最近写前端，没有总结flutter的学习进程，现在来总结一下，关于动画，布局，登录，首页，路由，json格式化，下拉刷新，图片加载预览，欢迎页，焦点问题，保活，上传图片，页面信息传递，这些知识点。由于官方文档给的知识点很少，大部分是一些零零散散的API，所以只能通过一些大神的总结去剥离功能性的写法，如果理解不了的话就google，记不住的话就看demo，写多了就记住了，前期国内资源有限大家可以慢慢的学，但是要学，如果你还想做APP的话，flutter以后肯定会有一片天地的，毕竟一套代码三个平台，企业老板会因为成本多多少少青睐的，所以加油~
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附：效果图因为demo有点多，会慢慢补齐，写了三个小时，感谢大家支持
1.animated_container（放大 缩小github：https://github.com/geeklx/flutter_app2/tree/master/app2/animated_container）：AnimationContainer使用要点，必须传入Duration告诉动画的播放时间，当animationContainer接收到一个新的值的时候，会根据老值进行补间动画，例如开始宽高为100，然后给了新值0并setState后，AnimationContainer会让宽高从100逐渐变化到0，其中变化曲线由Curve决定，默认为Curves.linear。其实动画大部分都是封装好的，多写写就会了，实在记不住就看demo，好记性不如个烂笔头。
import 'package:flutter/material.dart';
import 'animated_container_demo.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: 'Flutter Demo',
theme: new ThemeData(
primarySwatch: Colors.blue,
),
home: AnimatedContainerDemo(),
);
}
}
/**
* AnimationContainer使用要点
* 必须传入Duration告诉动画的播放时间
* 当animationContainer接收到一个新的值的时候
* 会根据老值进行补间动画
* 例如开始宽高为100，然后给了新值0并setState后
* AnimationContainer会让宽高从100逐渐变化到0
* 其中变化曲线由Curve决定，默认为Curves.linear
*/
import 'package:flutter/material.dart';
class AnimatedContainerDemo extends StatefulWidget {
@override
_AnimatedContainerDemoState createState() => _AnimatedContainerDemoState();
}
class _AnimatedContainerDemoState extends State{
double _value = 255.0;
_changeValue() => setState(() {
_value = _value == 255.0 ? 80.0 : 255.0;
print(_value);
});
@override
Widget build(BuildContext context) {
return Center(
child: GestureDetector(
onTap: _changeValue, //放大 缩小
child: AnimatedContainer(
curve: Curves.decelerate,
duration: Duration(seconds: 1),
width: _value,
height: _value,
child: FlutterLogo(),
),
),
);
}
}
2.animated_cross_fade（横竖转向动画github:https://github.com/geeklx/flutter_app2/tree/master/app2/animated_cross_fade）：
import 'package:flutter/material.dart';
class AnimatedCrossFadeDemo extends StatefulWidget {
@override
_AnimatedCrossFadeDemoState createState() => _AnimatedCrossFadeDemoState();
}
class _AnimatedCrossFadeDemoState extends State{
bool _first = false;
change() {
setState(() {
_first = _first ? false : true;
});
}
@override
Widget build(BuildContext context) {
return Center(
child: GestureDetector(
onTap: change, // 横竖转向动画
child: AnimatedCrossFade(
duration: const Duration(seconds: 2),
firstChild: const FlutterLogo(
style: FlutterLogoStyle.horizontal,
size: 200.0,
),
secondChild: const FlutterLogo(
style: FlutterLogoStyle.stacked,
size: 200.0,
),
crossFadeState:
_first ? CrossFadeState.showFirst : CrossFadeState.showSecond,
),
),
);
}
}
3.animated_floating_action_bar（悬浮按钮github:https://github.com/geeklx/flutter_app2/tree/master/app2/animated_floating_action_bar）：这个是官方的demo
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: 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 simply save your changes to "hot reload" in a Flutter IDE).
// Notice that the counter didn't reset back to zero; the application
// is not restarted.
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
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() => _MyHomePageState();
}
class _MyHomePageState extends State{
int _counter = 0;
void _incrementCounter() {
setState(() {
// This call to setState tells the Flutter framework that something has
// changed in this State, which causes it to rerun the build method below
// so that the display can reflect the updated values. If we changed
// _counter without calling setState(), then the build method would not be
// called again, and so nothing would appear to happen.
