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From: norman@d.cs.okstate.edu (Norman Graham)
Newsgroups: comp.sys.mac.programmer
Subject: MacApp scrolling of indefinite sized views
Keywords: MacApp TScroller
Message-ID: <1991Apr2.233513.18137@d.cs.okstate.edu>
Date: 2 Apr 91 23:35:13 GMT
Sender: norman@d.cs.okstate.edu (Norman Graham)
Organization: Oklahoma State University, Stillwater
Lines: 26

I have a colleague that needs to provide a scrollable view for a
special kind of container object. This container object is unique
because it doesn't know how big it is or how many elements it contains, 
but it can return the element that is say 33% from the beginning
of the container. (When asking for an element based on a percentage,
the container can only take a guess which, in extreme circumstances,
can be way off.) The container also has a notion of a current element and
can get the previous, next, first, and last elements; so in theory
you could count all the elements, but in practice that would take far
too long.

My colleague would like to create a subclass of TScroller that can
scroll views of these container objects, but he can't find a class
definition that cleanly describes what he needs. In short, his definition
requires the scroller object to communicate directly with the container
object. The view that sits on the scroller object also communicates with
the container object (you would expect this). BTW, since the size of 
the container object is indefinite, the container view has to be either
the same size as the scroller or the maximum possible view size.

Would anyone care to enlighten us on how this should be done?
-- 
Norman Graham

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