flutter-wonderous-app/lib/ui/common/controls/eight_way_swipe_detector.dart

import 'package:wonders/common_libs.dart';

class EightWaySwipeDetector extends StatefulWidget {
  const EightWaySwipeDetector({super.key, required this.child, this.threshold = 50, required this.onSwipe});
  final Widget child;
  final double threshold;
  final void Function(Offset dir)? onSwipe;

  @override
  State<EightWaySwipeDetector> createState() => _EightWaySwipeDetectorState();
}

class _EightWaySwipeDetectorState extends State<EightWaySwipeDetector> {
  Offset _startPos = Offset.zero;
  Offset _endPos = Offset.zero;
  bool _isSwiping = false;

  void _resetSwipe() {
    _startPos = _endPos = Offset.zero;
    _isSwiping = false;
  }

  void _maybeTriggerSwipe() {
    // Exit early if we're not currently swiping
    if (_isSwiping == false) return;
    // Get the distance of the swipe
    Offset moveDelta = _endPos - _startPos;
    final distance = moveDelta.distance;
    // Trigger swipe if threshold has been exceeded, if threshold is < 1, use 1 as a minimum value.
    if (distance >= max(widget.threshold, 1)) {
      // Normalize the dx/dy values between -1 and 1
      moveDelta /= distance;
      // Round the dx/dy values to snap them to -1, 0 or 1, creating an 8-way directional vector.
      Offset dir = Offset(
        moveDelta.dx.roundToDouble(),
        moveDelta.dy.roundToDouble(),
      );
      widget.onSwipe?.call(dir);
      _resetSwipe();
    }
  }

  void _handleSwipeStart(d) {
    _isSwiping = true;
    _startPos = _endPos = d.localPosition;
  }

  void _handleSwipeUpdate(d) {
    _endPos = d.localPosition;
    _maybeTriggerSwipe();
  }

  void _handleSwipeEnd(d) {
    _maybeTriggerSwipe();
    _resetSwipe();
  }

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
        behavior: HitTestBehavior.translucent,
        onPanStart: _handleSwipeStart,
        onPanUpdate: _handleSwipeUpdate,
        onPanCancel: _resetSwipe,
        onPanEnd: _handleSwipeEnd,
        child: widget.child);
  }
}