custom_back_drop

gistfile1.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

const horizontalPadding = 16.0;
const controllerBorderRadius = BorderRadius.all(Radius.circular(2.0));
const controllerHeight = 4.0;
const controllerWidth = 32.0;
const systemAppBarHeight = 48.0;
const keyboardHeight = 282;

Future<T> showCustomModalBottomSheet<T>({BuildContext context, Widget child, Color backgroundColor, double 
topPadding}) {
  return showModalBottomSheet<T>(
      backgroundColor: Colors.transparent,
      isScrollControlled: true,
      context: context,
      builder: (ctx) {
        return _BackDropBody(child: child, topPadding: MediaQuery.of(context).padding.top);
      });
}

class _BackDropBody extends StatefulWidget {
  final Widget child;
  final double topPadding;

  const _BackDropBody({Key key, this.child, this.topPadding}) : super(key: key);

  @override
  __BackDropBodyState createState() => __BackDropBodyState();
}

class __BackDropBodyState extends State<_BackDropBody> {
  @override
  Widget build(BuildContext context) {
    return ConstrainedBox(
      constraints: BoxConstraints(maxHeight: MediaQuery.of(context).size.height - widget.topPadding),
      child: DraggableScrollableSheet(
          expand: false,
          maxChildSize: 1,
          initialChildSize: 0.9999,
          minChildSize: 0.9999,
          builder: (context, sc) {
            return AnimatedContainer(
              curve: Curves.easeInOutQuart,
              duration: const Duration(milliseconds: 300),
              padding: EdgeInsets.only(
                  top: MediaQuery.of(context).padding.top, bottom: MediaQuery.of(context).viewInsets.bottom),
              child: Stack(
                children: <Widget>[
                  Container(
                    decoration: BoxDecoration(
                        color: OzonColors.ozWhite1,
                        borderRadius:
                            BorderRadius.only(topLeft: Radius.circular(16.0), topRight: Radius.circular(16.0))),
                    child: SingleChildScrollView(
                      controller: sc,
                      child: widget.child,
                      physics: const BouncingScrollPhysics(),
                    ),
                  ),
                  Container(
                    height: 20,
                    color: Colors.transparent,
                    alignment: Alignment.center,
                    child: Container(
                      decoration: BoxDecoration(
                        color: OzonColors.ozGray70,
                        borderRadius: controllerBorderRadius,
                      ),
                      height: controllerHeight,
                      width: controllerWidth,
                    ),
                  ),
                ],
              ),
            );
          }),
    );
  }
}