[luatex] Bug: When nesting Form XObject reference in <box>, \pdfxform resources {<resources>} <box> -> missing user-provided <resources>

[luigi scarso]

On Mon, Mar 19, 2018 at 1:29 PM, Alexander Grahn <A.Grahn at hzdr.de> wrote:
> On Mon, Mar 19, 2018 at 01:17:11PM +0100, Hans Hagen wrote:
>>On 3/19/2018 12:58 PM, Alexander Grahn wrote:
>>> On 3/19/2018 11:52 AM, Hans Hagen wrote:
>>>> On 3/19/2018 11:20 AM, Alexander Grahn wrote:
>>>>> Dear all,
>>>>>
>>>>> it seems that I discovered a bug in connection with nested Form XObjects
>>>>> (pdftex built-in \pdfxform) that occurs in pdfTeX as well as in LuaTeX.
>>>>>
>>>>> The \pdfxform built-in provides the optional `resources {<resources>}'
>>>>> argument, as in
>>>>>
>>>>>     \pdfxform resources {<resources>} <box>
>>>>>
>>>>> , in order to allow the user to insert additional entries in the /Resources
>>>>> dictionary of the Form XObject to be produced from box register <box>.
>>>>>
>>>>> This works as advertised for ordinary box content (1st \pdfxform in the code
>>>>> below), but as soon as another Form XObject is referenced inside <box>, the
>>>>> `resources {...}' argument is ignored and user-provided <resources> are missing
>>>>> in the generated PDF code (2nd \pdfxform).
>>>>>
>>>>> Here is a minimal example for pdfTeX and LuaTeX for demonstration. The PDF
>>>>> object numbers mentioned in the comments are different in the PDF output from
>>>>> LuaTeX.
>>>>>
>>>>> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>>>>> % Bug: When nesting Form XObject reference in <box>,
>>>>> %      \pdfxform resources {<resources>} <box>
>>>>> %      --> missing user-provided <resources>
>>>>>
>>>>> \input luatex85.sty
>>>>>
>>>>> \pdfcompresslevel=0
>>>>> \pdfobjcompresslevel=0
>>>>>
>>>>> \setbox0=\hbox{World}
>>>>> \edef\wrldwd{\the\wd0}
>>>>>
>>>>> \pdfxform
>>>>> attr {}
>>>>> resources {/Properties <</Key1 (Val1)>>} % OK
>>>>> 0
>>>>>
>>>>> %nesting Form XObject reference
>>>>> \setbox0=\hbox{Hello \hbox to \wrldwd {\pdfrefxform\pdflastxform\hss}!}
>>>>>
>>>>> \pdfxform
>>>>> attr {}
>>>>> % /Properties <<...>> missing in /Resources dict (object `8 0'), ref'ed in
>>>>> resources {/Properties <</Key2 (Val2)>>}%       Form XObject (object `2 0')
>>>>> 0
>>>>>
>>>>> \pdfrefxform\pdflastxform
>>>>>
>>>>> \bye
>>>>> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>>>>
>>>> there is no nesting stack kept there ...
>>>>
>>>> \immediate\pdfxform ...
>>>>
>>>> works ok
>>>>
>>>> Hans
>>>
>>> That is strange, as for `attr {...}' such a stack apparently exists.
>>> `resources {...}' should behave in the same way.
>>
>>resources are more complex as they also need to merge with others ...
>>it's something we will ook into but don't expect changes too soon as
>>we're in texlive code freeze mode
>
> Thank you, Hans, a lot for taking this into consideration!
>
> Kind regards,
> Alexander

pdftex in TeX Live 2018 has a patch,
but currently we need to test luatex a bit more,
so it's not sure that the patch will be committed for  luatex in TeX
Live 2018 too.
It will be for sure in the next 1.08.0 after texlive and just before
the context meeting in September.

-- 
luigi