Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!spool.mu.edu!uunet!pictel!harling
From: harling@pictel.uucp (Dan Harling)
Newsgroups: comp.windows.open-look
Subject: Re: Help modifying textsw scrollbar
Message-ID: <1991Jun24.170403.1381@pictel.uucp>
Date: 24 Jun 91 17:04:03 GMT
Article-I.D.: pictel.1991Jun24.170403.1381
References: <1991Jun20.210038.5036@pictel.uucp> <jcb.677539093@lupine>
Sender: Dan Harling
Organization: PictureTel Corporation
Lines: 63

In article <jcb.677539093@lupine> jcb@NCD.COM (Jim Becker) writes:
>harling@pictel.uucp (Dan Harling) writes:
>    I know that my proportioning code is correct, because the horizontal
>    scrollbar moves as expected.  I suspect that the text window still has
>    a handle to the vertical scrollbar, and is reproportioning it
>    automatically, but I have been unable to eliminate this.  If I destroy
>    the original scrollbar and try to create a new one, no vertical
>    scrollbar appears at all.
>
>the vertical scrollbar is  _owned_  by  the  TEXTSW  object,  and  you
>shouldn't be trying to set it. you can't subvert it, as it  knows  how
>many lines are in the TEXTSW content and sets the scrollbar to reflect
>this. it's not under your domain to change.

I realize that the TEXTSW vertical scrollbar is not intended to be
changed.  However, in order to have the scrollbar do something other
than the default functions, I must either redefine some of its
characteristics, or replace it with another scrollbar.

Redefining the scrollbar has been quite successful: it does everything
it is supposed to do (determine the new origin and redraw the display)
except move the elevator.  Similar code for the horizontal scrollbar,
which I created separately, works properly.  Replacing it with a new
one has failed miserably; either no scrollbar appears, or the default
one covers over the new one, making it inaccessible.

I am quite familiar with the obstacles involved in what I am
attempting.  The XView manual even bails out when it comes to doing
anything custom with scrollbars.  It should not be this difficult, but
the documentation is sadly lacking.  In short, I have already heard all
the reasons why I *shouldn't* do this; so far, nobody has shown me that
it *can't* be done (e.g., that the code which automatically sets the
scrollbar properties according to the window contents, overriding my
values, cannot be overridden).


>sounds  like  you  want  to  use  a  CANVAS,  and do your own attached
>scrollbars  to  it.

Unfortunately, there are three reasons I decided not to use the
CANVAS package, if I can avoid it:

1) The display routines already exist in another module, and are
   written for text windows.  I would either have to duplicate the code
   for canvas (maintenance nightmare), or rewrite the other module to
   use a one-scrollbar canvas instead of a text window!
2) There could be a large number of these active at one time.  The
   text-based display function is barely fast enough as it is; any
   further slowdown would be unacceptable.
3) It just doesn't make sense to have to use what is essentially a
   graphical medium to display pure text.  If this is indeed necessary,
   then I would contend that there is a design problem here: an
   internal (inaccessible) dependence between packages.

>-Jim

______________________________________________________________________
Daniel A. Harling	uunet!pictel!harling		PictureTel, Inc.
Rockport, MA						Peabody, MA

	Opinions expressed herein are not necessarily those of
	PictureTel, Inc.; they are MINE, ALL MINE!  (So there.)
                                   ----  === ====