_counter++;
});
}
@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 Scaffold(
appBar: 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: Text(widget.title),
),
body: Center(
// Center is a layout widget. It takes a single child and positions it
// in the middle of the parent.
child: Column(
// Column is also layout widget. It takes a list of children and
// arranges them vertically. By default, it sizes itself to fit its
// children horizontally, and tries to be as tall as its parent.
//
// Invoke "debug painting" (press "p" in the console, choose the
// "Toggle Debug Paint" action from the Flutter Inspector in Android
// Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
// to see the wireframe for each widget.
//
// Column has various properties to control how it sizes itself and
// how it positions its children. Here we use mainAxisAlignment to
// center the children vertically; the main axis here is the vertical
// axis because Columns are vertical (the cross axis would be
// horizontal).
mainAxisAlignment: MainAxisAlignment.center,
children:[
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.display1,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
4.animation_challenge（github:https://github.com/geeklx/flutter_app2/tree/master/app2/animation_challenge）:
home: HeroDemo(),// 添加list item
import 'package:flutter/material.dart';
import 'package:flutter/scheduler.dart' show timeDilation;
class HeroDemo extends StatefulWidget {
@override
_HeroDemoState createState() => _HeroDemoState();
}
class _HeroDemoState extends State{
Listlist;
@override
void initState() {
super.initState();
list = List.generate(20, (index) => "This is no.$index");
}
@override
Widget build(BuildContext context) {
timeDilation = 2.0;
return Scaffold(
appBar: AppBar(
title: Text('Demo1'),
),
body: ListView.builder(
itemCount: list.length,
itemBuilder: (context, index) {
return ListTile(
title: Text(list[index]),
);
}),
floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
floatingActionButton: Hero(
tag: "FloatingActionButton",
child: FloatingActionButton(
backgroundColor: Colors.blue,
onPressed: () => Navigator.of(context)
.push(MaterialPageRoute(builder: (context) => SecondPage())),
child: Icon(Icons.add),
),
),
);
}
}
class SecondPage extends StatefulWidget {
@override
_SecondPageState createState() => _SecondPageState();
}
class _SecondPageState extends State{
final FocusNode focusNode = FocusNode();
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
backgroundColor: Colors.transparent,
elevation: 0.0,
iconTheme: IconThemeData(
color: Colors.black,
),
),
body: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
mainAxisSize: MainAxisSize.max,
children:[
ListView(
shrinkWrap: true,
padding: const EdgeInsets.symmetric(horizontal: 20.0),
children:[
TextField(
autofocus: true,
focusNode: focusNode,
maxLines: 5,
decoration: InputDecoration.collapsed(
hintText: 'What do you want to add now ?'),
),
],
),
],
),
floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
floatingActionButton: Hero(
tag: "FloatingActionButton",
child: Padding(
padding:
const EdgeInsets.only(left: 12.0, right: 12.0, bottom: 6.0),
child: ButtonTheme(
height: 48.0,
minWidth: double.infinity,
child: RaisedButton(
color: Colors.lightBlue,
onPressed: () {},
elevation: 10.0,
child: Icon(
Icons.add,
color: Colors.white,
),
),
),
)),
);
}
}
home: HideBottomBarDemo(),// 滚动隐藏底部导航 动画
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
class HideBottomBarDemo extends StatefulWidget {
@override
_HideBottomBarDemoState createState() => _HideBottomBarDemoState();
}
class _HideBottomBarDemoState extends State
with SingleTickerProviderStateMixin {
AnimationController _animationController;
Animation _animation;
ScrollController _scrollController;
void _judgeScroll() {
if (_scrollController.position.userScrollDirection ==
ScrollDirection.reverse) {
_animationController.forward();
}
