Create custom popup menu

ButtonPopupMenu.dart

import 'package:flutter/material.dart';

class ButtonPopupMenu extends StatefulWidget {
  final Text label;
  final Icon? icon;
  final Widget content;
  final double width;
  final double height;

  const ButtonPopupMenu(
      {Key? key,
      this.icon,
      required this.content,
      required this.label,
      this.width = 300,
      this.height = 300})
      : super(key: key);

  @override
  State<ButtonPopupMenu> createState() => _ButtonPopupMenuState();
}

class _ButtonPopupMenuState extends State<ButtonPopupMenu>
    with SingleTickerProviderStateMixin {
  final GlobalKey _key = GlobalKey<State>();
  OverlayEntry? _entry;
  bool status = false;

  void _closeMenu() {
    _entry?.remove();
    _entry = null;
    setState(() {
      status = false;
    });
  }

  void _openMenu() {
    RenderBox? renderBox =
        _key.currentContext?.findRenderObject() as RenderBox?;
    if (renderBox != null) {
      final offset = renderBox.localToGlobal(Offset.zero);
      final buttonSize = renderBox.size;

      _entry = _overlayEntryBuilder(offset, buttonSize);
      if (_entry != null) {
        Overlay.of(context)?.insert(_entry!);
        setState(() {
          status = true;
        });
      }
    }
  }

  OverlayEntry _overlayEntryBuilder(Offset offset, Size buttonSize) {
    return OverlayEntry(
      builder: (_) => Stack(children: [
        Positioned.fill(
            child: GestureDetector(
          onTapDown: (_) => _closeMenu(),
        )),
        Positioned(
          top: offset.dy + buttonSize.height,
          left: offset.dx,
          width: widget.width,
          child: Stack(
            children: <Widget>[
              Padding(
                padding: const EdgeInsets.only(top: 4.0),
                child: Container(
                  height: widget.height,
                  width: widget.width,
                  decoration: BoxDecoration(
                    color: Colors.white,
                    // borderRadius: _borderRadius,
                  ),
                  child: widget.content,
                ),
              ),
            ],
          ),
        ),
      ]),
    );
  }

  @override
  Widget build(BuildContext context) {
    return IgnorePointer(
      ignoring: _entry != null ? true : false,
      child: InkWell(
        key: _key,
        onTap: () => _openMenu(),
        child: Container(
          child: Row(
            children: [
              if (widget.icon != null) widget.icon!,
              widget.label,
              Text(status.toString()),
            ],
          ),
        ),
      ),
    );
  }
}