# [NTG-pdftex] images in formats

Martin Schröder martin at oneiros.de
Wed Jun 27 14:22:36 CEST 2007

2007/6/27, David Kastrup <dak at gnu.org>:
> For example, preview-latex uses mylatex.ltx to dump the state of the
> TeX at \begin{document} time.  Not allowing any image references (like
> in \savebox commands) before that point of time is a rather brutal
> restriction.

Why do you need it and what do you gain by using \savebox? The speed
increase is most likely minimal and the document needs to read the
image anyway -- unless you want to dump fragments of pdf code into the
format. If we expanded the dvi model we would dump the meta
information about pdf things and then undump them later. This needs
code for dumping and undumping this meta information. And
\immediate\pdfximage would still fail.

> Again: the \AtBeginDvi command was added to LaTeX precisely in order
> to conserve pretypeset stuff that would otherwise get lost at a format
> dump.

So store the commands there. Do you really need their expansion?

Don't forget: pdfTeX is one-pass, while TeX->dvips is two-pass.

Best
Martin