1. override
void performAction(SemanticsAction action)

Called when the object implementing this interface receives a SemanticsAction. For example, if the user of an accessibility tool instructs their device that they wish to tap a button, the RenderObject behind that button would have its performAction method called with the SemanticsAction.tap action.

Source 

@override
void performAction(SemanticsAction action) {
  if (action == SemanticsAction.tap)
    _handleTap();
}