#鸿蒙学习大百科#如何获取图片的缩略图？

import { common, Want, wantConstant } from '@kit.AbilityKit';
import { photoAccessHelper } from '@kit.MediaLibraryKit';
import { dataSharePredicates } from '@kit.ArkData';
// 定义一个uri数组，用于接收PhotoViewPicker选择图片返回的uri
let uris: Array<string> = [];
const context = getContext(this);
async function uriGetAssets() {
  try {
    let phAccessHelper = photoAccessHelper.getPhotoAccessHelper(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', uris[0]);
    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(photoAccessHelper.PhotoKeys.WIDTH));
    console.info('asset height: ', asset.get(photoAccessHelper.PhotoKeys.HEIGHT));
    console.info('asset title: ' + asset.get(photoAccessHelper.PhotoKeys.TITLE));
    // 获取缩略图
    asset.getThumbnail((err, pixelMap) => {
      if (err == undefined) {
        console.info('getThumbnail successful ' + JSON.stringify(pixelMap));
      } else {
        console.error('getThumbnail fail', err);
      }
    });
  } catch (error) {
    console.error('uriGetAssets failed with err: ' + JSON.stringify(error));
  }
}