Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!bbn!apple!AppleLink.Apple.Com!Marriott1
From: Marriott1@AppleLink.Apple.Com (Greggy)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Saving area under dialog boxes (Re: WingZ)
Message-ID: <1604@internal.Apple.COM>
Date: 29 Apr 89 22:20:18 GMT
References: <2993@tank.uchicago.edu>
Sender: usenet@Apple.COM
Distribution: na
Organization: Apple Computer, Inc.
Lines: 39

In article <2993@tank.uchicago.edu> ra_robert@gsbacd.uchicago.edu writes:
> What about in a paint type program?  I've been working on one, and when 
someone
> "draws" on the screen I first draw it on the screen (e.g. on the 
simplest level
> with calls such as LineTo)  and then blit it to my offscreen buffer 
(from which
> I refresh my image) for permanent storage when the drawn object is done 
(i.e,
> on MouseUp).  Wouldn't there be times when you need to CopyBits from 
screen
> memory to your offscreen buffer?  I suppose one _could_ draw to your 
offscreen
> bugger and CopyBits it on screen constantly, but that sounds fairly 
awful in
> terms of speed, etc.

Microsoft Word caches its data this way when it scrolls.  The result is 
that if you have a floating window (such as Overtime, a clock that always 
floats above everything else), then it also gets cached!  When you scroll 
back down, you get old images of the clock.

Keeping an offscreen image to blit from still seems like the best idea to 
me.

> Robert
> ------
> ra_robert@gsbacd.uchicago.edu
> ------

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ Greg Marriott               +                      AppleLink: Marriott1 +
+ Just Some Guy               +                                           +
+ "My phone is always busy"   +   Internet: Marriott1@AppleLink.Apple.Com +
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ Just in case disclaimers mean anything at all:                          +
+    What I say comes from my own twisted perception of the world         +
+    and does not represent the policy or opinion of Apple Computer, Inc. +
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++