RefreshIndicator constructor

const RefreshIndicator({Key key, @required Widget child, double displacement: 40.0, @required RefreshCallback onRefresh, Color color, Color backgroundColor, ScrollNotificationPredicate notificationPredicate: defaultScrollNotificationPredicate, String semanticsLabel, String semanticsValue })

Creates a refresh indicator.

The onRefresh, child, and notificationPredicate arguments must be non-null. The default displacement is 40.0 logical pixels.

The semanticsLabel is used to specify an accessibility label for this widget. If it is null, it will be defaulted to MaterialLocalizations.refreshIndicatorSemanticLabel. An empty string may be passed to avoid having anything read by screen reading software. The semanticsValue may be used to specify progress on the widget. The

Implementation 

const RefreshIndicator({
  Key key,
  @required this.child,
  this.displacement = 40.0,
  @required this.onRefresh,
  this.color,
  this.backgroundColor,
  this.notificationPredicate = defaultScrollNotificationPredicate,
  this.semanticsLabel,
  this.semanticsValue,
}) : assert(child != null),
     assert(onRefresh != null),
     assert(notificationPredicate != null),
     super(key: key);