Flutter（四）：SingleChildScrollView、GridView

SingleChildScrollView、GridView 遇到的问题

以下代码会报错:

class GridViewPage extends StatefulWidget {const GridViewPage({super.key});@overrideState<GridViewPage> createState() => _GridViewPage();
}class _GridViewPage extends State<GridViewPage> {@overrideWidget build(BuildContext context) {return Scaffold(appBar: AppBar(title: const Text('GridView 布局')),body: SingleChildScrollView(child: GridView.count(crossAxisCount: 1,children: [Container(color: Colors.red),Container(color: Colors.green),Container(color: Colors.blue),Container(color: Colors.black),Container(color: Colors.grey),],),),);}
}

修改方案一

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存在问题：给定一个高度的方法虽然能解决报错问题，但是滚动区域会固定在所给高度内，无法自适应高度

class GridViewPage extends StatefulWidget {const GridViewPage({super.key});@overrideState<GridViewPage> createState() => _GridViewPage();
}class _GridViewPage extends State<GridViewPage> {@overrideWidget build(BuildContext context) {return Scaffold(appBar: AppBar(title: const Text('GridView 布局')),body: SizedBox(height: 500,child: GridView.count(crossAxisCount: 1,children: [Container(color: Colors.red),Container(color: Colors.green),Container(color: Colors.blue),Container(color: Colors.black),Container(color: Colors.grey),],),),);}
}

修改方案二

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存在问题：页面不能滚动

shrinkWrap: true: 自适应GridView高度

class GridViewPage extends StatefulWidget {const GridViewPage({super.key});@overrideState<GridViewPage> createState() => _GridViewPage();
}class _GridViewPage extends State<GridViewPage> {@overrideWidget build(BuildContext context) {return Scaffold(appBar: AppBar(title: const Text('GridView 布局')),body: SingleChildScrollView(child: GridView.count(crossAxisCount: 1,shrinkWrap: true,children: [Container(color: Colors.red),Container(color: Colors.green),Container(color: Colors.blue),Container(color: Colors.black),Container(color: Colors.grey),],),),);}
}

解决页面不能滚动问题

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physics: const NeverScrollableScrollPhysics(): 禁用GridView自带的滚动

class GridViewPage extends StatefulWidget {const GridViewPage({super.key});@overrideState<GridViewPage> createState() => _GridViewPage();
}class _GridViewPage extends State<GridViewPage> {@overrideWidget build(BuildContext context) {return Scaffold(appBar: AppBar(title: const Text('GridView 布局')),body: SingleChildScrollView(child: GridView.count(crossAxisCount: 1,shrinkWrap: true,physics: const NeverScrollableScrollPhysics(),children: [Container(color: Colors.red),Container(color: Colors.green),Container(color: Colors.blue),Container(color: Colors.black),Container(color: Colors.grey),],),),);}
}

实现 GridView 布局

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属性	描述
shrinkWrap	自适应宽高
scrollDirection	布局方向
childAspectRatio	主轴、交叉轴比
mainAxisSpacing	主轴间距
crossAxisSpacing	交叉轴间距
crossAxisCount	交叉轴列数
maxCrossAxisExtent	交叉轴列最尺寸

import 'package:flutter/material.dart';class TitleWidget extends StatelessWidget {final String title;const TitleWidget(this.title, {super.key});@overrideWidget build(BuildContext context) {return Container(margin: const EdgeInsets.fromLTRB(10, 5, 10, 5),padding: const EdgeInsets.only(left: 5),decoration: const BoxDecoration(border: Border(left: BorderSide(color: Colors.lightBlue, width: 5)),),child: Text(title),);}
}class ContainerWidget extends StatelessWidget {final Color color;final String title;const ContainerWidget({super.key, required this.color, required this.title});@overrideWidget build(BuildContext context) {return Container(decoration: BoxDecoration(color: color,borderRadius: const BorderRadius.all(Radius.circular(5)),),child: Center(child: Text(title)),);}
}class GridViewPage extends StatefulWidget {const GridViewPage({super.key});@overrideState<GridViewPage> createState() => _GridViewPage();
}class _GridViewPage extends State<GridViewPage> {List<ContainerWidget> containerWidgetList = const [ContainerWidget(color: Colors.red, title: 'RED'),ContainerWidget(color: Colors.orange, title: 'ORANGE'),ContainerWidget(color: Colors.yellow, title: 'YELLOW'),ContainerWidget(color: Colors.green, title: 'GREEN'),ContainerWidget(color: Colors.cyan, title: 'CYAN'),ContainerWidget(color: Colors.blue, title: 'BLUE'),ContainerWidget(color: Colors.purple, title: 'PURPLE'),ContainerWidget(color: Colors.grey, title: 'GREY'),];@overrideWidget build(BuildContext context) {return Scaffold(appBar: AppBar(title: const Text('GridView 布局')),body: SingleChildScrollView(child: Column(crossAxisAlignment: CrossAxisAlignment.start,children: [const TitleWidget('GridView.count'),SizedBox(height: 160,child: GridView.count(scrollDirection: Axis.horizontal,crossAxisCount: 1,padding: const EdgeInsets.only(left: 10, right: 10),crossAxisSpacing: 0,mainAxisSpacing: 10,childAspectRatio: 0.6,children: containerWidgetList,),),const TitleWidget('GridView.extent'),GridView.extent(shrinkWrap: true,physics: const NeverScrollableScrollPhysics(),scrollDirection: Axis.vertical,maxCrossAxisExtent: 200,childAspectRatio: 0.8,padding: const EdgeInsets.only(left: 10, right: 10),mainAxisSpacing: 10,crossAxisSpacing: 10,children: containerWidgetList,),const TitleWidget('SliverGridDelegateWithFixedCrossAxisCount'),SizedBox(height: 330,child: GridView(gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 2,crossAxisSpacing: 10,mainAxisSpacing: 10,childAspectRatio: 0.6,),scrollDirection: Axis.horizontal,padding: const EdgeInsets.only(left: 10, right: 10),children: containerWidgetList,),),const TitleWidget('SliverGridDelegateWithMaxCrossAxisExtent'),GridView(gridDelegate: const SliverGridDelegateWithMaxCrossAxisExtent(maxCrossAxisExtent: 200,childAspectRatio: 2,mainAxisSpacing: 10,crossAxisSpacing: 10,),shrinkWrap: true,physics: const NeverScrollableScrollPhysics(),scrollDirection: Axis.vertical,padding: const EdgeInsets.only(left: 10, right: 10, bottom: 10),children: containerWidgetList,),],),),);}
}