RN端HarmonyOS的react-native-image-picker，获取图片只能获取uri，无法获取base64

import { image } from '@kit.ImageKit'; 
import { buffer } from '@kit.ArkTS'; 
 
@Entry 
@Component 
struct Index { 
  @State message: string = 'PixelMapToBase64'; 
  @State base64: string = ''; 
  build() { 
    Row() { 
      Column() { 
        Text(this.message) 
          .fontSize(50) 
          .fontWeight(FontWeight.Bold) 
          .onClick(async () => { 
            let resourceManager = getContext(this).resourceManager 
            let imageArray = await resourceManager.getMediaContent($r('app.media.sample7')); 
            let pixelBuffer = new Uint8Array(imageArray).buffer as Object as ArrayBuffer; 
            let imageResource = image.createImageSource(pixelBuffer); 
            let opts: image.DecodingOptions = { editable: true } 
            let pixelMap = await imageResource.createPixelMap(opts); 
            // 转换成base64 
            const imagePackerApi: image.ImagePacker = image.createImagePacker(); 
            let packOpts: image.PackingOption = { format: 'image/jpeg', quality: 100 }; 
            imagePackerApi.packing(pixelMap, packOpts).then((data: ArrayBuffer) => { 
              let buf: buffer.Buffer = buffer.from(data); 
              this.base64 = 'data:image/jpeg;base64,' + buf.toString('base64', 0, buf.length); 
              console.info('base64: ' + this.base64); 
            }) 
          }) 
        Image(this.base64) 
          .width(200).height(200).margin(15) 
      } 
      .width('100%') 
    } 
    .height('100%') 
 
  } 
}