[luatex] LuaTeX warning: Misplaced \pdfrestore by (983040sp, 0sp)

[Heiko Oberdiek]

On 25.04.2013 22:08, Patrick Gundlach wrote:
> Hello Heiko,
> 
>>> when running the following code, I have a problem that subsequent
>>> boxes are misplaced. A warning is issued:
>>>
>>> LuaTeX warning: Misplaced \pdfrestore by (983040sp, 0sp)
>>>
>>> What am I doing wrong?
> 
> 
>> There are two different coordinate
>> systems: PDF and TeX, \pdfrestore restores the graphics state including
>> the current transfer matrix to the state of \pdfsave in the PDF
>> coordinate system. But if the TeX position has moved away, the
>> two coordinate systems are out of sync. Therefore you get a warning
>> that you might shoot yourself in the foot.
> 
> I my case, I did get garbled output, so the warning was very good.
> 
> Thanks for your comment. This is what I have now:
> 
> local function scalebox(scalefactor,box)
>     local pdf_save, pdf_restore, pdf_setmatrix
>     pdf_save = node.new("whatsit","pdf_save")
>     pdf_restore = node.new("whatsit","pdf_restore")
>     pdf_setmatrix = node.new("whatsit","pdf_setmatrix")
>     pdf_setmatrix.data=string.format("%.4g 0 0
> %.4g",scalefactor,scalefactor)

"%.4g" allows the "e style", you get invalid PDF, if scalefactor
is equal smaller than 0.000099995 (e.g. 0,00009 => 9e-05) or
equal/greater than 9999.5 (e.g. 10000 => 1e+04).
PDF numbers must not be given in exponential notation.

>     local hbox = node.hpack(box)
>     hbox = node.insert_before(hbox,hbox,pdf_setmatrix)
>     hbox = node.insert_before(hbox,pdf_setmatrix,pdf_save)
> 
>     hbox = node.hpack(hbox)
>     hbox.height = box.height * scalefactor
>     hbox.width = box.width * scalefactor
>     hbox.depth = 0
>     node.insert_after(hbox,node.tail(hbox),pdf_restore)
> 
>     local newbox = node.vpack(hbox)
>     return newbox
> end
> 
> which seems to work because the box doesn't have any depth.

The original box might have a depth. The other parameters (width and
height) are recalculated, but the depth is set to zero?

The graphics package uses something like:

  \setbox0=\hbox{<user box content>}
  \setbox2=\hbox{%
    \pdfsave
    \pdfsetmatrix...
    \hbox to 0pt{%
      \copy0
      \hss
    }%
    \pdfrestore
  }
  \wd2=<scale factor>\wd0
  \box2

Yours sincerely
  Heiko Oberdiek