Clipboard - manages a list of graphical component subjects

SYNOPSIS

       #include <Unidraw/clipboard.h>

DESCRIPTION

       A Clipboard maintains a list of  GraphicComp  objects  and
       provides  operations  for  manipulating the list.  Catalog
       and Command classes use clipboards to store graphical com-
       ponents they affect.

PUBLIC OPERATIONS

       Clipboard(GraphicComp* = nil)
              Construct a new clipboard object, optionally with a
              GraphicComp that should  appear  initially  on  the
              list.

       virtual ~Clipboard()
              Delete  the clipboard.  Deleting the clipboard does
              not delete the GraphicComp objects it contains.

       void Init(Selection*)
       void CopyInit(Selection*)
              Init initializes the clipboard  with  the  subjects
              belonging  to  the  graphical  views  in  the given
              selection object.   CopyInit  initializes  it  with
              copies of the subjects.

       void Clear()
              Remove  all GraphicComp objects from the clipboard.
              The objects are not deleted.

       void DeleteComps()
              Delete each GraphicComp  in  the  clipboard.   This
              operation  does not delete the list itself; thus it
              will still be possible to iterate through the  list
              afterwards.   DeleteComps  is generally called just
              before the clipboard is destroyed.

       void Append(GraphicComp*)
       void Prepend(GraphicComp*)
       void InsertAfter(Iterator, GraphicComp*)
       void InsertBefore(Iterator, GraphicComp*)
       void Remove(GraphicComp*)
       void Remove(Iterator&)
              Operations  for  adding  and  removing  GraphicComp
              objects   from   the  clipboard.   InsertAfter  and
              InsertBefore take an iterator  that  specifies  the
              point  before  or after which the given GraphicComp
              should be inserted.  Remove(Iterator&) removes  the
              GraphicComp to which the iterator refers and incre-
              ments the iterator to point to the following Graph-

       void SetComp(GraphicComp*, Iterator&)
              GetComp   effectively   dereferences  an  iterator,
              returning the GraphicComp to which it points.  Set-
              Comp  initializes an iterator to point to the given
              GraphicComp object, assuming the object is  in  the
              clipboard.

       void First(Iterator&)
       void Last(Iterator&)
       void Next(Iterator&)
       void Prev(Iterator&)
       boolean Done(Iterator&)
              Operations  for  iterating through the GraphicComps
              in the clipboard.  First and Last modify the itera-
              tor  to  point  to  the  first and last GraphicComp
              objects.  Next and Prev make the iterator point  to
              the  succeeding  and preceding GraphicComp objects.
              Done returns whether the  iterator  points  to  the
              sentinel object on the list, which marks the begin-
              ning and the end of list.

       boolean IsEmpty()
       boolean Includes(GraphicComp*)
              Return whether or not the  clipboard  is  empty  or
              whether it includes the given GraphicComp object.

       virtual Clipboard* Copy()
       virtual Clipboard* DeepCopy()
              Copy  creates  a  new  clipboard with a list of the
              same GraphicComp objects as this.  DeepCopy creates
              a new clipboard containing copies of the objects in
              this.

PROTECTED OPERATIONS

       UList* Elem(Iterator)
       GraphicComp* Comp(UList*)
              The Clipboard class stores its GraphicComp  objects
              in a UList.  These convenience functions convert an
              iterator into a UList  element  and  dereference  a
              UList  element  to  obtain  a  GraphicComp  object,
              respectively.

SEE ALSO

       Catalog(3U), Command(3U),  GraphicComp(3U),  Iterator(3U),
       Selection(3U), UList(3U)