replaceSemanticsActions method

void replaceSemanticsActions (Set<SemanticsAction> actions)

This method can be called outside of the build phase to filter the list of available semantic actions.

The actual filtering is happening in the next frame and a frame will be scheduled if non is pending.

This is used by Scrollable to configure system accessibility tools so that they know in which direction a particular list can be scrolled.

If this is never called, then the actions are not filtered. If the list of actions to filter changes, it must be called again.

Implementation 

void replaceSemanticsActions(Set<SemanticsAction> actions) {
  assert(() {
    final Element element = context;
    if (element.owner.debugBuilding) {
      throw FlutterError(
        'Unexpected call to replaceSemanticsActions() method of RawGestureDetectorState.\n'
        'The replaceSemanticsActions() method can only be called outside of the build phase.'
      );
    }
    return true;
  }());
  if (!widget.excludeFromSemantics) {
    final RenderSemanticsGestureHandler semanticsGestureHandler = context.findRenderObject();
    semanticsGestureHandler.validActions = actions; // will call _markNeedsSemanticsUpdate(), if required.
  }
}