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From: shatara@memit.dec.com (Chris: 223-8753, TECHNOLOGY OFFICE, MLO1-4/T35)
Newsgroups: comp.sys.apple
Subject: RE: 2 more //gs programming questions
Message-ID: <8907011229.AA12157@decwrl.dec.com>
Date: 1 Jul 89 15:29:00 GMT
Organization: Digital Equipment Corporation
Lines: 38

re Note from Dave Lyons

>>You can use GetPortRect to find out which part of the window you're scrolled
>>to, or you can get the bounding box of the update region.  More details on
>>request--gotta take off!
> 
>Let me try this once more, not under time pressure this time.
> 
>Inside your content-draw routine, BeginUpdate has already been called by the
>system, so what you want to do is get the bouding box of the VisRegion (try
>GetVisHandle()^^.bBox to get the smallest rectangle that encloses the part of
>the window that needs to be updated.
> 

Dave, you cought my interest on this one! As usual I have several 
questions as I tried implementing this and it didn't quite work as I would 
have expected it to.


1. I am assuming that the Window Definition Procedure pointed to by
   wContDefProc is used for updating the window contents as well as
   drawing them for the first time.

2. Your statement above implies that BeginUpdate (and hence EndUpdate) has
   has already been called when I unter the Window Def Procedure after an
   update event. Is this true.

3. re 1. above, when the window is first created on the desktop, calling
   GetVisHandle()^^.bBOX will yield a rectangle of what size?  ..I would 
   expect (hope) the size of the content region.

4. How does GetVIsHandle differentiate from the region needing to be 
   updated on the mainscreen and a region of a window on the screen.


Happy Forth!

Regards, chris Shatara