Picture - composite structured graphic

       A  Picture  defines  a  composition  of  graphic objects.  A picture has its own graphics state, which it
       concatenates with its children's  state  when  it  is  drawn  or  erased.   Picture  adopts  the  default
       concatenation  semantics  supported  by  the Graphic base class: The picture's graphics state effectively
       overrides its children's so that they are drawn with the  picture's  state  information  substituted  for
       their own.  A child's attribute is used only when the picture does not already define it.  Moreover, each
       child's  transformer  is  postmultiplied  by  the  picture's  transformer when the picture is drawn; thus
       children are drawn relative to the picture's coordinate system.

       Picture - composite structured graphic

Graphic*graphic(UList*)UList*Elem(Iterator)
              Convenience functions for extracting a graphic from a UList element and a UList from an iterator.

Picture(Graphic*=nil)
              Construct a new picture, optionally supply a graphic from which to copy an initial set of graphics
              state.  Picture is derived from FullGraphic and therefore defines a full set of graphics state.

       virtual~Picture()
              The picture deletes its children when it is deleted.

       booleanIsEmpty()
              Picture defines IsEmpty in addition to the standard Graphic child traversal operations to  provide
              a convenient way to check if the picture has any children.

Graphic(3U), Iterator(3U), Transformer(3I), UList(3U), pspaint(3U)

Unidraw                                          1 February 1991                                     Picture(3U)

#include<Unidraw/Graphic/picture.h>