import 'package:flutter/material.dart';

class GrantScreen {

  static double _width, _height;

  static double _physicalWidth, _physicalHeight;

  static double _top, _bottom;

  static double _scaleWidth, _scaleHeight;

  static double _textScale;

  static double _pixelRatio;

  GrantScreen(BuildContext context){

    _physicalWidth = MediaQuery.of(context).size.width;

    _physicalHeight = MediaQuery.of(context).size.height;

    _top = MediaQuery.of(context).padding.top;

    _bottom = MediaQuery.of(context).padding.bottom;

    _textScale = MediaQuery.of(context).textScaleFactor;

    _width = 375.0;

    _height = 667.0;

    _scaleWidth = _physicalWidth / _width;

    _scaleHeight = _physicalHeight / _height;

    _pixelRatio = MediaQuery.of(context).devicePixelRatio;

  }

  get top => _top / _scaleHeight;

  get bottom => _bottom / _scaleHeight;

  get scaleWidth => _scaleWidth;

  get scaleHeight => _scaleHeight;

  get width => _width;

  get height => _height;

  get pixelRatio => _pixelRatio;

  get physicalWidth => _physicalWidth;

  get physicalHeight => _physicalHeight;

  setWidth(double w) => w * _scaleWidth;

  setHeight(double h) => h * _scaleHeight;

  setFontSize(double f, [bool allowScale=true]) =>

      allowScale? setWidth(f)/_textScale : f/_textScale;

  getGlobalPosition(DragDownDetails details){

    double dx = details.globalPosition.dx / _scaleWidth;

    double dy = details.globalPosition.dy / _scaleHeight;

    return DragDownDetails(globalPosition: Offset(dx, dy));

  }

}

import 'package:flutter/material.dart';

import 'screen.dart';

main() => runApp(MaterialApp(

  home: MyApp(),

));

class MyApp extends StatelessWidget {

  @override

  Widget build(BuildContext context) {

    var x = MediaQuery.of(context).size;

    print('original size: $x');

    GrantScreen screen = GrantScreen(222, 444, context);

    return RootWidget(

      child: HomePage(),

      screen: screen,

    );

  }

}

class RootWidget extends InheritedWidget {

  RootWidget({Key key, @required this.child, this.screen}):super(key:key);

  final GrantScreen screen;

  final Widget child;

  static RootWidget of(BuildContext context){

    return context.inheritFromWidgetOfExactType(RootWidget);

  }

  @override

  bool updateShouldNotify(InheritedWidget oldWidget) {

    return true;

  }

}

class HomePage extends StatelessWidget {

  @override

  Widget build(BuildContext context) {

    var s = RootWidget.of(context).screen;

    return Scaffold(

      appBar: AppBar(title: Text('ABC', style: TextStyle(fontSize: 22),),),

      body: GestureDetector(

        onPanDown: (DragDownDetails details){

          print('mmmmmmmmmmmmmmmmmmmmmm');

          print(details);

          print(s.getGlobalPosition(details));

          print('new top: ${s.top}');

          print(MediaQuery.of(context).padding.top);

          print('mmmmmmmmmmmmmmmmmmmmmmmm');

        },

        child: Container(

        width: double.infinity,height: double.infinity,

        color: Colors.grey,

        child: Column(

          children: <Widget>[

            Text('Text', style: TextStyle(fontSize: s.setFontSize(44, true)),),

            Text('Text', style: TextStyle(fontSize: s.setFontSize(44, false)),),

            Text('Text', style: TextStyle(fontSize: 44),),

          ],

        ),

      ),),

    );

  }

}

import 'package:flutter/material.dart';

class GrantScreen {

  static double _width, _height;

  static double _physicalWidth, _physicalHeight;

  static double _top, _bottom;

  static double _scaleWidth, _scaleHeight;

  static double _textScale;

  static double _pixelRatio;

  GrantScreen(double w, double h, BuildContext context){

    _physicalWidth = MediaQuery.of(context).size.width;

    _physicalHeight = MediaQuery.of(context).size.height;

    _top = MediaQuery.of(context).padding.top;

    _bottom = MediaQuery.of(context).padding.bottom;

    _textScale = MediaQuery.of(context).textScaleFactor;

    _width = w;

    _height = h;

    _scaleWidth = _physicalWidth / w;

    _scaleHeight = _physicalHeight / h;

    _pixelRatio = MediaQuery.of(context).devicePixelRatio;

  }

  get top => _top / _scaleHeight;

  get bottom => _bottom / _scaleHeight;

  get scaleWidth => _scaleWidth;

  get scaleHeight => _scaleHeight;

  get width => _width;

  get height => _height;

  get pixelRatio => _pixelRatio;

  get physicalWidth => _physicalWidth;

  get physicalHeight => _physicalHeight;

  setWidth(double w) => w * _scaleWidth;

  setHeight(double h) => h * _scaleHeight;

  setFontSize(double f, [bool allowScale=true]) =>

    allowScale? setWidth(f)/_textScale : f/_textScale;

  getGlobalPosition(DragDownDetails details){

    double dx = details.globalPosition.dx / _scaleWidth;

    double dy = details.globalPosition.dy / _scaleHeight;

    return DragDownDetails(globalPosition: Offset(dx, dy));

  }

}