automaticValuePosition method
Implementation
ValuePosition automaticValuePosition(
  PdfPoint point,
  PdfPoint size,
  PdfPoint? previous,
  PdfPoint? next,
) {
  // Usually on top, except on the edges
  if (point.x - size.x / 2 < box!.left) {
    return ValuePosition.right;
  }
  if (point.x + size.x / 2 > box!.right) {
    return ValuePosition.left;
  }
  if (point.y + size.y + delta > box!.top) {
    return ValuePosition.bottom;
  }
  return ValuePosition.top;
}