HarmonyOS鸿蒙Next中CameraKit录制视频之后获取其缩略图不能显示

可以试一下下面的代码，看看能否获取到相册缩略图，新建工程，无需权限申请：

import { common } from '@kit.AbilityKit';
import { picker } from '@kit.CoreFileKit';
import fs from '@ohos.file.fs';
import { photoAccessHelper } from '@kit.MediaLibraryKit';
import { dataSharePredicates } from '@kit.ArkData';
import { image } from '@kit.ImageKit';
import { media } from '@kit.MediaKit';

@Entry
@Component
struct Index {
  @State imagePath: string = ''
  @State pixelMap:image.PixelMap  | undefined = undefined
  private controller:VideoController | undefined
  private context = this.getContext(this) as common.UIAbilityContext;

  build() {
    Row() {
      Column() {
        Video({
          src:this.imagePath,
          controller: this.controller
        }).height(300).width('100%').margin({ bottom: 20 })
        Button("选择视频")
          .onClick(() => {
            this.selectPhoto()
          })
        Image(this.pixelMap).width(300).height(400)
      }.width('100%')
    }.height('100%')
  }

  selectPhoto() {
    const photoSelectOptions = new picker.PhotoSelectOptions();
    const photoViewPicker = new picker.PhotoViewPicker();
    photoSelectOptions.MIMEType = picker.PhotoViewMIMETypes.VIDEO_TYPE; // 过滤选择媒体文件类型为IMAGE
    photoSelectOptions.maxSelectNumber = 1; // 选择媒体文件的最大数目
    photoViewPicker.select(photoSelectOptions).then((photoSelectResult: picker.PhotoSelectResult) => {
      const fileUri = photoSelectResult.photoUris[0]

      //this.getFileInfo(fileUri)
      //this.uriGetAssets(fileUri)
      this.testFetchFrameByTime(fileUri)
    })
  }

  async getFileInfo(filePathString: string) {
    let resFile = fs.openSync(filePathString, fs.OpenMode.READ_ONLY)
    const dateStr = (new Date().getTime()).toString()
    // 临时文件目录
    let newPath = this.context.filesDir +'/' + dateStr + resFile.name;
    // 转化路径
    fs.copyFileSync(resFile.fd, newPath);
    // 新的路径
    let realUri = 'file://' + newPath;
    this.imagePath = realUri
    console.log(this.imagePath)
  }

  async  uriGetAssets(videoUri:string) {
    try {
      let phAccessHelper = photoAccessHelper.getPhotoAccessHelper(this.context);
      let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
      // 配置查询条件，使用PhotoViewPicker选择图片返回的uri进行查询
      predicates.equalTo('uri', videoUri);
      let fetchOption: photoAccessHelper.FetchOptions = {
        fetchColumns: [],
        predicates: predicates
      };
      let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await phAccessHelper.getAssets(fetchOption);
      // 得到uri对应的PhotoAsset对象，读取文件的部分信息
      const asset: photoAccessHelper.PhotoAsset = await fetchResult.getFirstObject();
      console.info('asset displayName: ', asset.displayName);
      console.info('asset uri: ', asset.uri);
      console.info('asset photoType: ', asset.photoType);
      console.info('asset width: ', asset.get('width'));

      // 获取缩略图
      asset.getThumbnail((err, pixelMap) => {
        if (err == undefined) {
          this.pixelMap = pixelMap
          console.info('getThumbnail successful ' + JSON.stringify(pixelMap));
        } else {
          console.error('getThumbnail fail', err.code + err.message);
        }
      });
    } catch (error){
      console.error('uriGetAssets failed with err: ' + JSON.stringify(error));
    }
  }

  async testFetchFrameByTime(fileUri:string) {
    // 创建AVImageGenerator对象
    try {
      let avImageGenerator: media.AVImageGenerator = await media.createAVImageGenerator()
      // 设置fdSrc
      let resFile = fs.openSync(fileUri, fs.OpenMode.READ_ONLY)
      let fileLength = fs.statSync(resFile.fd).size
      avImageGenerator.fdSrc = { fd: resFile.fd, offset: 0, length: fileLength }
      // 初始化入参
      let timeUs = 0
      let queryOption = media.AVImageQueryOptions.AV_IMAGE_QUERY_NEXT_SYNC
      let param: media.PixelMapParams = {
        width: 300,
        height: 300
      }
      // 获取缩略图（promise模式）
      let pixelMap = await avImageGenerator.fetchFrameByTime(timeUs, queryOption, param)
      this.pixelMap = pixelMap
      // 释放资源（promise模式）
      avImageGenerator.release()
      fs.closeSync(resFile.fd)
    } catch (e) {
      console.info(`testTag fetchFrameByTime catch exception: ${JSON.stringify(e)}`)
    }
  }
}