Draggable resizable sheet

draggable_resizable sheet.dart

import 'package:flutter/material.dart';

void main() {
  runApp(const MaterialApp(home: MyHomePage()));
}

class MyHomePage extends StatelessWidget {
  const MyHomePage({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: Center(
          child: FilledButton(
              onPressed: () {
                showDraggableResizableSheet(
                  keyboardDismissedSize: .54,
                    context: context,
                    builder: (_, controller) {
                      return ListView.separated(
                        controller: controller,
                        itemCount: 8,
                        itemBuilder: (context, index) => const TextField(),
                        separatorBuilder: (context, index) => const SizedBox.square(dimension: 16),
                      );
                    });
              },
              child: const Text('show modal'))),
    );
  }
}

/// Shows a [DraggableScrollableSheet] with [builder] as content.
/// The scrollController passed to the builder MUST be assigned to the scrollable eg: listview.
/// It automatically expands and contracts when the keyboard is shown/dismissed.
Future<void> showDraggableResizableSheet<T>(
    {required BuildContext context,
    required ScrollableWidgetBuilder builder,
    double initialChildSize = .5,
    double minChildSize = .3,
    double maxChildSize = 1,
    bool shrinkOnKeyboardDismissal = true,
    double keyboardDismissedSize = .8}) async {
  final sheetController = DraggableScrollableController();
  var lastFrameKeyboardShown = false;

  return showModalBottomSheet<T>(
    showDragHandle: true,
    isScrollControlled: true,
    context: context,
    builder: (_) => DraggableScrollableSheet(
        initialChildSize: initialChildSize,
        minChildSize: minChildSize,
        maxChildSize: maxChildSize,
        expand: false,
        controller: sheetController,
        builder: (BuildContext context, ScrollController scrollController) {
          if (context.isKeyboardVisible) {
            sheetController.animateTo(1, duration: const Duration(milliseconds: 150), curve: Curves.easeInOut);
            lastFrameKeyboardShown = true;
          } else if (shrinkOnKeyboardDismissal && !context.isKeyboardVisible && lastFrameKeyboardShown) {
            sheetController.animateTo(keyboardDismissedSize,
                duration: const Duration(milliseconds: 450), curve: Curves.easeInOut);

            lastFrameKeyboardShown = false;
          }
          return Scaffold(
            backgroundColor: Colors.transparent,
            resizeToAvoidBottomInset: true,
            body: builder(context, scrollController),
          );
        }),
  ).then((value) {
    sheetController.dispose();
  });
}

extension ScreenSizeX on BuildContext {
  /// True If the keyboard is visible in the screen
  bool get isKeyboardVisible => MediaQuery.of(this).viewInsets.bottom > 100;
}