app_bar.dart

import 'package:flutter/material.dart';

class CustomAppBar extends StatelessWidget {
  final String title;
  const CustomAppBar(
    this.title, {
    Key key,
  }) : super(key: key);
  @override
  Widget build(BuildContext context) {
    MediaQueryData mediaQuery = MediaQuery.of(context);
    double height =
        (mediaQuery.size.height - mediaQuery.padding.top) * HEADER_HEIGHT;
    return Container(
      height: height,
      child: Row(
        children: <Widget>[
          IconButton(
            color: Colors.black,
            icon: Icon(Icons.chevron_left),
            onPressed: () => Navigator.pop(context),
          ),
          Text(title)
        ],
      ),
    );
  }
}