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From: batcheldern@hannah.enet.dec.com (Ned Batchelder)
Newsgroups: comp.lang.postscript
Subject: Re: Advice sought: drawing boxes faster
Message-ID: <7513@shlump.nac.dec.com>
Date: 16 Jan 90 20:19:54 GMT
References: <2733@draken.nada.kth.se> <50851@bbn.COM>
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Reply-To: BatchelderN@hannah.enet.dec.com
Organization: Digital Equipment Corporation
Lines: 20

You've gotten some good suggestions.

The "image" idea is probably the biggest win, but only works if your squares
really do line up properly. If they have to overlap each other, or if the 
result is sparse in some way, it may not be the best way to go.

If the data doesn't lend itself to "image"ing for some reason, then a font is
the right way to go. But, you can't create a font with each character a
different shade of gray as suggested. The font cache only remembers shapes,
not shades. So your best bet is a font with different sizes and shapes of 
boxes, like your idea of run length encoding. You then have to set the gray
explicitly.

With text, the way to go fast is to get as much done with each "show" as
possible. So if you need to do a mix of two grays, you might be better off
doing one string that is all of the light gray, with spaces for the dark, and
then another that is all the dark with spaces for the light, and they'll
mesh together on the page.

Ned Batchelder, Digital Equipment Corp., BatchelderN@Hannah.enet.DEC.com