CircularProgressIndicator({Key key, double value, Color backgroundColor, Animation<Color> valueColor })

Creates a circular progress indicator.

The value argument can be either null (corresponding to an indeterminate progress indcator) or non-null (corresponding to a determinate progress indicator). See value for details.

Source 

CircularProgressIndicator({
  Key key,
  double value,
  Color backgroundColor,
  Animation<Color> valueColor
}) : super(key: key, value: value, backgroundColor: backgroundColor, valueColor: valueColor);