Article View: comp.windows.interviews
Article #1173Re: drawing a circle
From: Dirk Grunwald
Date: Thu, 16 May 1991 21:01
Date: Thu, 16 May 1991 21:01
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>>>>> On 16 May 91 06:05:52 GMT, calder@uluru.stanford.edu (Paul Calder) said: PC> Dirk Grunwald asks ... PC> I can't seem to figure out the semantics of the 'curve' PC> Canvas call to draw a circle PC> There is no way to draw an exact circle using ordinary Bezier curves PC> (or any other polynomial parametric curves). In practice, however, -- Argle. I'm certain it says this somewhere in the numerous InterViews papers, but is there a reason that things like Circle/Ellipse & Arc aren't in the Canvas class? It would seem that these are fairly common graphics primitives, both in use and in implementation; e.g. via XDrawArcs in X, etc and they are typically efficient. Implementations that can't directly implement Arcs could have subclasses that use the bezier curves exactly as you desrcibe. But thanks for the answer, I'm off to implement pie charts. Dirk Grunwald -- Univ. of Colorado at Boulder (grunwald@foobar.colorado.edu) (grunwald@cs.colorado.edu)
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!swrinde!elroy.jpl.nasa.gov!ncar!csn!boulder!news!grunwald From: grunwald@foobar.colorado.edu (Dirk Grunwald) Newsgroups: comp.windows.interviews Subject: Re: drawing a circle Message-ID: <1991May16.210141.2470@colorado.edu> Date: 16 May 91 21:01:41 GMT References: <1991May15.184124.13302@colorado.edu> <CALDER.91May16000552@uluru.stanford.edu> Sender: news@colorado.edu (The Daily Planet) Reply-To: grunwald@foobar.colorado.edu Organization: University of Colorado at Boulder Lines: 26 In-Reply-To: calder@uluru.stanford.edu's message of 16 May 91 06:05:52 GMT Nntp-Posting-Host: foobar.colorado.edu