[luatex] dump a tfm to a file

[Ulrike Fischer]

Am Tue, 21 Jun 2011 14:09:04 -0500 schrieb Luis Rivera:

>>> tex4ht doesn't use only this htf-files. At first it loads the tfm's
>>> of the fonts mentioned in the dvi (I don't know exactly why).
>>
>> If it really needs TFMs, I do not think it can ever be compatible with
>> luatex (or xetex, for that matter).
>>
> 
> afaik, tex4ht doesn't load the tfms to generate the dvi: that's
> required by some tex engine (pdfTeX, afaik) which generates a dvi with
> some tailored suited macros (it makes three passes, to ensure the bbl,
> idx and other stuff are properly compiled); then, in the second stage,
> tex4ht deciphers the dvi with the htf files to generate some xml
> files; and in the third stage, t4ht assembles the final html/odt file
> with the xmls, the images, and all the other stuff generated by the
> previous steps. I collect that from reading the oolatex script, which
> actually controls the whole process.
> 



To avoid some confusion: There is tex4ht as "system", large package
with various files, folders, configuration etc. And there is the
central application tex4ht.exe. 

tex4ht.exe is a dvi-driver. It takes a dvi and generates eg a
html-file. To be able to do this the dvi must contain a lot
\specials. This specials are inserted by tex4ht.sty and various
4ht-files during the previous (lua)latex runs.  


> So, in my not very enlightened opinion, htf files are necessary only
> because the tfm files that generate a dvi may have different
> encodings, so the resulting dvi files are spaghetti encoded, and there
> is some need to ensure that appropriate utf8 sequences are produced
> from the messy dvi into the the generated xml files. htf files are
> mainly maps from 8 bit encoded fonts into utf8.
> 
> If a TeX engine could read and write files properly UTF8 encoded, the
> need for htf files would be bypassed; tex4ht would only have to
> translate typesetting instructions (from a target successor of dvi
> format) into xml tags, since the encoding would be UTF8 right from the
> beginning.

The htf-files don't do only reencoding or mapping. They are used to
control the "look" of the output. E.g. 

'b' ''     98 

will give the expected "b" if the input is char98 (= b). But in
another htf-file you find at position 98 this:

'B' '4'    98

and this will give 

<span class="small-caps">B</span>

(The <span>  comes from the '4' which is a class number). 

So the htf-files gives you a low-level mapping characters to other
representations (like html entities) and of fonts to font features
in html like small-caps, bold etc. 


The generation of the dvi works fine with luatex. The problems
starts at the dvi -> html step with tex4ht (if the document uses
system fonts). The dvi contains font names like "file:lm-modern..."
and tex4ht looks (for still unknown reasons) for its tfm and can't
find it. 

For a simple document I got around the problem by using the
low-level command \font\test=Arial and renaming an arbitrary tfm to
arial.tfm.  Currently I seem to be able to use ASCII and öäü, but
the € is output to  ÿ. This looks like a 256-barrier ;-(. But
perhaps one can get around it by extending the htf-files.



-- 
Ulrike Fischer