flutter开发实战-实现首页分类目录入口切换功能-Toy模板网

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。

在开发中经常遇到首页的分类入口，如美团的美食团购、打车等入口，左右切换还可以分页更多展示。

一、使用flutter_swiper_null_safety

在pubspec.yaml引入

  # 轮播图
  flutter_swiper_null_safety: ^1.0.2

二、实现swiper分页代码

由于我这里按照一页8条展示，两行四列展示格式。

当列表list传入的控件时候，一共的页数为

int getSwiperPageNumber() {
    int allLength = widget.list.length;
    int aPageNum = getSwiperOnePageNumber();
    if (allLength % aPageNum == 0) {
      return (allLength / aPageNum).toInt();
    }

    return (allLength / aPageNum).toInt() + 1;
  }

通过列表，一页数量计算每一页应该展示多少个按钮。

List getSwiperPagerItems(int pagerIndex) {
    List pagerItems = [];
    int allLength = widget.list.length;
    int aPageNum = getSwiperOnePageNumber();
    int start = pagerIndex * aPageNum;
    int end = (pagerIndex + 1) * aPageNum;
    if (end > allLength) {
      end = allLength;
    }
    pagerItems = widget.list.sublist(start, end);

    return pagerItems;
  }

一共pages的列表

int pagerNumber = getSwiperPageNumber();
    for (int index = 0; index < pagerNumber; index++) {
      CategorySwiperPagerItem swiperPagerItem = CategorySwiperPagerItem();
      swiperPagerItem.pagerIndex = index;
      swiperPagerItem.pagerItems = getSwiperPagerItems(index);
      swiperPagers.add(swiperPagerItem);
    }

通过使用flutter_swiper_null_safety来显示

Swiper(
        // 横向
        scrollDirection: Axis.horizontal,
        // 布局构建
        itemBuilder: (BuildContext context, int index) {
          CategorySwiperPagerItem swiperPagerItem = swiperPagers[index];
          return HomeCategoryPager(
            pagerIndex: swiperPagerItem.pagerIndex,
            pageItems: swiperPagerItem.pagerItems,
            width: itemWidth,
            height: itemHeight,
            containerHeight: showHeight,
            containerWidth: width,
          );
        },
        //条目个数
        itemCount: swiperPagers.length,
        // 自动翻页
        autoplay: false,
        // pagination: _buildSwiperPagination(),
        // pagination: _buildNumSwiperPagination(),
        //点击事件
        // onTap: (index) {
        //   LoggerManager().debug(" 点击 " + index.toString());
        // },
        // 相邻子条目视窗比例
        viewportFraction: 1,
        // 用户进行操作时停止自动翻页
        autoplayDisableOnInteraction: true,
        // 无限轮播
        loop: false,
        //当前条目的缩放比例
        scale: 1,
      ),

实现比较简单，

完整代码如下

import 'package:flutter/material.dart';
import 'package:flutter_screenutil/flutter_screenutil.dart';
import 'package:flutter_swiper_null_safety/flutter_swiper_null_safety.dart';
import 'package:flutter_app_dfaceintl/config/resource_manager.dart';
import 'package:flutter_app_dfaceintl/utils/color_util.dart';
import 'package:flutter_app_dfaceintl/widget/common/show_gesture_container.dart';
import 'package:one_context/one_context.dart';
import 'package:flutter_app_dfaceintl/config/logger_manager.dart';

class CategorySwiperPagerItem {
  int pagerIndex = 0;
  List pagerItems = [];
}

class HomeCategoryWidget extends StatefulWidget {
  const HomeCategoryWidget({
    Key? key,
    required this.rowNumber,
    required this.numberOfPerRow,
    required this.list,
    required this.screenWidth,
  }) : super(key: key);

  // 多少行
  final int rowNumber;

  // 一行几个
  final int numberOfPerRow;

  final List list;

  final double screenWidth;

  @override
  State<HomeCategoryWidget> createState() => _HomeCategoryWidgetState();
}

class _HomeCategoryWidgetState extends State<HomeCategoryWidget> {
  double showHeight = 0.0;
  double containVPadding = 5.0;
  double containHPadding = 10.0;

  List<CategorySwiperPagerItem> swiperPagers = [];

  bool showPagination = false;

