Modify Image fit property on custom widget class

I have my own custom Image widget, I want to modify input image's property inside my class. I don't know how to initialize a new Image object with custom fit, width etc.

class MyImage extends StatelessWidget {
  Image myImage;
  final BoxFit fit;

  MyImage.image(Image image,{ = BoxFit.cover})
  : assert(image != null){ = fit; // there is error says that it's final prop
    image.alignment = Alignment(1,0);// same error
    myImage = image;

  Widget build(BuildContext context) {
    return myImage;

class Home extends StatefulWidget{
  _HomeState createState() => _HomeState();

class _HomeState extends State<Home> {
  Image image ;
  void initState(){
    image ="", fit: BoxFit.contain);
  Widget build(BuildContext context){
    return Material(
      child: Column(