Flutter 转换函数上传文件上传Uint8List

我正在使用以下函数将文件从我的应用程序上传到服务器:

void _upload(File file) {

    if (file == null) return;
    setState(() {
      _textoInfo = "subiendofotoalservidor".tr();
    });

    String base64Image = base64Encode(file.readAsBytesSync());
    String fileName = file.path.split("/").last;

    http.post(Uri.parse(phpEndPoint), body: {
      "image": base64Image,
      "name": fileName,
    }).then((res) async {
      print("respuesta servidor ${res.body}");

      setState(() {
        _textoInfo = "fotoperfilactualizada".tr();
        miImagen = fileName;
      });


      print("foto subida ${miImagen}");

      _cambiarFotoAdmin(miImagen, widget.administrador.email, context);




    //  cambiarImagenUsuario(fileName);
    }).catchError((err) {

    });

    http.post(Uri.parse(phpEndPointFoto), body: {
      "foto":fileName,
      "id": miId,
    }).then((res) async {





    //  cambiarImagenUsuario(fileName);
    Provider.of<UsuarioProvider>(context, listen: false).cambiarImagenAdministrador(fileName);
    }).catchError((err) {

    });


  }

现在，在我的新应用程序中，我在Web浏览器上执行Ffltter项目，IMAGE_PICKER不是从设备库中拾取图像，而是在计算机文件系统上拾取图像，拾取的图像来自类型Uin8List.

如何将Function_Upload(文件文件)改为_Upload(Uin8List文件)？

编辑

这里有用于 Select 图像的函数:

  Future<void> _openImagePickerGallery() async {

    if(!kIsWeb){
      final XFile? pickedImage =
      await _picker.pickImage(source: ImageSource.gallery);
      if (pickedImage != null) {
        setState(() {
          _image = File(pickedImage.path);
        });
      }
    }
    else if(kIsWeb){
      final XFile? pickedImage =
      await _picker.pickImage(source: ImageSource.gallery);
      if (pickedImage != null) {

        var f = await pickedImage.readAsBytes();
        
        
        setState(() {
          hayFoto = true;
          webImage = f;
        });

        //  _image = File(pickedImage.path);

      }
    }

  }