if (_scrollController.position.userScrollDirection ==
ScrollDirection.forward) {
_animationController.reverse();
}
}
@override
void initState() {
super.initState();
_animationController =
AnimationController(vsync: this, duration: Duration(milliseconds: 300));
_animation = Tween(begin: 0.0, end: -100.0).animate(CurvedAnimation(
parent: _animationController, curve: Curves.fastOutSlowIn));
_scrollController = ScrollController(keepScrollOffset: true)
..addListener(_judgeScroll);
}
@override
void dispose() {
// TODO: implement dispose
_animationController?.dispose();
_scrollController..removeListener(_judgeScroll);
// 如果销毁ScrollController，keepScrollOffset将置空
// _scrollController?.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Immersive BottomNavigationBar'),
),
body: _buildListView(),
bottomNavigationBar: _buildBottomNavigationBar(context),
);
}
Widget _buildBottomNavigationBar(BuildContext context) {
return AnimatedBuilder(
animation: _animation,
builder: (context, child) {
return Container(
height: 0.0,
child: Stack(
overflow: Overflow.visible,
children:[
Positioned(
bottom: _animation.value, left: 0.0, right: 0.0, child: child)
],
),
);
},
child: BottomNavigationBar(
items: [
BottomNavigationBarItem(icon: Icon(Icons.title), title: Text("home")),
BottomNavigationBarItem(icon: Icon(Icons.title), title: Text("home")),
BottomNavigationBarItem(icon: Icon(Icons.title), title: Text("home")),
BottomNavigationBarItem(icon: Icon(Icons.title), title: Text("home")),
],
type: BottomNavigationBarType.fixed,
),
);
}
Widget _buildListView() => ListView.builder(
controller: _scrollController,
itemBuilder: (context, index) => ListTile(
leading: Icon(Icons.access_alarm),
title: Text("this is index: $index"),
));
}
home: AudioScreen(),// 倒计时 暂时不好写 没理解（官方demo需要后续去看看写法很巧妙）
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_spinkit/flutter_spinkit.dart';
class AudioScreen extends StatefulWidget {
@override
_AudioScreenState createState() => _AudioScreenState();
}
class _AudioScreenState extends State{
Stopwatch stopwatch = Stopwatch();
@override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
color: Colors.orangeAccent.withOpacity(0.2),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children:[
_buildRecordingStatus(),
_buildTimerText(),
_buildButtonRow(context),
],
),
),
);
}
void _stopButtonPressed() {
setState(() {
stopwatch
..stop()
..reset();
});
}
void _rightButtonPressed() {
setState(() {
if (stopwatch.isRunning) {
stopwatch.stop();
} else {
stopwatch.start();
}
});
}
Widget _buildTimerText() {
return Container(
height: 200.0,
child: Center(
child: TimerText(stopwatch: stopwatch),
));
}
Widget _buildRecordingStatus() {
return Container(
height: 100.0,
width: 100.0,
child: stopwatch.isRunning
? Center(
child: SpinKitWave(
color: Colors.black87.withOpacity(0.7),
type: SpinKitWaveType.start),
)
: Image.asset("assets/recorder.png"));
}
Widget _buildButtonRow(BuildContext context) {
return Row(children:[
_buildButton(_stopButtonPressed, Colors.redAccent, context, Icons.stop),
_buildButton(_rightButtonPressed, Colors.blueAccent, context,
stopwatch.isRunning ? Icons.pause : Icons.play_arrow),
]);
}
Widget _buildButton(
VoidCallback callback, Color color, BuildContext context, IconData icon) {
Size size = MediaQuery.of(context).size;
return Container(
width: size.width * 0.5,
alignment: Alignment.center,
child: RaisedButton(
elevation: 0.0,
shape:
RoundedRectangleBorder(borderRadius: BorderRadius.circular(36.0)),
color: color,
onPressed: callback,
child: Container(
width: size.width * 0.5 - 80.0,
height: MediaQuery.of(context).size.width * 0.15,
child: Icon(
icon,
color: Colors.white,
size: 32.0,
),
),
));
}
}
class TimerText extends StatefulWidget {
TimerText({this.stopwatch});
final Stopwatch stopwatch;
TimerTextState createState() => TimerTextState(stopwatch: stopwatch);
}
class TimerTextState extends State{
Timer timer;
final Stopwatch stopwatch;
