如何在 Flutter 中创建 GridView 布局

Question

我正在尝试在 flutter 中布置一个 4x4 的瓷砖网格。我设法用列和行来做到这一点。但是现在我找到了 GridView 组件。谁能举例说明如何使用它？

我无法真正理解文档。我似乎没有得到我想要的结果。

Answer 1

GridView is used for implementing material grid lists。如果您知道您有固定数量的项目并且数量不是很多（16 个就可以），您可以使用 GridView.count。但是，您应该注意 GridView 是可滚动的，如果这不是您想要的，您最好只使用行和列。

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示例，可以在 here.

中找到

Answer 3

请访问此repo。

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(),
    );
  }

下面的截图包含 crossAxisCount: 2

Answer 4

GridView针对不同场景的命名构造函数很少，

构造函数

GridView
GridView.builder
GridView.count
GridView.custom
GridView.extent

下面是GridView构造函数的例子：

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(),
      ),
    );
  }
}

如果您希望您的 GridView 项目根据内容动态变化，您可以用几行代码来做到这一点，但最简单的方法是使用 StaggeredGridView 包。我已经用示例 .

提供了答案

下面是一个 GridView.count:

的例子

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：

SliverGridView 的示例：

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"));
              }),
            ),
          ),
        ],
      )
    );
  }
}

Answer 5

根据您的需要使用任何一个。

GridView.count(...)

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

GridView.builder(...)

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

GridView(...)

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

GridView.custom(...)

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

GridView.extent(...)

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

输出（全部相同）：

Answer 6

您可以使用 flutter_layout_grid 包

首先，我们需要将其添加到our pubspec.yaml:

dependencies:
  flutter_layout_grid: ^1.0.3

然后，我们可以定义一个自定义 ItemCardLayoutGrid 小部件来显示 LayoutGrid 小部件中的每个 ItemCard：

import 'package:flutter_layout_grid/flutter_layout_grid.dart';

class ItemCardLayoutGrid extends StatelessWidget {
  const ItemCardLayoutGrid({
    Key? key,
    required this.crossAxisCount,
    required this.items,
  })  
  // we only plan to use this with 1 or 2 columns
  : assert(crossAxisCount == 1 || crossAxisCount == 2),
    // assume we pass an list of 4 items for simplicity
    assert(items.length == 4),
    super(key: key);
  final int crossAxisCount;
  final List<ItemCardData> items;

  @override
  Widget build(BuildContext context) {
    return LayoutGrid(
      // set some flexible track sizes based on the crossAxisCount
      columnSizes: crossAxisCount == 2 ? [1.fr, 1.fr] : [1.fr],
      // set all the row sizes to auto (self-sizing height)
      rowSizes: crossAxisCount == 2
          ? const [auto, auto]
          : const [auto, auto, auto, auto],
      rowGap: 40, // equivalent to mainAxisSpacing
      columnGap: 24, // equivalent to crossAxisSpacing
      // note: there's no childAspectRatio
      children: [
        // render all the cards with *automatic child placement*
        for (var i = 0; i < items.length; i++)
          ItemCard(data: items[i]),
      ],
    );
  }
}

并在循环中传递子项列表（我们的 ItemCard 小部件）：

children: [
  // render all the cards with *automatic child placement*
  for (var i = 0; i < items.length; i++)
    ItemCard(data: items[i]),
]

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