[comp.sys.next] Window Refreshing

ali@polya.Stanford.EDU (Ali T. Ozer) (12/23/88)

In article <5567@cbmvax.UUCP> daveh@cbmvax.UUCP (Dave Haynie) writes:
>Aargh!! No, no!  Please don't say that this system doesn't support "SMART" 
>refresh windows!  This is supposed to be a "real" computer with lots of
>memory.  If the application doesn't know how to refresh a window, it
>shouldn't have to.  Let the OS handle all aspects of a window.  Just cause
>the Mac doesn't (or didn't, maybe it does now?) handle such things doesn't
>mean the rest of the world should stay so barbaric.  
>Dave Haynie  "The 32 Bit Guy"     Commodore-Amiga  "The Crew That Never Rests"

Don't panic! NextStep does support smart-refresh windows, and almost all 
applications use them. There are actually three types of refreshing:
  
   NONRETAINED, where windows are told to redraw parts of themselves 
	     whenever necessary.
   RETAINED, where covered parts of the window are stored in a backup area.
   BUFFERED, like retained, except all drawing goes to the backup area and
	     has to be explicitly flushed by the programmer. This allows
	     a simple way to double-buffer.

Turns out that instead of just saving the covered parts of a window, the
RETAINED mode just keeps a buffer as large as the window in the background.
This eliminates the problem of having to alloc/dealloc many small pieces
of backup storage for a window as another is dragged in front of it.
Otherwise, though, this mode is equivalent to Amiga's SMART_REFRESH, from
a programming standpoint --- the programmer doesn't have to do any work 
for assuring consistency of window contents.

Ali Ozer, NeXT Developer Support
aozer@NeXT.com

herrmann@hpbblb.HP.COM (Andreas Herrmann) (01/05/89)

>   Oh well, time to hit the bookstore for a good book on Objective C.
> Suggestions, anyone?

Try Brad Cox' 'Object Oriented Programming' (Addison Wesley 1988, 
I believe). He's one of the inventors of Objective-C and cofounder
of StepStone Inc. (which used to be PPI).
Some people may find the book rather verbose but it gives a general 
introduction to OOP as well as an overview of Objective-C. 
Besides, it's still the only book on the language as far as I know.

Andreas Herrmann (ah@hpbbn)
Hewlett-Packard GmbH, FTZ1
Boeblingen, West Germany

johnl@ima.ima.isc.com (John R. Levine) (01/08/89)

In article <6860001@hpbblb.HP.COM> herrmann@hpbblb.HP.COM (Andreas Herrmann) writes:
>
>>   Oh well, time to hit the bookstore for a good book on Objective C.
>> Suggestions, anyone?
>
>Try Brad Cox' 'Object Oriented Programming' (Addison Wesley ...

It's actually "Object-Oriented Programming: an Evolutionary Approach,"
Addison-Wesley, 1986.  Get the corrected 1987 edition. ISBN 0-201-10393-1.

The book would have benefitted a great deal from some serious editing but
even so it does a decent job of introducing OOP in general and Objective C
in specific.  The language on the NeXT is a little different from that
described in the book, but not enough to cause much confusion.
-- 
John R. Levine, Segue Software, POB 349, Cambridge MA 02238, +1 617 492 3869
{ bbn | spdcc | decvax | harvard | yale }!ima!johnl, Levine@YALE.something
You're never too old to have a happy childhood.