FractionalOffset alignment

How to align the child within its parent's bounds.

An alignment of (0.0, 0.0) aligns the child to the top-left corner of its parent's bounds. An alignment of (1.0, 0.5) aligns the child to the middle of the right edge of its parent's bounds.

Source 

FractionalOffset get alignment => _alignment;
void alignment=(FractionalOffset newAlignment)

Source 

set alignment (FractionalOffset newAlignment) {
  assert(newAlignment != null && newAlignment.dx != null && newAlignment.dy != null);
  if (_alignment == newAlignment)
    return;
  _alignment = newAlignment;
  _clearPaintData();
  markNeedsPaint();
}