
        appBar: new AppBar(
          // Here we take the value from the MyHomePage object that was created by
          // the App.build method, and use it to set our appbar title.
          title: new Text(widget.title),
        ),
        body: new Container(
          child: new SmartRefresher(
            enablePulldownRefresh: true,
            enablePullUpLoad: true,
            headerBuilder: _buildHeader,
            refreshMode: this.refreshing,
            loadMode: this.loading,
            child: new ListView(
                physics: const NeverScrollableScrollPhysics(),
                shrinkWrap: true,
                itemExtent: 40.0,
                children: _getDatas()),
            onModeChange: _onModeChange,
            onOffsetChange: _onOffsetCallback,
          ),
        ));
  }
}