responsive_widget.dart

class ResponsiveWidget extends StatelessWidget {
  final Widget smallScreen;
  final Widget mediumScreen;
  final Widget largeScreen;

  const ResponsiveWidget({Key key,
    this.mediumScreen,
    @required this.smallScreen,
    this.largeScreen})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    //Returns the widget which is more appropriate for the screen size
    return LayoutBuilder(builder: (context, constraints) {
      if (constraints.maxWidth > 1200) {
        return largeScreen;
      } else if (constraints.maxWidth > 800 && constraints.maxWidth < 1200) {
        //if medium screen not available, then return large screen
        return mediumScreen ?? largeScreen;
      } else {
        //if small screen implementation not available, then return large screen
        return smallScreen;
      }
    });
  }
}