barrierLabel property Null safety

The semantic label used for a dismissible barrier.

If the barrier is dismissible, this label will be read out if accessibility tools (like VoiceOver on iOS) focus on the barrier.

The modal barrier is the scrim that is rendered behind each route, which generally prevents the user from interacting with the route below the current route, and normally partially obscures such routes.

For example, when a dialog is on the screen, the page below the dialog is usually darkened by the modal barrier.

If this getter would ever start returning a different label, either changedInternalState or changedExternalState should be invoked so that the change can take effect.

It is safe to use navigator.context to look up inherited widgets here, because the Navigator calls changedExternalState whenever its dependencies change, and changedExternalState causes the modal barrier to rebuild.

See also:

• barrierDismissible, which controls the behavior of the barrier when tapped.
• ModalBarrier, the widget that implements this feature.