# [NTG-context] Disable reuse of figures

Hans Hagen j.hagen at xs4all.nl
Sat Feb 19 11:26:56 CET 2022

On 2/19/2022 7:30 AM, Aditya Mahajan via ntg-context wrote:
> Hi,
>
> This is related to a bug report for the filter module:
>
> Normally, when the same figure is included twice, context only includes the figure once and refers to the included figure the second time. The option object=no to externalfigure is supposed to prevent that, but it doesn't work. For example, consider the following example the bug-report uses graphviz as the external program, but I have changed that to context to keep things self contained)
>
> \usemodule[filter]
>
> \defineexternalfilter
>    [graphviz]
>    [
>      filter=context --purge,
>      output=\externalfilterbasefile.pdf,
>    ]
>
>      {\externalfigure[#1][object=no]}
>
> \starttext
>
>    Circle:
>    \startgraphviz
>      \startMPpage
>        draw fullcircle scaled 1cm;
>      \stopMPpage
>    \stopgraphviz
>
>    Square:
>    \startgraphviz
>      \startMPpage
>        draw fullsquare scaled 1cm;
>      \stopMPpage
>    \stopgraphviz
>
> \stoptext
>
> Behind the scenes, the first \startgraphviz ... \stopgraphviz environment writes the content to an external file (\jobname-temp-graphviz.tmp), runs context --purge \jobname-temp-graphviz.tmp, which creates \jobname-temp-graphviz.pdf. The \ReadPDF macro then includees the file (with object=no).
>
> At the next \startgraphviz .. \stopgraphviz, the same process is repeated. The \jobname-temp-graphviz.pdf file is overwritten and the new file should have been included. But it is not. The output contains the first image twice.
>
> I thought that object=no should have prevented the reuse. In fact, if I compile the file with luatex, I get an error message:
>
> ! error:  (pdf inclusion): file has changed '12-two-outputs-temp-graphviz.pdf'
> mtx-context     | fatal error: return code: 256
>
> Any idea why object=no is not working?
the pdf file is kept open, for various reasons:

- performance
- the might be different pages to fetch
- analysis happens when the image is placed, inclusion happens later

so you try to reopen an already open file (which has not been completely
processed)

Hans

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