import 'package:flutter/material.dart';

/// create by 张风捷特烈 on 2020-03-27
/// contact me by email 1981462002@qq.com
/// 说明:

//    {
//      "widgetId": 163,
//      "name": 'GridView.builder构造',
//      "priority": 4,
//      "subtitle":
//          "【itemCount】 : 条目数量   【int】\n"
//          "【gridDelegate】 : 网格代理   【SliverGridDelegate】\n"
//          "【itemBuilder】 : 条目构造器  【IndexedWidgetBuilder】",
//    }
class BuilderGridView extends StatelessWidget {
  final data = List.generate(128, (i) => Color(0xFF33FFF - 2*i));

  @override
  Widget build(BuildContext context) {
    return Container(
      height: 200,
      child: GridView.builder(
          itemCount: data.length,
          scrollDirection: Axis.vertical,
          gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(//网格代理：定交叉轴数目
              crossAxisCount: 4,//条目个数
              mainAxisSpacing: 5,//主轴间距
              crossAxisSpacing: 5,//交叉轴间距
              childAspectRatio:1/0.618),
          itemBuilder: (_, int position)=> _buildItem(data[position])
      ),
    );
  }

  Container _buildItem(Color color) => Container(
    alignment: Alignment.center,
    width: 100,
    height: 30,
    color: color,
    child: Text(
      colorString(color),
      style: TextStyle(color: Colors.white, shadows: [
        Shadow(
            color: Colors.black,
            offset: Offset(.5, .5),
            blurRadius: 2)
      ]),
    ),
  );

  String colorString(Color color) =>
      "#${color.value.toRadixString(16).padLeft(8, '0').toUpperCase()}";
}