HeaderFragment.player_progress_ visibility.HeaderFragment.reading_pager_ below header.HeaderFragment.player_button_ ui state to error.HeaderFragment.reading_pager_ PagerFragment height.HeaderFragment.player_button_ ui state to skip.HeaderFragment.player_button_ ui state to pause.HeaderFragment.player_button_ ui state to play.HeaderFragment.player_button_ ui state to replay.Place.AppTrigger.enter if the user is within;
Place.AppTrigger.exit if the user is at least Constants.DISTANCE_PLACE_VISIBILITY meters away;
Place.stop() otherwise.
IEvent implementation for UI related events.