7、Flutter banner_view 轮播图的使用

1、前言

实现轮播图，效果如下：

2、实现

将采用 banner_view 实现：资源库地址

2.1、yaml 引入依赖

在 pubspec.yaml 声明需要引用的库，执行命令 flutter packages get 进行拉取即可使用。

banner_view: "^1.1.2"

2.2、代码中引入依赖

 在资源库地址下方，作者提供了 banner_view 的几种展示方式。

import 'package:flutter/material.dart';
import 'package:banner_view/banner_view.dart';

import 'Pair.dart';
import 'factory/BannerItemFactory.dart';

class BannerViewPage extends StatefulWidget {
  @override
  _BannerViewPageState createState() => new _BannerViewPageState();
}

class _BannerViewPageState extends State<BannerViewPage> {

  @override
  Widget build(BuildContext context) {

    return new Scaffold(
      body:
          new Container(
            child:  new Column(
              children: <Widget>[
                new Container(
                  alignment: Alignment.center,
                  height: 200.0,
                  child: this._bannerView0(),
                  padding: EdgeInsets.only(bottom: 10.0),
                )
              ],
            ),
          ),
      );
  }

  /**
   * 第一种方式
   */
  BannerView _bannerView0() {

    // 盛放图片的 List
    List<Pair<String, Color>> param = [
      Pair.create('https://p5.ssl.qhimg.com/dm/456_209_/t01f43c5849ef5f521a.jpg', Colors.red[500]),
      Pair.create('https://p.ssl.qhimg.com/t0171bb61911ebe8899.jpg', Colors.green[500]),
      Pair.create('https://p.ssl.qhimg.com/t01ee77978d3a95a3ae.jpg', Colors.blue[500]),
    ];

    return new BannerView(
      BannerItemFactory.banners(param),
    );
//    return new BannerView(
//      BannerItemFactory.banners(param),
//      indicatorMargin: 10.0,
//      indicatorNormal: new Container(
//         5.0,
//        height: 5.0,
//        decoration: new BoxDecoration(
//          color: Colors.green,
//          shape: BoxShape.rectangle,
//        ),
//      ),
//      indicatorSelected: new Container(
//         15.0,
//        height: 5.0,
//        decoration: new BoxDecoration(
//          color: Colors.black,
//          shape: BoxShape.rectangle,
//          borderRadius: new BorderRadius.all(
//            new Radius.circular(5.0),
//          ),
//        ),
//      ),
//      indicatorBuilder: (context, indicator) {
//        Widget cc = new Container(
//          padding: new EdgeInsets.symmetric(horizontal: 20.0,),
//          height: 44.0,
//           double.infinity,
//          color: Colors.grey[300],
//          child: indicator,
//        );
//        return new Opacity(
//          opacity: 0.5,
//          child: cc,
//        );
//      },
//    );
  }

  /**
   * 第二种方式
   */
  BannerView _bannerView() {

    var pre = 'https://raw.githubusercontent.com/yangxiaoweihn/Assets/master';
    List<Pair<String, Color>> param = [
      Pair.create('https://raw.githubusercontent.com/yangxiaoweihn/Assets/master/cars/car_0.jpg', Colors.red[100]),
      Pair.create('https://raw.githubusercontent.com/yangxiaoweihn/Assets/master/cartoons/ct_0.jpg', Colors.green[100]),
      Pair.create('https://raw.githubusercontent.com/yangxiaoweihn/Assets/master/pets/cat_1.jpg', Colors.blue[100]),
      Pair.create('https://raw.githubusercontent.com/yangxiaoweihn/Assets/master/scenery/s_1.jpg', Colors.yellow[100]),
      Pair.create('https://raw.githubusercontent.com/yangxiaoweihn/Assets/master/cartoons/ct_1.jpg', Colors.red[100]),
//      Pair.create('$pre/cartoons/ct_1.jpg', Colors.red[100]),
    ];

    return new BannerView(
      BannerItemFactory.banners(param),
      indicatorMargin: 10.0,
      indicatorNormal: new Container(
         5.0,
        height: 5.0,
        decoration: new BoxDecoration(
          color: Colors.green,
          shape: BoxShape.rectangle,
        ),
      ),
      indicatorSelected: new Container(
         15.0,
        height: 5.0,
        decoration: new BoxDecoration(
          color: Colors.black,
          shape: BoxShape.rectangle,
          borderRadius: new BorderRadius.all(
            new Radius.circular(5.0),
          ),
        ),
      ),
      indicatorBuilder: (context, indicator) {
        Widget cc = new Container(
          padding: new EdgeInsets.symmetric(horizontal: 20.0,),
          height: 44.0,
           double.infinity,
          color: Colors.grey[300],
          child: indicator,
        );
        return new Opacity(
          opacity: 0.5,
          child: cc,
        );
      },
    );
  }
}