RichText({Key key, @required TextSpan text, TextAlign textAlign, bool softWrap: true, TextOverflow overflow: TextOverflow.clip, double textScaleFactor: 1.0 })

Creates a paragraph of rich text.

The text, softWrap, and overflow arguments must not be null.

Source 

RichText({
  Key key,
  @required this.text,
  this.textAlign,
  this.softWrap: true,
  this.overflow: TextOverflow.clip,
  this.textScaleFactor: 1.0
}) : super(key: key) {
  assert(text != null);
  assert(softWrap != null);
  assert(overflow != null);
  assert(textScaleFactor != null);
}