HarmonyOS pixelMap怎么转base64

PixelMap转base64：PixelMap转换成base64必须先使用imagePacker将pixelMap压缩后再进行base64，若要实现无损压缩，将PixelMap压缩成PNG，即调用imagePacker时，let packOpts: image.PackingOption = { format: ‘image/png’, quality: 100 };

参考如下代码：

let resourceManager = getContext(this).resourceManager
let imageArray = await resourceManager.getMediaContent($r('app.media.beer'));
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/png', 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);
})