Flutter Modal bottom sheet that supports full screen height

FullBottomSheet.dart

//Flutter Modal Bottom Sheet
//Modified by Shvet for null safety & tested. Also added Round corners on top.
//Based on https://gist.github.com/GiorgioBertolotti/5fc8fcca67aeda3ed9bbc74c856d06f1

import 'dart:async';

import 'package:flutter/material.dart';

const Duration _kBottomSheetDuration = const Duration(milliseconds: 200);

class _ModalBottomSheetLayout extends SingleChildLayoutDelegate {
  _ModalBottomSheetLayout(this.progress, this.bottomInset, this.statusBarHeight);

  final double progress;
  final double bottomInset;
  final double statusBarHeight;

  @override
  BoxConstraints getConstraintsForChild(BoxConstraints constraints) {
    return new BoxConstraints(
        minWidth: constraints.maxWidth,
        maxWidth: constraints.maxWidth,
        minHeight: 0.0,
        maxHeight: constraints.maxHeight - statusBarHeight);
  }

  @override
  Offset getPositionForChild(Size size, Size childSize) {
    return new Offset(0.0, size.height - bottomInset - childSize.height * progress);
  }

  @override
  bool shouldRelayout(_ModalBottomSheetLayout oldDelegate) {
    return progress != oldDelegate.progress || bottomInset != oldDelegate.bottomInset;
  }
}

class _ModalBottomSheet<T> extends StatefulWidget {
  const _ModalBottomSheet({Key? key, required this.route}) : super(key: key);

  final _ModalBottomSheetRoute<T> route;

  @override
  _ModalBottomSheetState<T> createState() => new _ModalBottomSheetState<T>();
}

class _ModalBottomSheetState<T> extends State<_ModalBottomSheet<T>> {
  @override
  Widget build(BuildContext context) {
    return new GestureDetector(
      onTap: widget.route.dismissOnTap! ? () => Navigator.pop(context) : null,
      child: new AnimatedBuilder(
        animation: widget.route.animation!,
        builder: (BuildContext context, Widget? child) {
          double bottomInset = widget.route.resizeToAvoidBottomPadding! ? MediaQuery.of(context).viewInsets.bottom : 0.0;
          return new ClipRect(
            child: new CustomSingleChildLayout(
              delegate: new _ModalBottomSheetLayout(
                widget.route.animation!.value,
                bottomInset,
                widget.route.statusBarHeight!,
              ),
              child: new BottomSheet(
                animationController: widget.route._animationController,
                onClosing: () => Navigator.pop(context),
                builder: widget.route.builder!,
                shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.vertical(top: Radius.circular(5.0)),
                ),
              ),
            ),
          );
        },
      ),
    );
  }
}

class _ModalBottomSheetRoute<T> extends PopupRoute<T> {
  final WidgetBuilder? builder;
  final ThemeData? theme;
  final bool? resizeToAvoidBottomPadding;
  final bool? dismissOnTap;
  final double? statusBarHeight;

  _ModalBottomSheetRoute({
    this.builder,
    this.theme,
    required this.barrierLabel,
    RouteSettings? settings,
    this.resizeToAvoidBottomPadding,
    this.dismissOnTap,
    this.statusBarHeight,
  }) : super(settings: settings);

  @override
  Duration get transitionDuration => _kBottomSheetDuration;

  @override
  bool get barrierDismissible => false;

  @override
  final String barrierLabel;

  @override
  Color get barrierColor => Colors.black54;

  AnimationController? _animationController;

  @override
  AnimationController createAnimationController() {
    assert(_animationController == null);
    _animationController = BottomSheet.createAnimationController(navigator!.overlay!);
    return _animationController!;
  }

  @override
  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation) {
    Widget bottomSheet = new MediaQuery.removePadding(
      context: context,
      removeTop: true,
      child: new _ModalBottomSheet<T>(route: this),
    );
    if (theme != null)
      bottomSheet = new Theme(
        data: theme!,
        child: bottomSheet,
      );
    return bottomSheet;
  }
}

Future<T?> showModalBottomSheetApp<T>({
  required BuildContext context,
  required WidgetBuilder builder,
  bool dismissOnTap: false,
  bool resizeToAvoidBottomPadding: true,
  double statusBarHeight: 0,
}) {
  return Navigator.push(
      context,
      _ModalBottomSheetRoute<T>(
        builder: builder,
        theme: Theme.of(context),
        barrierLabel: MaterialLocalizations.of(context).modalBarrierDismissLabel,
        resizeToAvoidBottomPadding: resizeToAvoidBottomPadding,
        dismissOnTap: dismissOnTap,
        statusBarHeight: statusBarHeight,
      ));
}