flutter網格式佈局GridView

網格式佈局，沒有什麼理解的地方都是記住就可以了

@override
Widget build(BuildContext context) {
  return new GridView.builder(
    gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
        crossAxisCount: 3,  //一行幾個
        mainAxisSpacing: 10.0,  //Y軸間距
        crossAxisSpacing: 7.0,   //X軸間距
        childAspectRatio: 0.7),
    itemCount: items.length,
    itemBuilder: (context, index) {
      return new GestureDetector(
        child: Image.network(items[index].url),
        onTap: () {
          Navigator.push(context, MaterialPageRoute(builder: (context) {
            return new PosterShow(
              group: this.items[index].imgGroup,
              store: 0,
            );
          }));
        },
      );
    },
  );
}