Positioned.directional constructor

Positioned.directional({Key key, @required TextDirection textDirection, double start, double top, double end, double bottom, double width, double height, @required Widget child })

Creates a widget that controls where a child of a Stack is positioned.

Only two out of the three horizontal values (start, end, width), and only two out of the three vertical values (top, bottom, height), can be set. In each case, at least one of the three must be null.

If textDirection is TextDirection.rtl, then the start argument is used for the right property and the end argument is used for the left property. Otherwise, if textDirection is TextDirection.ltr, then the start argument is used for the left property and the end argument is used for the right property.

The textDirection argument must not be null.

See also:

Implementation 

factory Positioned.directional({
  Key key,
  @required TextDirection textDirection,
  double start,
  double top,
  double end,
  double bottom,
  double width,
  double height,
  @required Widget child,
}) {
  assert(textDirection != null);
  double left;
  double right;
  switch (textDirection) {
    case TextDirection.rtl:
      left = end;
      right = start;
      break;
    case TextDirection.ltr:
      left = start;
      right = end;
      break;
  }
  return Positioned(
    key: key,
    left: left,
    top: top,
    right: right,
    bottom: bottom,
    width: width,
    height: height,
    child: child,
  );
}