l3backend: adding new DVI specials?
joseph.wright at morningstar2.co.uk
Thu Feb 13 08:54:30 CET 2020
On 13/02/2020 04:26, Norbert Preining wrote:
> Hi all,
> the recent update of the l3 packages changed something with the DVI
> specials. pyxplot suddently gives warnings about unhandled DVI specials:
> is this a known change and to be expected?
A while ago now we added some code to l3backend to start to address 'out
of the box' PDF feature handling. That's for stuff like hyperlinks,
color, etc. In DVI mode, one needs stuff adding to the PostScript
header. (At present not all of this is 'live', in particular link breaking.)
Initially, we simply added everything as \special lines directly
containing the PostScript, but that leads to warnings with dvipdfmx if
the right backend isn't selected. It also meant there was lots of
material in the \showbox output. Moving it to a .pro file meant that
inclusion used only one line
and this line is simply ignored by dvipdfmx. We realised that other
systems might not know this one line, but felt that it was hopefully
possible that a similar '"skip header=" lines' might be added to any
cases. The one we had in mind was dvisvgm: I'm not familiar with pyxplot.
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