[pstricks] Transparency issues with ghostscript

[Herbert Voss]

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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