[pstricks] Transparency issues with ghostscript

[Brandon Kuczenski]

Thanks, Herbert. In my case, I'm in a release hole because the old commands
got reinstated in gs 9.53, but 9.53 is not released to my distribution yet.

Just to be sure, it seems that the old commands are deprecated in 9.53 and
9.54, and may stop working thereafter:

For at least the next couple of releases (9.53/9.54), we will have
> Postscript procedures called .setopacityalpha and .setshapealpha whose
> implementation is a close approximation of what those operators previously
> did. Obviously, however, it would be preferable to remove those and have
> everyone use the correctly implemented and correctly named new operators.
>

-Brandon


On Thu, Jul 9, 2020 at 7:20 AM Herbert Voss <Herbert.Voss at fu-berlin.de>
wrote:

>
>
> Am 09.07.20 um 02:52 schrieb Brandon Kuczenski:
> > Hi folks,
> > I am trying to keep up with changes to ghostscript surrounding the
> > support of transparency operations.  Brief recap: starting with GS
> > 9.24, it was necessary to turn off "safer" mode in the ps2pdf step in
> > order to support transparency because of security issues:
> > vulnerabilities:
> > https://bugs.chromium.org/p/project-zero/issues/detail?id=1640
> > workaround:
> >
> http://tex.stackexchange.com/questions/453780/pgfs-and-pstrickss-opacity-is-not-working/453786
> >
> > Unfortunately, the Artifex team has now changed the transparency
> > implementation so that the ".setopacityalpha" and ".setshapealpha"
> > operators no longer work at all in 9.51 and 9.52. This means that
> > upstream code changes are required in order to continue to support
> > transparency.
> >
> > official notice:
> > https://ghostscript.com/pipermail/gs-devel/2020-May/010295.html
> > annoyed user's description (informative):
> >
> https://github.com/vectorgraphics/asymptote/issues/155#issuecomment-633202297
> >
> > For me, this meant that the old "-dNOSAFER" workaround was no longer
> > effective. Allegedly they will introduce backward compatibility in
> > 9.53? I don't quite understand. Anyway, I have fixed the problem by
> > downgrading to gs 9.27 but I wanted to check my understanding, make
> > sure this issue was being tracked, and see whether there is a plan to
> > fix it.
>
> the new option is -dALLOWPSTRANSPARENCY
>
> the following example works with gs9.53
> However you'll get a lot of warnings which are no problem, because
> PSTricks redefines the old shape commands for internal use
>
> Herbert
>
>
> \documentclass{article}
> \usepackage{pstricks}
> \begin{document}
>
> \begin{pspicture}[showgrid](-5,-5)(5,5)
> \psset{opacity=0.5}
> \pscircle*[linecolor=red](-2,-2){3}
> \pscircle*[linecolor=green](-2,2){3}
> \pscircle*[linecolor=blue](2,2){3}
> \pscircle*[linecolor=cyan](2,-2){3}
> \end{pspicture}
>
> \end{document}
>
>
> --
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