Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!SUN.COM!parcplace!aladdin!ghost
From: parcplace!aladdin!ghost@SUN.COM (L. Peter Deutsch)
Newsgroups: gnu.ghostscript.bug
Subject: bug in 'scale' operator
Message-ID: <8903272257.0.UUL1.3#5127@aladdin.UUCP>
Date: 28 Mar 89 05:57:30 GMT
Sender: daemon@tut.cis.ohio-state.edu
Distribution: gnu
Organization: GNUs Not Usenet
Lines: 21

There is a bug in the 'scale' operator that manifests itself only
when scaling in a rotated or skewed coordinate system.  The fix is to
replace the indicated two lines of the gs_scale procedure in
gscoord.c:

int
gs_scale(gs_state *pgs, floatp sx, floatp sy)
{	pgs->ctm.xx *= sx;
!	pgs->ctm.xy *= sx;
!	pgs->ctm.yx *= sy;
	pgs->ctm.yy *= sy;
...etc...

Thanks to Lou Katz for contributing the test case (the SIGGRAPH logo)
that uncovered this.

		- P. D.

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