axisDirectionToAxis function

Axis axisDirectionToAxis (AxisDirection axisDirection)

Returns the Axis that contains the given AxisDirection.

Specifically, returns Axis.vertical for AxisDirection.up and AxisDirection.down and returns Axis.horizontal for AxisDirection.left and AxisDirection.right.

Implementation 

Axis axisDirectionToAxis(AxisDirection axisDirection) {
  assert(axisDirection != null);
  switch (axisDirection) {
    case AxisDirection.up:
    case AxisDirection.down:
      return Axis.vertical;
    case AxisDirection.left:
    case AxisDirection.right:
      return Axis.horizontal;
  }
  return null;
}