TabBar constructor
Creates a material design tab bar.
The tabs argument must not be null and its length must match the controller's
TabController.length.
If a TabController is not provided, then there must be a DefaultTabController ancestor.
The indicatorWeight parameter defaults to 2, and must not be null.
The indicatorPadding parameter defaults to EdgeInsets.zero, and must not be null.
If indicator is not null, then indicatorWeight, indicatorPadding, and
indicatorColor are ignored.
Implementation
const TabBar({
Key key,
@required this.tabs,
this.controller,
this.isScrollable = false,
this.indicatorColor,
this.indicatorWeight = 2.0,
this.indicatorPadding = EdgeInsets.zero,
this.indicator,
this.indicatorSize,
this.labelColor,
this.labelStyle,
this.labelPadding,
this.unselectedLabelColor,
this.unselectedLabelStyle,
}) : assert(tabs != null),
assert(isScrollable != null),
assert(indicator != null || (indicatorWeight != null && indicatorWeight > 0.0)),
assert(indicator != null || (indicatorPadding != null)),
super(key: key);