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From: Peter_King@NeXT.COM (Peter King)
Newsgroups: comp.sys.next
Subject: Re: How do you draw lines into the current view for Rubberbanding
Message-ID: <878@rosie.NeXT.COM>
Date: 31 May 91 20:46:04 GMT
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In article <4043@ssc-bee.ssc-vax.UUCP> dmg@ssc-vax (David M Geary) writes:
> 
>   If all you want to do is rubber-banding without the flicker, why allocate  
an
> off-screen buffer for the *entire* window?  Instead, why not allocate 4  
buffers,each of which is one pixel wide by screen width (or height) long:
> 

This is really an extension of the double-buffered compositing I was talking  
about earlier, but you're being much smarter about choosing which background  
pixels to retain.  Would you call this quadruple buffering??? :-)

The mechanism I suggested (buffering the whole window) works well when the  
dynamic drawing you're doing isn't a simple rubber-band.  For example, you  
might be doing a draw program and you want to drag out a filled rectangle.   
This could potentially cover the whole window.

But, as you say, if you are doing a simple rubber-band, four one-pixel-wide  
buffers work really well.

Peter


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