Get size from widget flutter code example

Example 1: flutter get width of screen

double height = MediaQuery.of(context).size.height;
double width = MediaQuery.of(context).size.width;

Example 2: get position of a widget in screen flutter

@override  void initState() {    WidgetsBinding.instance.addPostFrameCallback(_afterLayout);    super.initState();  } _afterLayout(_) {    _getSizes();    _getPositions();  }