GVUpdater - updates GraphicViews structure to match its subject

       GVUpdater  is  an  implementation class that GraphicViews uses to keep its state and structure consistent
       with its GraphicComps subject.  GVUpdater ensures that subject's immediate children are identical to  the
       view's  in  number  and  graphics  state  attributes.  It  also  ensures  that  the root GraphicViews and
       GraphicComps themselves have the same graphics state.  GVUpdater does not ensure that it will detect  and
       update changes made to deeper child nodes.

       GVUpdater - updates GraphicViews structure to match its subject

voidUpdateStructure()voidUpdateState()
              The  Update  procedure  takes  place  in  two  stages.   The  subject's  and view's structures are
              reconciled first by UpdateStructure, and then the view's graphic state is  changed  to  match  the
              subjects with UpdateState.

       voidAddDamage(Graphic*)voidIncurDamage(Graphic*)voidUnselect(GraphicView*)virtualvoidAdd(GraphicView*)virtualvoidAppend(GraphicView*)virtualvoidInsertBefore(Iterator,GraphicView*)virtualvoidRemove(Iterator&)virtualvoidDeleteView(Iterator&)
              GVUpdater  is  a friend of GraphicViews.  These convenience operations provide an interface to the
              corresponding protected GraphicViews operations.

       virtualClassIdViewCategory()
              Returns the view category (see classes(3U)) GVUpdater will use to instantiate views  of  subjects.
              ViewCategory returns COMPONENT_VIEW by default.

GVUpdater(GraphicView*)
              The constructor takes the GraphicView that it will be updating as a parameter and stores it in the
              protected member _gv. Normally, GraphicViews are the only objects that will instantiate GVUpdater.

       virtualvoidUpdate()
              Update the GraphicView to make it consistent with its subject.

GraphicComp(3U), GraphicView(3U), classes(3U)

Unidraw                                          19 January 1991                                   GVUpdater(3U)

#include<Unidraw/Components/gvupdater.h>