TimerTextState({this.stopwatch}) {
timer = Timer.periodic(Duration(milliseconds: 30), callback);
}
void callback(Timer timer) {
if (stopwatch.isRunning) {
setState(() {});
}
}
@override
Widget build(BuildContext context) {
final double width = MediaQuery.of(context).size.width;
final TextStyle timerTextStyle = const TextStyle(
fontSize: 60.0,
fontFamily: "Open Sans",
fontWeight: FontWeight.w300,
color: Colors.black87,
);
ListformattedTime =
TimerTextFormatter.format(stopwatch.elapsedMilliseconds);
return Row(
mainAxisAlignment: MainAxisAlignment.center,
children:[
Container(
child: Text(
"${formattedTime[0]}:",
style: timerTextStyle,
),
width: width / 4.0,
),
Container(
child: Text(
"${formattedTime[1]}:",
style: timerTextStyle,
),
width: width / 4.1,
),
Container(
child: Text(
"${formattedTime[2]}",
style: timerTextStyle,
),
width: width / 4.6,
),
],
);
}
}
class TimerTextFormatter {
static Listformat(int milliseconds) {
int hundreds = (milliseconds / 10).truncate();
int seconds = (hundreds / 100).truncate();
int minutes = (seconds / 60).truncate();
String minutesStr = (minutes % 60).toString().padLeft(2, '0');
String secondsStr = (seconds % 60).toString().padLeft(2, '0');
String hundredsStr = (hundreds % 100).toString().padLeft(2, '0');
return [minutesStr, secondsStr, hundredsStr];
// return "$minutesStr:$secondsStr:$hundredsStr";
}
}
home: ImScreen(),// IM 聊天 这里需要注意的是listview滚动会因为item的增加卡顿，目前布局这块没有好的方案，期待官方。
import 'dart:async';
import 'package:flutter/material.dart';
class ImScreen extends StatefulWidget {
@override
_ImScreenState createState() => _ImScreenState();
}
class _ImScreenState extends State{
StreamController _messageController;
TextEditingController _textController;
List _myMessages;
final _myName = "Vadaski";
@override
void initState() {
// TODO: implement initState
super.initState();
_messageController = StreamController();
_textController = TextEditingController();
_myMessages = List();
}
@override
void dispose() {
_textController.dispose();
_messageController.close();
super.dispose();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('IM Challenge'),
centerTitle: true,
),
body: SafeArea(
child: Column(
children:[
Flexible(
child: ListView.builder(
reverse: true,
itemCount: _myMessages.length,
itemBuilder: (context, index) {
return _buildMessageWidget(_myMessages[index], context);
})),
Divider(
height: 1.0,
),
_buildInputWidget(context),
],
),
),
);
}
Widget _buildInputWidget(BuildContext context) {
return SizedBox(
child: Padding(
padding: const EdgeInsets.only(left: 8.0, right: 8.0),
child: Row(
children:[
Flexible(
child: TextField(
decoration:
InputDecoration.collapsed(hintText: "Send your message"),
controller: _textController,
onChanged: onMessageChanged,
onSubmitted: onMessageSubmit,
)),
Container(
margin: const EdgeInsets.symmetric(horizontal: 4.0),
child: StreamBuilder(
initialData: "",
stream: _messageController.stream,
builder: (context, snapshot) {
return IconButton(
icon: Icon(
Icons.send,
color: snapshot.data == ""
? Colors.grey
: Theme.of(context).accentColor,
),
onPressed: () => onMessageSubmit(_textController.text),
);
},
),
)
],
),
),
);
}
Widget _buildMessageWidget(String text, BuildContext context) {
return Container(
margin: const EdgeInsets.symmetric(vertical: 10.0),
width: MediaQuery.of(context).size.width / 2,
child: Row(
crossAxisAlignment: CrossAxisAlignment.start,
children:[
SizedBox(
width: MediaQuery.of(context).size.width / 4,
),
Expanded(
child: Column(
crossAxisAlignment: CrossAxisAlignment.end,
children:[
Text(_myName, style: Theme.of(context).textTheme.subhead),
Container(
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(12.0),
color: Colors.blue.withOpacity(0.2)),
margin: const EdgeInsets.only(top: 5.0),
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Text(
text,
overflow: TextOverflow.fade,
softWrap: true,
),
),
)
],
),
),
Container(
margin: const EdgeInsets.only(right: 16.0, left: 8.0),
