image fit flutter

FittedBox(
  child: Image.asset('foo.png'),
  fit: BoxFit.fill,
)

// If your container has a fixed height use the following code
Container(
  width: MediaQuery.of(context).size.width,
  height: 100,
  decoration: BoxDecoration(
    image: DecorationImage(
      fit: BoxFit.fill,
      image: NetworkImage("https://picsum.photos/250?image=9"),
    ),
  ),
)