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From: atoenne@julien.uucp (Andreas Toenne)
Newsgroups: comp.lang.smalltalk
Subject: Re: Bug with ST-80 on HP9000
Keywords: Smalltalk-80 rel. 4.0, HP 9000
Message-ID: <3191@laura.UUCP>
Date: 17 Apr 91 09:14:12 GMT
References: <1991Apr16.193604.399@vuse.vanderbilt.edu>
Sender: news@laura.UUCP
Organization: University of Dortmund, Germany
Lines: 24

In article <1991Apr16.193604.399@vuse.vanderbilt.edu> brian@vuse.vanderbilt.edu (Brian Antao) writes:
>Hi,
>	We have run into a bug while using Parcplace rel. 4.0
>smalltalk-80 running on the HP9000 -series workstations (330/350).
>The bug arises when using the message follow: while: on: ,
>usedn essentially to animate display stuff on a GraphicsContext.
>Using this message on the HP platforms causes a primitive error.
>This message works fine on the other platforms, 386 based machines,
>and Sun workstations. BTW, we running X11.
>Has anyone else encountered this problem, and know of possible
>fixes ?

I've found a bug in this method for images that were released last fall.
One of the two graphics contexts that are computed in follow:while:on:
was incorrect (in fact a Pixmap was built). Your follow:while:on: method
should contain the following two lines (opt. check the arguments to the
subsequent method moveTo:on:restoring:):
backGC := (aGraphicsContext paintBasis retainedMediumWithExtent: ext) graphicsContext.
scratchGC := (aGraphicsContext paintBasis retainedMediumWithExtent: ext * 2) graphicsContext.

	Good luck,

	Andreas Toenne
	atoenne@unido.uucp