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 alignment property's WrapAlignment.start and WrapAlignment.end values.

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

If the direction is Axis.vertical, this controls the order in which runs are positioned, the meaning of the runAlignment property's WrapAlignment.start and WrapAlignment.end values, as well as the crossAxisAlignment property's WrapCrossAlignment.start and WrapCrossAlignment.end values.

If the direction is Axis.vertical, and either the runAlignment is either WrapAlignment.start or WrapAlignment.end, the crossAxisAlignment is either WrapCrossAlignment.start or WrapCrossAlignment.end, or there's more than one child, 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();
  }
}