颤动 - 布置网格

Question

我试图在颤动中布置一个4x4网格的瓷砖.我设法用列和行来做.但现在我找到了GridView组件.任何人都可以举例说明如何使用它吗？

我无法真正地围绕着文档.我似乎没有得到我想要的结果.

谢谢 :)

Answer 1

GridView用于实现材料网格列表.如果你知道你有一个固定数量的物品并且它不是很多(16个很好),你可以使用GridView.count.但是,您应该注意a GridView是可滚动的,如果这不是您想要的,那么只使用行和列可能会更好.

import 'dart:collection';
import 'package:flutter/scheduler.dart';
import 'package:flutter/material.dart';
import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter/foundation.dart';

void main() {
  runApp(new MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Flutter Demo',
      theme: new ThemeData(
        primarySwatch: Colors.orange,
      ),
      home: new MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget{
  @override
  Widget build(BuildContext context){
    return new Scaffold(
      appBar: new AppBar(
        title: new Text('Grid Demo'),
      ),
      body: new GridView.count(
        crossAxisCount: 4,
        children: new List<Widget>.generate(16, (index) {
          return new GridTile(
            child: new Card(
              color: Colors.blue.shade200,
              child: new Center(
                child: new Text('tile $index'),
              )
            ),
          );
        }),
      ),
    );
  }
}

Answer 2

将图像加载到图块中的简单示例.

import 'package:flutter/material.dart';

void main() {
  runApp( MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Container(

      color: Colors.white30,
      child: GridView.count(
          crossAxisCount: 4,
          childAspectRatio: 1.0,
          padding: const EdgeInsets.all(4.0),
          mainAxisSpacing: 4.0,
          crossAxisSpacing: 4.0,
          children: <String>[
            'http://www.for-example.org/img/main/forexamplelogo.png',
            'http://www.for-example.org/img/main/forexamplelogo.png',
            'http://www.for-example.org/img/main/forexamplelogo.png',
            'http://www.for-example.org/img/main/forexamplelogo.png',
            'http://www.for-example.org/img/main/forexamplelogo.png',
            'http://www.for-example.org/img/main/forexamplelogo.png',
            'http://www.for-example.org/img/main/forexamplelogo.png',
            'http://www.for-example.org/img/main/forexamplelogo.png',
            'http://www.for-example.org/img/main/forexamplelogo.png',
            'http://www.for-example.org/img/main/forexamplelogo.png',
            'http://www.for-example.org/img/main/forexamplelogo.png',
          ].map((String url) {
            return GridTile(
                child: Image.network(url, fit: BoxFit.cover));
          }).toList()),
    );
  }
}

Flutter Gallery应用程序包含一个真实世界的示例,可在此处找到.

Answer 3

请访问此回购.

Widget _gridView() {
    return GridView.count(
      crossAxisCount: 4,
      padding: EdgeInsets.all(4.0),
      childAspectRatio: 8.0 / 9.0,
      children: itemList
          .map(
            (Item) => ItemList(item: Item),
          )
          .toList(),
    );
  }

截图下方包含crossAxisCount:2

Answer 4

使用适合您需要的任何东西。

1. GridView.count(...)

   GridView.count(
     crossAxisCount: 2,
     children: <Widget>[
       FlutterLogo(),
       FlutterLogo(),
       FlutterLogo(),
       FlutterLogo(),
     ],
   )
   

2. GridView.builder(...)

   GridView.builder(
     gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 2),
     itemBuilder: (_, index) => FlutterLogo(),
     itemCount: 4,
   )
   

3. GridView(...)

   GridView(
     gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 2),
     children: <Widget>[
       FlutterLogo(),
       FlutterLogo(),
       FlutterLogo(),
       FlutterLogo(),
     ],
   )
   

4. GridView.custom(...)

   GridView.custom(
     gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 2),
     childrenDelegate: SliverChildListDelegate(
       [
         FlutterLogo(),
         FlutterLogo(),
         FlutterLogo(),
         FlutterLogo(),
       ],
     ),
   )
   