  @override
  void initState() {
    // TODO: implement initState

    double containerHeight = getContainerMaxHeight(widget.screenWidth);
    showHeight = containerHeight + 2 * containVPadding;

    int pagerNumber = getSwiperPageNumber();
    for (int index = 0; index < pagerNumber; index++) {
      CategorySwiperPagerItem swiperPagerItem = CategorySwiperPagerItem();
      swiperPagerItem.pagerIndex = index;
      swiperPagerItem.pagerItems = getSwiperPagerItems(index);
      swiperPagers.add(swiperPagerItem);
    }

    if (swiperPagers.length > 1) {
      showPagination = true;
    }

    super.initState();
  }

  @override
  void dispose() {
    // TODO: implement dispose
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    double width = widget.screenWidth;
    double itemWidth = (width - 2 * containHPadding) / widget.numberOfPerRow;
    double itemHeight = itemWidth;
    return Container(
      width: width,
      height: showHeight,
      margin: EdgeInsets.symmetric(vertical: 5.0),
      padding: EdgeInsets.symmetric(
        vertical: containVPadding,
        horizontal: containHPadding,
      ),
      color: Colors.white,
      child: Swiper(
        // 横向
        scrollDirection: Axis.horizontal,
        // 布局构建
        itemBuilder: (BuildContext context, int index) {
          CategorySwiperPagerItem swiperPagerItem = swiperPagers[index];
          return HomeCategoryPager(
            pagerIndex: swiperPagerItem.pagerIndex,
            pageItems: swiperPagerItem.pagerItems,
            width: itemWidth,
            height: itemHeight,
            containerHeight: showHeight,
            containerWidth: width,
          );
        },
        //条目个数
        itemCount: swiperPagers.length,
        // 自动翻页
        autoplay: false,
        // pagination: _buildSwiperPagination(),
        // pagination: _buildNumSwiperPagination(),
        //点击事件
        // onTap: (index) {
        //   LoggerManager().debug(" 点击 " + index.toString());
        // },
        // 相邻子条目视窗比例
        viewportFraction: 1,
        // 用户进行操作时停止自动翻页
        autoplayDisableOnInteraction: true,
        // 无限轮播
        loop: false,
        //当前条目的缩放比例
        scale: 1,
      ),
    );
  }

  int getSwiperOnePageNumber() {
    return widget.numberOfPerRow * widget.rowNumber;
  }

  int getSwiperPageNumber() {
    int allLength = widget.list.length;
    int aPageNum = getSwiperOnePageNumber();
    if (allLength % aPageNum == 0) {
      return (allLength / aPageNum).toInt();
    }

    return (allLength / aPageNum).toInt() + 1;
  }

  List getSwiperPagerItems(int pagerIndex) {
    List pagerItems = [];
    int allLength = widget.list.length;
    int aPageNum = getSwiperOnePageNumber();
    int start = pagerIndex * aPageNum;
    int end = (pagerIndex + 1) * aPageNum;
    if (end > allLength) {
      end = allLength;
    }
    pagerItems = widget.list.sublist(start, end);

    return pagerItems;
  }

  double getContainerMaxHeight(double screenWidth) {
    double width = screenWidth;
    double itemSize = (width - 2 * containHPadding) / widget.numberOfPerRow;
    double maxHeight = itemSize * widget.rowNumber;

    int allLength = widget.list.length;
    if (allLength <= widget.numberOfPerRow) {
      maxHeight = itemSize;
    }

    return maxHeight;
  }
}

class HomeCategoryPager extends StatelessWidget {
  const HomeCategoryPager({
    Key? key,
    required this.pagerIndex,
    required this.pageItems,
    required this.width,
    required this.height,
    this.containerWidth,
    this.containerHeight,
  }) : super(key: key);

  final int pagerIndex;

  final List pageItems;

  final double width;
  final double height;

  final double? containerWidth;
  final double? containerHeight;

  @override
  Widget build(BuildContext context) {
    return Container(
      width: containerWidth,
      height: containerHeight,
      child: Wrap(
        children: pageItems
            .map((e) => HomeCategoryItem(
                  width: width,
                  height: height,
                ))
            .toList(),
      ),
    );
  }
}

class HomeCategoryItem extends StatelessWidget {
  const HomeCategoryItem({
    Key? key,
    required this.width,
    required this.height,
  }) : super(key: key);

  final double width;
  final double height;

  @override
  Widget build(BuildContext context) {
    return ShowGestureContainer(
      padding: EdgeInsets.symmetric(vertical: 5.0, horizontal: 5.0),
      width: width,
      height: height,
      highlightedColor: ColorUtil.hexColor(0xf0f0f0),
      onPressed: () {
        LoggerManager().debug("ShowGestureContainer");
      },
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        crossAxisAlignment: CrossAxisAlignment.center,
        children: [
          buildIcon(),
          Padding(
            padding: EdgeInsets.only(top: 5.0),
            child: buildTitle(),
          ),
        ],
      ),
    );
  }

  Widget buildTitle() {
    return Text(
      "栏目",
      textAlign: TextAlign.left,
      maxLines: 2,
      overflow: TextOverflow.ellipsis,
      softWrap: true,
      style: TextStyle(
        fontSize: 12,
        fontWeight: FontWeight.w500,
        fontStyle: FontStyle.normal,
        color: ColorUtil.hexColor(0x444444),
        decoration: TextDecoration.none,
      ),
    );
  }

  Widget buildIcon() {
    return Icon(
      Icons.access_alarm,
      size: 32.0,
      color: Colors.brown,
    );
  }
}