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

Creates a 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 

ProgressIndicator({
  Key key,
  this.value,
  this.backgroundColor,
  this.valueColor
}) : super(key: key);