5. GridView.extent(...)

   GridView.extent(
     maxCrossAxisExtent: 400,
     children: <Widget>[
       FlutterLogo(),
       FlutterLogo(),
       FlutterLogo(),
       FlutterLogo(),
     ],
   )
   

输出（全部相同）：

Answer 5

GridView针对不同情况的命名构造函数很少，

建设者

1. GridView
2. GridView.builder
3. GridView.count
4. GridView.custom
5. GridView.extent

以下是GridView构造函数的示例：

import 'package:flutter/material.dart';

void main() => runApp(
  MaterialApp(
    home: ExampleGrid(),
  ),
);

class ExampleGrid extends StatelessWidget {
  List<String> images = [
    "https://uae.microless.com/cdn/no_image.jpg",
    "https://images-na.ssl-images-amazon.com/images/I/81aF3Ob-2KL._UX679_.jpg",
    "https://www.boostmobile.com/content/dam/boostmobile/en/products/phones/apple/iphone-7/silver/device-front.png.transform/pdpCarousel/image.jpg",
    "https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSgUgs8_kmuhScsx-J01d8fA1mhlCR5-1jyvMYxqCB8h3LCqcgl9Q",
    "https://ae01.alicdn.com/kf/HTB11tA5aiAKL1JjSZFoq6ygCFXaw/Unlocked-Samsung-GALAXY-S2-I9100-Mobile-Phone-Android-Wi-Fi-GPS-8-0MP-camera-Core-4.jpg_640x640.jpg",
    "https://media.ed.edmunds-media.com/gmc/sierra-3500hd/2018/td/2018_gmc_sierra-3500hd_f34_td_411183_1600.jpg",
    "https://hips.hearstapps.com/amv-prod-cad-assets.s3.amazonaws.com/images/16q1/665019/2016-chevrolet-silverado-2500hd-high-country-diesel-test-review-car-and-driver-photo-665520-s-original.jpg",
    "https://www.galeanasvandykedodge.net/assets/stock/ColorMatched_01/White/640/cc_2018DOV170002_01_640/cc_2018DOV170002_01_640_PSC.jpg",
    "https://media.onthemarket.com/properties/6191869/797156548/composite.jpg",
    "https://media.onthemarket.com/properties/6191840/797152761/composite.jpg",
  ];
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: GridView(
        physics: BouncingScrollPhysics(), // if you want IOS bouncing effect, otherwise remove this line
        gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 2),//change the number as you want
        children: images.map((url) {
          return Card(child: Image.network(url));
        }).toList(),
      ),
    );
  }
}

如果您希望GridView项根据内容是动态的，则可以执行几行代码，但这是使用StaggeredGridView包的最简单方法。我在这里提供了示例答案。

以下是一个示例GridView.count：

import 'package:flutter/material.dart';

void main() => runApp(
      MaterialApp(
        home: ExampleGrid(),
      ),
    );

class ExampleGrid extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: GridView.count(
        crossAxisCount: 4,
        children: List.generate(40, (index) {
          return Card(
            child: Image.network("https://robohash.org/$index"),
          ); //robohash.org api provide you different images for any number you are giving
        }),
      ),
    );
  }
}

以上代码段的屏幕截图：

的示例SliverGridView：

import 'package:flutter/material.dart';

void main() => runApp(
      MaterialApp(
        home: ExampleGrid(),
      ),
    );

class ExampleGrid extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: CustomScrollView(
        primary: false,
        slivers: <Widget>[
          SliverPadding(
            padding: const EdgeInsets.all(20.0),
            sliver: SliverGrid.count(
              crossAxisSpacing: 10.0,
              crossAxisCount: 2,
              children: List.generate(20, (index) {
                return Card(child: Image.network("https://robohash.org/$index"));
              }),
            ),
          ),
        ],
      )
    );
  }
}