怎么把PixelMap图片转BASE64

ImagePacker imagePacker = ImagePacker.create();
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
ImagePacker.PackingOptions packingOptions = new ImagePacker.PackingOptions();
imagePacker.initializePacking(byteArrayOutputStream, packingOptions);
imagePacker.addImage(pixelMap);
imagePacker.finalizePacking();
byte[] bytes = byteArrayOutputStream.toByteArray();
String base64String = Base64.getEncoder().encodeToString(bytes);