bug in quickdraw

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From: info-mac@uw-beaver (info-mac)
Newsgroups: fa.info-mac
Subject: bug in quickdraw
Message-ID:
Date: Thu, 5-Jul-84 13:49:37 EDT
Article-I.D.: uw-beaver>.1090
Posted: Thu Jul 5 13:49:37 1984
Date-Received: Fri, 6-Jul-84 01:09:52 EDT
Sender: daemon@uw-beave
Organization: U of Washington Computer Science
Lines: 36

From: Martin J Mahoney


While using the Mac yesterday i discovered a bug in Quickdraw.
I tried to draw two rectangles such that they shared a common side,
however, one was drawn using the FRAMERECT quickdraw routine and the
other used the LINETO quickdraw routines. When the two rectangles
were drawn the one draw using the LINETO calls had its vertical sides
slightly longer than the one drawn with the FRAMERECT call, when the
sides should have all been the same length.

Here is the code to reproduce the problem in both MS-basic and Forth:

MS-BASIC

10 dim rect%(3)
20 rect%(0)=50:rect%(1)=50:rect%(2)=100:rect%(3)=100
30 call FRAMERECT(varptr(rect%(0)))
40 call moveto(0,50):call lineto(0,100)
50 call lineto(50,100):call lineto(50,50):call lineto(0,50)
60 end


FORTH

gint
50 50 100 100 frame rectangle
0 50 0 100 vector
0 100 50 100 vector
50 100 50 50 vector
50 50 0 50 vector



Martin J. Mahoney
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