textDirection property

TextDirection textDirection

Determines the order to lay children out horizontally and how to interpret start and end in the horizontal direction.

If the direction is Axis.horizontal, this controls the order in which children are positioned (left-to-right or right-to-left), and the meaning of the mainAxisAlignment property's MainAxisAlignment.start and MainAxisAlignment.end values.

If the direction is Axis.horizontal, and either the mainAxisAlignment is either MainAxisAlignment.start or MainAxisAlignment.end, or there's more than one child, then the textDirection must not be null.

If the direction is Axis.vertical, this controls the meaning of the crossAxisAlignment property's CrossAxisAlignment.start and CrossAxisAlignment.end values.

If the direction is Axis.vertical, and the crossAxisAlignment is either CrossAxisAlignment.start or CrossAxisAlignment.end, then the textDirection must not be null.

Implementation 

TextDirection get textDirection => _textDirection;
void textDirection= (TextDirection value)

Implementation 

set textDirection(TextDirection value) {
  if (_textDirection != value) {
    _textDirection = value;
    markNeedsLayout();
  }
}