doctor_app_flutter/lib/widgets/auth/auth_header.dart

import 'package:doctor_app_flutter/lookups/auth_lookup.dart';
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter_device_type/flutter_device_type.dart';

class AuthHeader extends StatelessWidget {
  var userType;
  AuthHeader(this.userType);

  @override
  Widget build(BuildContext context) {
    var smallScreenSize = 660;
    return LayoutBuilder(builder: (ctx, constraints) {
      bool isSmallScreen = constraints.maxWidth <= smallScreenSize;
      var screen = Container(
          margin: isSmallScreen
              ? null
              : EdgeInsetsDirectional.fromSTEB(constraints.maxWidth * 0.30,
                  constraints.maxWidth * 0.1, 0, 0),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: <Widget>[
              Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: <Widget>[
                  Container(
                    margin: isSmallScreen
                        ? EdgeInsetsDirectional.fromSTEB(0, 50, 0, 0)
                        : EdgeInsetsDirectional.fromSTEB(
                            constraints.maxWidth * 0.13, 0, 0, 0),
                    child: Image.asset(
                      'assets/images/login_icon.png',
                      fit: BoxFit.cover,
                      height:
                          isSmallScreen ? null : constraints.maxWidth * 0.09,
                    ),
                  ),
                  SizedBox(
                    height: 10,
                  ),
                  Container(
                    margin: isSmallScreen
                        ? null
                        : EdgeInsetsDirectional.fromSTEB(
                            constraints.maxWidth * 0.13, 0, 0, 0),
                    child: Text(
                      "LOGIN",
                      style: TextStyle(
                          fontSize:
                              isSmallScreen ? 30 : constraints.maxWidth * 0.035,
                          fontWeight: FontWeight.w800),
                    ),
                  )
                ],
              ),
              Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: isSmallScreen
                    ? <Widget>[
                        SizedBox(
                          height: 10,
                        ),
                        buildWelText(isSmallScreen, constraints),
                        buildDrSulText(isSmallScreen, constraints, context),
                      ]
                    : <Widget>[
                        SizedBox(
                          height: 10,
                        ),
                        Row(
                          mainAxisAlignment: MainAxisAlignment.start,
                          children: <Widget>[
                            buildWelText(isSmallScreen, constraints),
                            buildDrSulText(isSmallScreen, constraints, context),
                          ],
                        ),
                      ],
              ),
              buildDrAppContainer(isSmallScreen, constraints, context)
            ],
          ));
      return screen;
    });
  }

  Container buildDrAppContainer(
      bool isSmallScreen, BoxConstraints constraints, BuildContext context) {
    return Container(
      margin: isSmallScreen
          ? null
          : EdgeInsetsDirectional.fromSTEB(
              constraints.maxWidth * 0.13, 0, 0, 0),
      child: Text(
        "Doctor App",
        style: TextStyle(
            fontSize: isSmallScreen ? 26 : constraints.maxWidth * 0.030,
            fontWeight: FontWeight.w800,
            color: Theme.of(context).primaryColor),
      ),
    );
  }

  Text buildDrSulText(
      bool isSmallScreen, BoxConstraints constraints, BuildContext context) {
    return Text(
      'Dr Sulaiman Al Habib',
      style: TextStyle(
        fontWeight: FontWeight.w800,
        fontSize: isSmallScreen ? 24 : constraints.maxWidth * 0.029,
        color: Theme.of(context).primaryColor,
      ),
    );
  }

  Text buildWelText(bool isSmallScreen, BoxConstraints constraints) {
    String text = 'Welcome to ';
    if (userType == loginType.unknownUser) {
      text = 'Welcome Back to';
    }

    return Text(
      text,
      style: TextStyle(
          fontSize: isSmallScreen ? 24 : constraints.maxWidth * 0.029),
    );
  }
}