Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!tut.cis.ohio-state.edu!snorkelwacker!bloom-beacon!EXPO.LCS.MIT.EDU!rws
From: rws@EXPO.LCS.MIT.EDU (Bob Scheifler)
Newsgroups: comp.windows.x
Subject: Re: Querying pixels
Message-ID: <8912282127.AA13896@expire.lcs.mit.edu>
Date: 28 Dec 89 21:27:18 GMT
References: <2576@cunixc.cc.columbia.edu>
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Lines: 16


    I thought I would use the pixels to keep
    track of what I have already filled in. The problem is, I can't figure
    out how to query a pixel.

Any algorithm which depends on reading pixel data back from the server
is a bad algorithm.  It is horribly expensive to do round-trips to the
server like this, particularly for individual pixels.  Also, if you
are trying to read from a window, you have no guarantee of getting
correct data (due to being obscured by other windows, with no guarantee
of backing store).  So, although I could tell you how to query a pixel,
you're better off not knowing. :-)

    If this is the wrong forum on which to ask such a question,

It's exactly the right place to ask such a question.