🚀 go-pugleaf

In article <22JUL199210554136@mary.fordham.edu>
	sbhatia@mary.fordham.edu (SABU) writes:
>I seem to be getting very confused about what exactly is a workstation in
>PHIGS.

A workstation in PHIGS is an abstraction of a physical display
surface.  Under PEX, this means the interior portion of an X window
(in other words, it doesn't include the X window's border).

>Is a workstation in PHIGS a physical resource such as a terminal,
>or a remore system etc? If not what exactly is meant by "WORKSTATION".

From the standard (ISO/IEC 9592-1:1988(E), page 14):

    ``{\em workstation}: PHIGS is based on the concept of abstract graphical
    resources, whic provide the logical interface through which the
    application program controls physical devices.  A workstation
    consists of zero or one {\em display space} and zero or more {\em
    logical input devices}.''

and display space is defined as (page 7):

    ``{\em display space}:
    (1) That portion of {\em device space} corresponding to the volume
    availkable for displaying {\em images}.
    (2) The working space of an input device.  (Taken from ISO 7942
    and ISO 8805)''

>Secondly in PHIGS we have [the four state variables]:
>PHIGS, WORKSTATION, STRUCTURE, ARCHIVE
>
>My understanding of the above mentioned is that in order to use
>a wokstation we musty have phigs open similar is the case
>with structure and archive. but what happens from workstation
>downwards.

Not quite.  You need to have PHIGS open before any PHIGS call can be
made.  Structure-oriented calls (like editing elements, replacing
elements, creating elements, moving the element pointer, etc.) usually
require a structure be open.  Similarly, archive-oriented calls
usually require than an archive file be open.  Workstation calls
usually require that a workstation be opened as you might expect.
Each function usually has an indicator of the required states for its
use:

    (PHOP, *, *, *)	Requires only PHIGS be open
    (PHOP, WSOP, *, *)	Requires PHIGS and workstation open
    (PHOP, *, STOP, *)	Requires PHIGS and structure open
    (PHOP, *, *, AROP)	Requires PHIGS and archive file open

and so on.  The PEX man pages provide this information just after the
C function template for the routine at the top of the manual page
under the heading "Required PHIGS Operating States".  Similarly, the
PHIGS standard uses the same notation to indicate the state required
by each function.  The "*" in the above notation indicates that the
state variable in question can be either open or closed -- it doesn't
matter.

>I would appreciate
>it if someone could explain to me the structure of these states and
>their inter relationship, or indicate some resource (book, or ftp site)
>where I can get some decent information.

The meaning of these states and how they are changed is covered very
well in this book:

    ``PHIGS Programming Manual'', by Tom Gaskins
    ISBN 0-937175-85-4 (softcover)
    ISBN 0-937175-92-7 (casebound)

    O'Reilly & Associates
    103 Morriss Street, Suite A
    Sebastopol, California 95472
    (800) 338-6887 US/Canada
    (707) 829-0515 overseas/local
    (707) 829-0104 FAX

						-- Rich
-- 
	Repeal the personal income tax; vote Libertarian in 1992.
Disclaimer: I speak for myself, except as noted; Copyright 1992 Rich Thomson
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