脚手架主体中的多个Gridview生成器
在我看来,我们必须添加多个垂直网格视图,从数据库加载数据 问题是,当我在列或包裹中添加GridView时,会出现一个错误,因为高度不固定。脚手架主体中的多个Gridview生成器,gridview,flutter,dart,Gridview,Flutter,Dart,在我看来,我们必须添加多个垂直网格视图,从数据库加载数据 问题是,当我在列或包裹中添加GridView时,会出现一个错误,因为高度不固定。 如何在正文中添加多个Gridview?使用容器换行,同时检查高度和收缩换行:true,以下示例演示Gridview.builder和Gridview.count 完整代码 import 'package:flutter/material.dart'; void main() => runApp(MyApp()); class MyApp exten
如何在正文中添加多个Gridview?使用容器换行,同时检查高度和收缩换行:true,以下示例演示Gridview.builder和Gridview.count
完整代码
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<MyHomePage> {
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++;
});
}
List<String> data = ["abc", "def", "kkk","aaa", "abc", "def", "kkk","aaa", "abc", "def", "kkk","aaa", "abc", "def", "kkk","aaa", "abc", "def", "kkk","aaa"];
@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: SingleChildScrollView(
child: Column(
children: <Widget>[
Container(
height: 300,
color: Colors.white30,
child: GridView.count(
shrinkWrap: true,
crossAxisCount: 4,
childAspectRatio: 1.0,
padding: const EdgeInsets.all(4.0),
mainAxisSpacing: 4.0,
crossAxisSpacing: 4.0,
children: <String>[
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
].map((String url) {
return GridTile(
child: Image.network(url, fit: BoxFit.cover));
}).toList()),
),
Container(
height: 300,
color: Colors.white30,
child: GridView.builder(
shrinkWrap: true,
itemCount: data.length,
gridDelegate: new SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 2),
itemBuilder: (BuildContext context, int index) {
return new Card(
child: new GridTile(
//footer: new Text(data[index]),
child: new Text(data[index]), //just for testing, will fill with image later
),
);
},
),
)
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
导入“包装:颤振/材料.省道”;
void main()=>runApp(MyApp());
类MyApp扩展了无状态小部件{
//此小部件是应用程序的根。
@凌驾
小部件构建(构建上下文){
返回材料PP(
标题:“颤振演示”,
主题:主题数据(
//这是应用程序的主题。
//
//尝试使用“flutter run”运行应用程序。您将看到
//应用程序有一个蓝色工具栏。然后,在不退出应用程序的情况下,重试
//将下面的primarySwatch更改为Colors.green,然后调用
//“热重新加载”(在运行“颤振运行”的控制台中按“r”,
//或者只需将更改保存到颤振IDE中的“热重新加载”。
//请注意,计数器没有重置回零;应用程序
//未重新启动。
主样本:颜色。蓝色,
),
主页:MyHomePage(标题:“颤振演示主页”),
);
}
}
类MyHomePage扩展StatefulWidget{
MyHomePage({Key,this.title}):超级(Key:Key);
//此小部件是应用程序的主页。它是有状态的,表示
//它有一个状态对象(定义如下),其中包含影响
//看起来怎么样。
//此类是状态的配置。它保存值(在此
//案例名称)由家长(在本例中为应用程序小部件)提供,以及
//由State的build方法使用。小部件子类中的字段包括
//始终标记为“最终”。
最后的字符串标题;
@凌驾
_MyHomePageState createState()=>\u MyHomePageState();
}
类_MyHomePageState扩展状态{
int _计数器=0;
void _incrementCounter(){
设置状态(){
//这个对setState的调用告诉颤振框架,某些东西
//已在此状态下更改,这将导致它重新运行下面的生成方法
//以便显示能够反映更新的值。如果我们更改
//_计数器,而不调用setState(),则生成方法将不可用
//再打一次电话,似乎什么也没发生。
_计数器++;
});
}
列表数据=[“abc”、“def”、“kkk”、“aaa”、“abc”、“def”、“kkk”、“aaa”、“abc”、“def”、“kkk”、“aaa”、“abc”、“def”、“kkk”、“aaa”、“abc”、“def”、“kkk”、“aaa”];
@凌驾
小部件构建(构建上下文){
//每次调用setState时都会重新运行此方法,例如,按done
//通过上面的_incrementCounter方法。
//
//对颤振框架进行了优化,以制定重新运行的构建方法
//快速,这样你就可以重建任何需要更新的东西
//而不是必须单独更改小部件的实例。
返回脚手架(
appBar:appBar(
//在这里,我们从MyHomePage对象中获取由创建的值
//使用App.build方法,并使用它设置appbar标题。
标题:文本(widget.title),
),
正文:SingleChildScrollView(
子:列(
儿童:[
容器(
身高:300,
颜色:Colors.white30,
子项:GridView.count(
收缩膜:对,
交叉轴计数:4,
childAspectRatio:1.0,
填充:常数边集全部(4.0),
主轴间距:4.0,
交叉轴间距:4.0,
儿童:[
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
'https://www.fnordware.com/superpng/pngtest16rgba.png',
].map((字符串url){
返回网格(
子:Image.network(url,fit:BoxFit.cover));
}).toList()),
),
容器(
身高:300,
颜色:Colors.white30,
子项:GridView.builder(
收缩膜:对,
itemCount:data.length,
gridDelegate:新SliverGridDelegateWithFixedCrossAxisCount(
交叉轴计数:2),
itemBuilder:(构建上下文,int索引){
归还新卡(
孩子:新格子(
//页脚:新文本(数据[索引]),
child:newtext(data[index]),//仅用于测试,稍后将用图像填充
),
);
},
),
)
],
),
),
浮标
Container(
child: listCat.length != 0
? GridView.builder(
scrollDirection: Axis.vertical,
physics: NeverScrollableScrollPhysics(),
itemCount: listCat.length <= 0 ? 0 : listCat.length,
primary: true,
shrinkWrap: true,
addAutomaticKeepAlives: true,
padding: EdgeInsets.all(0),
gridDelegate:
new SliverGridDelegateWithFixedCrossAxisCount(
mainAxisSpacing: 2,
crossAxisSpacing: 3,
crossAxisCount: 4,
childAspectRatio: MediaQuery.of(context)
.size
.width /
(MediaQuery.of(context).size.height /
1.5)),
itemBuilder: (BuildContext context, int index) =>
_makeElementCat(index),
)
: Center(
child: SpinKitFadingFour(
color: Colors.green,
size: 50.0,
),
),
),