HarmonyOS 鸿蒙Next：如何将拍照或者相册的图片压缩并转化为base64格式

拉起相机拍照保存到指定的目录，然后转为base64的整个流程

import picker from '@ohos.multimedia.cameraPicker'
import camera from '@ohos.multimedia.camera';
import common from '@ohos.app.ability.common';
import { BusinessError } from '@ohos.base';
import fileuri from '@ohos.file.fileuri';
import fs from '@ohos.file.fs';
import { buffer } from '@kit.ArkTS';
import { image } from '@kit.ImageKit';

let mContext = getContext(this) as common.Context;
class CameraPosition {
  cameraPosition : camera.CameraPosition
  saveUri :string
  constructor(cameraPosition : camera.CameraPosition,saveUri:string) {
    this.cameraPosition = cameraPosition
    this.saveUri = saveUri
  }
}
let pathDir = getContext().filesDir;
let filePath = pathDir + `/${new Date().getTime()}.jpg`
fs.createRandomAccessFileSync(filePath, fs.OpenMode.CREATE);
let uri = fileuri.getUriFromPath(filePath);
async function demo() {
  try {
    let pickerProfile = new CameraPosition(camera.CameraPosition.CAMERA_POSITION_BACK,uri)
    //前置摄像机传CAMERA_POSITION_FRONT，后置摄像机传CAMERA_POSITION_BACK，saveuri传想存到对应沙箱的uri
    let pickerResult: picker.PickerResult = await picker.pick(mContext, [picker.PickerMediaType.PHOTO, picker.PickerMediaType.VIDEO], pickerProfile);
    console.log("the pick pickerResult is:" + JSON.stringify(pickerResult));
  } catch (error) {
    let err = error as BusinessError;
    console.error(`the pick call failed. error code: ${err.code}`);
  }
}

@Entry
@Component struct Photopage{
  @State base64Str:string = ''

async getImageBase64WithUri(uri:string): Promise<string> {
    const file = await fs.open(uri, fs.OpenMode.READ_ONLY);
    const imageSource : image.ImageSource = image.createImageSource(file.fd);
    const imagePackerApi = image.createImagePacker();
    // 设置打包参数
    // format：当前仅支持打包为JPEG、WebP 和 png 格式
    // quality：JPEG 编码输出图片质量
    // bufferSize：图片大小，默认 10M
    const packOpts: image.PackingOption = { format: "image/jpeg", quality: 100 };
    let imageBuffer: ArrayBuffer = new ArrayBuffer(1);
    let resultBase64Str = ''
    try {
      // 图片压缩或重新打包
      imageBuffer = await imagePackerApi.packing(imageSource, packOpts);
      let base64Str = buffer.from(imageBuffer).toString('base64')
      resultBase64Str="data:image/jpeg;base64,"+base64Str

    } catch (err) {
      console.error(`Invoke getImageArrayBufferWithUri failed, err: ${JSON.stringify(err)}`);
    }
    return resultBase64Str;
  }

  build(){
    Row(){
      Column(){
        Button('拉起后置摄像头').margin({bottom:20}).onClick(() =>{ demo() })
        Button('uri转为base64').onClick(async () =>{
          this.base64Str = await this.getImageBase64WithUri(uri)
        })
        Image(this.base64Str)
          .width(300)
          .height(400)
      }
    }

  }
}