[Dev-luatex] Q: Can LuaTeX produce xdv?

Jonathan Fine jfine at pytex.org
Thu Jan 1 23:09:33 CET 2009


Yannis Haralambous wrote:

> the original DVI format already supports 4-byte character, what more 
> Unicode-savviness do you need? Of course one should decide whether DVI 
> should contain glyph indexes or Unicode codepoints.

I'd like bidirectional information to be available.

> Unless you mean by Unicode-savviness that one should have both glyph 
> indexes and Unicode codepoints (I think that's what XeTeX is doing). A 
> very bad approach since character and glyph correspondances are 
> many-to-many.
> 
> On the other hand, if we use just glyph indexes in the DVI file then we 
> can hardly do anything with it than print it (going to PDF will be 
> difficult since the correspondance with characters is lost).

Thank you for this, Yannis.

What I want is for LuaTeX and XeTeX to have a shared 'extended dvi 
format' which is suitable for print, for generating PDF and possibly 
other purposes.

And of course I'd like this format to be of at least satisfactory 
technical quality.

My (inexpert) understanding is that the Unicode code-point to glyph 
index mapping is a property of the font:
    http://www.microsoft.com/typography/otspec/cmap.htm

Yannis:  I admire both yourself and Jonathan Kew as experts in fonts, 
and so it worries me that you say that XeTeX is adopting a "very bad 
approach".

I'm copying this to Jonathan Kew.

-- 
Jonathan


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