child: CircleAvatar(
child: Text(_myName[0]),
),
),
],
),
);
}
onMessageChanged(String message) {
_messageController.sink.add(message);
}
onMessageSubmit(String message) {
_textController.clear();
if (message != "") {
setState(() {
_myMessages.insert(0, message);
});
}
onMessageChanged("");
}
}
home: RotatingScreen(),//
import 'package:flutter/material.dart';
import '../widgets/rotating_bar.dart';
class RotatingScreen extends StatelessWidget {
@override
Widget build(BuildContext context) {
final size = MediaQuery.of(context).size;
return Scaffold(
body: Stack(
children:[
Positioned(
left: size.width / 5,
top: size.height / 3,
child: RotatingBar(
getBackCenter: true,
dx: size.width / 5,
dy: size.height / 3,
style: Style.Touch,
getAngle: (angle) {
print(angle);
},
),
)
],
));
}
}
home: ScrollBackToTop(),// 滚动到顶部 这个比较常用
import 'package:flutter/material.dart';
class ScrollBackToTop extends StatefulWidget {
@override
_ScrollBackToTopState createState() => _ScrollBackToTopState();
}
class _ScrollBackToTopState extends State
with SingleTickerProviderStateMixin {
ScrollController _controller;
@override
void initState() {
super.initState();
_controller = ScrollController();
}
@override
void dispose() {
_controller.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Scroll Back To Top Demo'),
centerTitle: true,
),
body: ListView.builder(
controller: _controller,
itemCount: 100,
itemBuilder: (context, index) {
return ListTile(
title: Center(
child: Text(
'This is no $index',
style: TextStyle(fontSize: 24),
)),
);
}),
floatingActionButton: FloatingActionButton(
onPressed: backToTop,
child: Icon(Icons.vertical_align_top),
),
);
}
backToTop() {
if (_controller.offset != 0)
_controller.animateTo(
0,
duration: Duration(milliseconds: 500),
curve: Curves.easeIn,
);
}
}
5.animation_demo（总结一下各种目前能用的场景化动画github：https://github.com/geeklx/flutter_app2/tree/master/app2/animation_demo）：由于篇幅有限代码就不说了，地址附上 
6.beaytiful_search_bar_demo（搜索栏）：https://github.com/geeklx/flutter_app2/tree/master/app2/beaytiful_search_bar_demo
import 'package:flutter/material.dart';
import 'asset.dart';
class SearchBarDemo extends StatefulWidget {
@override
_SearchBarDemoState createState() => _SearchBarDemoState();
}
class _SearchBarDemoState extends State{
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('SearchBarDemo'),
actions:[
IconButton(
icon: Icon(Icons.search),
onPressed: () =>
showSearch(context: context, delegate: SearchBarDelegate())),
],
),
);
}
}
const searchList = [
"ChengDu",
"ShangHai",
"BeiJing",
"TianJing",
"NanJing",
"ShenZheng"
];
const recentSuggest = [
"suggest1",
"suggest2"
];
class SearchBarDelegate extends SearchDelegate{
@override
ListbuildActions(BuildContext context) {
return [IconButton(icon: Icon(Icons.clear), onPressed: () => query = "")];
}
@override
Widget buildLeading(BuildContext context) {
return IconButton(
icon: AnimatedIcon(
icon: AnimatedIcons.menu_arrow, progress: transitionAnimation),
onPressed: () => close(context, null));
}
@override
Widget buildResults(BuildContext context) {
return Center(child: Container(
width: 100.0,
height: 100.0,
child: Card(
color: Colors.redAccent,
child: Center(
child: Text(query),
),
),
),);
}
@override
Widget buildSuggestions(BuildContext context) {
final suggestionList = query.isEmpty
? recentSuggest
: searchList.where((input) => input.startsWith(query)).toList();
return ListView.builder(
itemCount: suggestionList.length,
itemBuilder: (context, index) => ListTile(
onTap: (){
query = suggestionList[index];
showResults(context);},
title: RichText(
text: TextSpan(
text: suggestionList[index].substring(0, query.length),
style: TextStyle(
color: Colors.black, fontWeight: FontWeight.bold),
children: [
TextSpan(
text: suggestionList[index].substring(query.length),
style: TextStyle(color: Colors.grey))
])),
));
}
}
7.bloc_provider_pattern（监听私有方法调用写法）：https://github.com/geeklx/flutter_app2/tree/master/app2/bloc_provider_pattern
