Flutter popup menu button triggered by long press.

long_press_menu_button.dart

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

class LongPressMenuButton extends StatefulWidget {
  final Widget child;
  final List<PopupMenuEntry> items;
  final bool enabled;
  final bool hapticFeedback;
  const LongPressMenuButton({
    super.key,
    required this.child,
    required this.items,
    this.enabled = true,
    this.hapticFeedback = true,
  });

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

class LongPressMenuButtonState extends State<LongPressMenuButton> {
  Offset _tapPosition = Offset.zero;

  void _setTapPosition(TapDownDetails details) {
    final RenderBox refBox = context.findRenderObject() as RenderBox;
    setState(() => _tapPosition = refBox.localToGlobal(details.localPosition));
  }

  void _showContextMenu() async {
    final overlay = Overlay.of(context).context.findRenderObject();
    final rect = _tapPosition & const Size(40, 40);
    final container = Offset.zero & overlay!.semanticBounds.size;
    showMenu(
      context: context,
      position: RelativeRect.fromRect(rect, container),
      items: widget.items,
    );
    if (widget.hapticFeedback) HapticFeedback.selectionClick();
  }

  @override
  Widget build(BuildContext context) {
    return widget.enabled
        ? GestureDetector(
            onTapDown: _setTapPosition,
            onLongPress: _showContextMenu,
            child: widget.child,
          )
        : widget.child;
  }
}