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- Path: sparky!uunet!usc!wupost!waikato.ac.nz!comp.vuw.ac.nz!actrix!David.Empson
- Newsgroups: comp.sys.apple2
- Subject: Re: List Manager Optimisations - Programmer - Help
- Message-ID: <1992Sep2.110542.26629@actrix.gen.nz>
- From: David.Empson@bbs.actrix.gen.nz
- Date: Wed, 2 Sep 1992 11:05:42 GMT
- Sender: David.Empson@actrix.gen.nz (David Empson)
- References: <1992Sep1.224906.11886@fawlty.towers.oz.au>
- Organization: Actrix Information Exchange
- Lines: 36
-
- In article <1992Sep1.224906.11886@fawlty.towers.oz.au> johnmac@fawlty.towers.oz.au (John MacLean) writes:
- > This is one for comp.sys.apple2.programmer :
- >
- > INFO:
- > [list manager just scrolls and redraws new items]
- >
- > PROBLEM:
- > I have a list box where this optimisation doesn't work (because each
- > list item is drawn with a custom "item draw" routine which modifies
- > the corresponding palettes - the scrolling does not scroll the palettes
- > of course, only the data).
- >
- > QUESTIONS:
- > I find it hard to believe that such an obvious problem has always been
- > in my software without anyone reporting it previously.
-
- According to the Toolbox ERS from the Golden Master CD-ROM (no, I
- don't have the System 6 Programmers Reference, yet...), the list
- manager doesn't bother to call the draw routine for list members that
- will be completely clipped.
-
- Before doing this, it calls ScrollRect to scroll the list to its new
- position (see IIgs Technical Note #74). Prior to System 6, the
- listDraw routine was called for all members INCLUDING those which had
- scrolled. This is no longer done - system 6 only calls listDraw for
- the newly visible items.
-
-
- You might be able to get around it by invalidating the entire list
- rectangle, forcing all items to be redrawn. You would need to trigger
- this whenever the list was scrolled, and it would look ugly!
- --
- David Empson
-
- Internet: David.Empson@bbs.actrix.gen.nz EMPSON_D@kosmos.wcc.govt.nz
- Snail mail: P.O. Box 27-103, Wellington, New Zealand
-