verticalDirection property
Determines the order to lay children out vertically and how to interpret
start and end in the vertical direction.
Defaults to VerticalDirection.down.
If the direction is Axis.vertical, this controls which order children
are painted in (down or up), the meaning of the mainAxisAlignment
property's MainAxisAlignment.start and MainAxisAlignment.end values.
If the direction is Axis.vertical, and either the mainAxisAlignment
is either MainAxisAlignment.start or MainAxisAlignment.end, or there's
more than one child, then the verticalDirection must not be null.
If the direction is Axis.horizontal, this controls the meaning of the
crossAxisAlignment property's CrossAxisAlignment.start and
CrossAxisAlignment.end values.
If the direction is Axis.horizontal, and the crossAxisAlignment is
either CrossAxisAlignment.start or CrossAxisAlignment.end, then the
verticalDirection must not be null.
Implementation
final VerticalDirection verticalDirection;