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From: tomt@maui.coral.COM (Tom Tulinsky)
Newsgroups: comp.windows.x
Subject: watch out for "negative" values in width or height to XDrawArc
Message-ID: <9008011420.AA21851@maui.coral.com>
Date: 1 Aug 90 14:20:21 GMT
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Lines: 27


I accidently passed a negative number into an unsigned that eventually
was passed to XDrawArc as the Height parameter.  The negative was
interpreted as a large positive (65527) and so no error message was
given, but my program slowed to a crawl (XDrawArc took about 15 sec.
of solid cpu processing to return; it also generated a massive amount
of paging).  I had to step through the drawing to find it.

This happened when I was zooming out some graphics, making them
smaller while subtracting some constants from them. Eventually the
scaled sizes were smaller than the constant and the result went
negative. Watch out...

I wouldn't be surprised if similar things happened to
XDraw/FillRectangle.


 Coral
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