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

Jonathan Fine jfine at pytex.org
Sun Jan 4 09:13:07 CET 2009


Martin Schröder wrote:
> 2009/1/2 Jonathan Fine <jfine at pytex.org>:
>> Please could I be told, what are the main benefits of directly producing
>> PDF?
> 
> Reasoning about and manipulating included PDFs. This is much harder
> with a two-pass engine like XeTeX + postprocessor; as an example
> compare the knowledge of XeTeX (the program) and pdfTeX about included
> PDFs.

I'm sorry, but I don't understand.

Yes, typesetting applications need to know about included objects such 
as images (and fonts).  But from there you conclude that there's a 
benefit in generating PDF directly.  I don't see how this follows.

I'll invent an example (so it's not really an example).  We wish to 
resize an image to fit the measure, but if it's a bitmap image we want 
to  choose a scaling factor that works well with our planned output 
device.  Here's another.  We want to know if the image contains colour, 
because if it does it should appear in the colour plates section.

In both cases we have to open the image file and, as you say, reason 
about it.  Based on this reasoning we come to a conclusion (such as a 
scale factor) and both 9a) typeset the text and (b) process the image 
accordingly.

LuaTeX does (a) and (b) at the same time.  I see no reason why a 
'special' that says 'do (b)' should not be written to the xdv or 
whatever output file.

[Discussion of performance snipped]

> But as I said: Show us your code.

Well, it's not MY code, but I'm sure you're welcome to use it:
    http://scripts.sil.org/svn-public/xetex/TRUNK/
    http://scripts.sil.org/svn-public/xdvipdfmx/TRUNK/

XeTeX is distributed under the X11 free software license.

-- 
Jonathan


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