flutter GridView和Wrap

GridView有2种gridDelegate；

• [记录小嵌套冲突的问题，SingleChildScrollView，ListView,GrilView嵌套问题解决，子布局添加属性]

  physics: NeverScrollableScrollPhysics(),
  shrinkWrap: true,

---

1. SliverGridDelegateWithMaxCrossAxisExtent：
   没有固定行数，这种类似于wrap,可以自动换行，布局适配性较好

 return GridView.builder(
     // physics: NeverScrollableScrollPhysics(),
      //shrinkWrap: true,
      padding: const EdgeInsets.all(0.0),
      gridDelegate: SliverGridDelegateWithMaxCrossAxisExtent(
        //单个widget的水平最大宽度
        maxCrossAxisExtent: 110,
        //垂直单个子widget间距
        mainAxisSpacing: 4,
        //水平单个子widget间距
        crossAxisSpacing: 4,
      ),
      itemBuilder: (context, index) {
          return Image.file(_imageFileList[index], fit: BoxFit.fill);
      },
      itemCount: _imageFileList.length,
    );

2. SliverGridDelegateWithFixedCrossAxisCount
   固定行数，这种相比第一种，固定了item宽高比，适配起来比较麻烦

  return GridView.builder(
      padding: const EdgeInsets.all(0.0),
      gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
          //横轴元素个数
          crossAxisCount: 3,
          //垂直单个子widget间距
          mainAxisSpacing: 4,
          //水平单个子widget间距
          crossAxisSpacing: 4,
          //item宽高比例
          childAspectRatio: 1.0),
      itemBuilder: (context, index) {
          return Image.file(_imageFileList[index], fit: BoxFit.fill);
      },
      itemCount: _imageFileList.length,
    );

3. wrap部分地方也是可代替GrildView来进行使用的，并且它的布局适配性也是很nice的，不过并不能替代，GridView可以根据index更好的去添加头部，尾部；在slivers下也使用不了，只能使用对应的SliverGrid，SliverList;使用上没什么好说的，一搜一大堆；

Wrap(
  spacing: 8.0, // gap between adjacent chips
  runSpacing: 4.0, // gap between lines
  children: [
    Chip(
      avatar: CircleAvatar(
          backgroundColor: Colors.blue.shade900, child: new Text('AH', style: TextStyle(fontSize: 10.0),)),
      label: Text('Hamilton'),
    ),
    Chip(
      avatar: CircleAvatar(
          backgroundColor: Colors.blue.shade900, child: new Text('ML', style: TextStyle(fontSize: 10.0),)),
      label: Text('Lafayette'),
    ),
    Chip(
      avatar: CircleAvatar(
          backgroundColor: Colors.blue.shade900, child: new Text('HM', style: TextStyle(fontSize: 10.0),)),
      label: Text('Mulligan'),
    ),
    Chip(
      avatar: CircleAvatar(
          backgroundColor: Colors.blue.shade900, child: new Text('JL', style: TextStyle(fontSize: 10.0),)),
      label: Text('Laurens'),
    ),
  ],
)