鸿蒙 ark ui 轮播图实现教程

前言：

各位同学有段时间没有见面因为一直很忙所以就没有去更新博客。最近有在学习这个鸿蒙的ark ui开发因为鸿蒙不是发布了一个鸿蒙next的测试版本明年会启动纯血鸿蒙应用所以我就想提前给大家写一些博客文章

效果图

具体实现

我们在鸿蒙的ark ui 里面列表使用我们的Swiper组件来实现我们的轮播图

准备数据源

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import { PictureItem } from '../bean/PictureItem';

/**
 * Pictures of banner.
 */
export const PICTURE_BANNER: PictureItem[] = [
  { 'id': '1', 'name': '怒海', 'description': '怒海波涛', 'image': $r('app.media.image1') },
  { 'id': '2', 'name': '大山深处', 'description': '大山深处感人的亲情之歌', 'image': $r('app.media.image2') },
  { 'id': '3', 'name': '荒漠', 'description': '荒漠的亲情之歌', 'image': $r('app.media.image3') }
];

/**
 * type of pictures.
 */
export enum PictureType {
  BANNER = 'banner',
}

Bean类

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/**
 * Picture entity class.
 */
export class PictureItem {
  id: string;
  name: string;
  description: string;
  image: Resource;

  constructor(id: string, name: string, description: string, image: Resource) {
    this.id = id;
    this.name = name;
    this.description = description;
    this.image = image;
  }
}

宽高常量配置

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/**
 * Common constants for all features.
 */
export class CommonConstants {

  /**
   * animation duration of tab content switching.
   */
  static readonly DURATION_ADS = 200;


  /**
   * height of carousel title.
   */
  static readonly HEIGHT_CAROUSEL_TITLE = 90;

  /**
   * fontSize of description.
   */
  static readonly FONT_SIZE_DESCRIPTION = 12;
  /**
   * font size of title.
   */
  static readonly FONT_SIZE_TITLE = 20;

  static readonly FONT_WEIGHT_LIGHT = 400;
  /**
   * bold font.
   */
  static readonly FONT_WEIGHT_BOLD = 700;

  /**
   * page layout weight.
   */
  static readonly LAYOUT_WEIGHT = 1;

  /**
   * border angle.
   */
  static readonly BORDER_RADIUS = 12;

  /**
   * line height for more.
   */
  static readonly LINE_HEIGHT_MORE = 19;
  /**
   * rolling duration.
   */
  static readonly SWIPER_TIME = 1500;
  /**
   * margin of text bottom.
   */
  static readonly BOTTOM_TEXT = 4;

  /**
   * margin of banner top.
   */
  static readonly TOP_ADS = 12;
  /**
   * margin of banner left.
   */
  static readonly ADS_LEFT = 12;

  /*
   * maximum width.
   */
  static readonly FULL_WIDTH = '100%';
  /**
   * maximum height.
   */
  static readonly FULL_HEIGHT = '100%';
  /**
   * width of tab page.
   */
  static readonly PAGE_WIDTH = '100%';
  /**
   * height of banner.
   */
  static readonly HEIGHT_BANNER = '27%';

 
}

具体布局

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import router from '@ohos.router';
import { PictureItem } from '../bean/PictureItem';
import { PictureType } from '../constants/PictureConstants';
import { initializePictures, startPlay, stopPlay } from './PictureViewModel';
import { CommonConstants } from '../constants/CommonConstant';



@Extend(Text) function textStyle(fontSize: number, fontWeight: number) {
  .fontSize(fontSize)
  .fontColor($r('app.color.start_window_background'))
  .fontWeight(fontWeight)
}

/**
 * Carousel banner.
 */
@Component
export struct Banner {
  @State index: number = 0;
  private imageArray: Array<PictureItem> = [];
  private swiperController: SwiperController = new SwiperController();

  aboutToAppear() {
    // Data Initialization.
    this.imageArray = initializePictures(PictureType.BANNER);
    // Turn on scheduled task.
    startPlay(this.swiperController);
  }

  aboutToDisappear() {
    stopPlay();
  }

  build() {
    Swiper(this.swiperController) {
      ForEach(this.imageArray, item => {
        Stack({ alignContent: Alignment.TopStart }) {
          Image(item.image)
            .objectFit(ImageFit.Fill)
            .height(CommonConstants.FULL_HEIGHT)
            .width(CommonConstants.FULL_WIDTH)
            .borderRadius(CommonConstants.BORDER_RADIUS)
            .align(Alignment.Center)
            .onClick(() => {
             console.log("点击事件 item"+item.id)
            })

          Column() {
            Text($r('app.string.movie_classic'))
              .textStyle(CommonConstants.FONT_SIZE_DESCRIPTION, CommonConstants.FONT_WEIGHT_LIGHT)
              .margin({ bottom: CommonConstants.BOTTOM_TEXT })
            Text(item.name)
              .textStyle(CommonConstants.FONT_SIZE_TITLE, CommonConstants.FONT_WEIGHT_BOLD)
          }
          .alignItems(HorizontalAlign.Start)
          .height(CommonConstants.HEIGHT_CAROUSEL_TITLE)
          .margin({ top: CommonConstants.TOP_ADS, left: CommonConstants.ADS_LEFT })
        }
        .height(CommonConstants.FULL_HEIGHT)
        .width(CommonConstants.FULL_WIDTH)
      }, item => JSON.stringify(item))
    }
    .width(CommonConstants.PAGE_WIDTH)
    .height(CommonConstants.HEIGHT_BANNER)
    .index(this.index)
    .indicatorStyle({ selectedColor: $r('app.color.start_window_background') })
    .indicator(true)
    .duration(CommonConstants.DURATION_ADS)
  }
}

使用 indicator 属性设置是否支持自动轮播

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.indicator(true)

设置自动轮播间隔时间

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.duration(CommonConstants.DURATION_ADS)

viewmodel 实现

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import { PictureItem } from '../bean/PictureItem';
import { PICTURE_BANNER} from '../constants/PictureConstants';
import { PictureType } from '../constants/PictureConstants';
import { CommonConstants } from '../constants/CommonConstant';

/**
 * Initialize picture data according to type.
 *
 * @param initType Init type.
 */
export function initializePictures(initType: string): Array<PictureItem> {
  let imageDataArray: Array<PictureItem> = [];
  switch (initType) {
    case PictureType.BANNER:
      PICTURE_BANNER.forEach((item) => {
        imageDataArray.push(new PictureItem(item.id, item.name, item.description, item.image));
      })
      break;
    default:
      break;
  }
  return imageDataArray;
}

let timerIds: number[] = [];

/**
 * start scheduled task.
 *
 * @param swiperController Controller.
 */
export function startPlay(swiperController: SwiperController) {
  let timerId = setInterval(() => {
    swiperController.showNext();
  }, CommonConstants.SWIPER_TIME);
  timerIds.push(timerId);
}

/**
 * stop scheduled task.
 */
export function stopPlay() {
  timerIds.forEach((item) => {
    clearTimeout(item);
  })
}