setState method
Schedule a call to buildTransitions.
Whenever you need to change internal state for a TransModalRoute object, make the change in a function that you pass to setState, as in:
setState(() { _myState = newValue; });
If you just change the state directly without calling setState, then the route will not be scheduled for rebuilding, meaning that its rendering will not be updated.
Implementation
@protected
void setState(VoidCallback fn) {
if (_scopeKey.currentState != null) {
_scopeKey.currentState!._routeSetState(fn);
} else {
// The route isn't currently visible, so we don't have to call its setState
// method, but we do still need to call the fn callback, otherwise the state
// in the route won't be updated!
fn();
}
}