boundaryToward method

@override DiagramPoint boundaryToward(DiagramPoint target)

Implementation

@override
DiagramPoint boundaryToward(DiagramPoint target) {
  final center = bounds.center;
  final delta = target - center;
  if (delta.x == 0 && delta.y == 0) return center;
  final xScale = delta.x == 0
      ? double.infinity
      : bounds.width / 2 / delta.x.abs();
  final yScale = delta.y == 0
      ? double.infinity
      : bounds.height / 2 / delta.y.abs();
  final rectangularHit = center + delta * math.min(xScale, yScale);
  final radius = effectiveCornerRadius;
  if (radius == 0 ||
      (rectangularHit.x >= bounds.left + radius &&
          rectangularHit.x <= bounds.right - radius) ||
      (rectangularHit.y >= bounds.top + radius &&
          rectangularHit.y <= bounds.bottom - radius)) {
    return rectangularHit;
  }
  // Only a corner arc can exclude a point on the rectangular perimeter.
  // Intersect the center ray with that corner's circle, taking the far root:
  // the near root belongs to the interior, outside the corner's quadrant.
  final corner = DiagramPoint(
    rectangularHit.x < center.x
        ? bounds.left + radius
        : bounds.right - radius,
    rectangularHit.y < center.y
        ? bounds.top + radius
        : bounds.bottom - radius,
  );
  final ray = rectangularHit - center;
  final direction = ray * (1 / ray.magnitude);
  final offset = corner - center;
  final along = offset.x * direction.x + offset.y * direction.y;
  final across = offset.x * direction.y - offset.y * direction.x;
  final distance =
      along + math.sqrt(math.max(0, radius * radius - across * across));
  return center + direction * distance;
}