[XeTeX] XeTeXpdffile positions differently on MacOS and Linux

[Paul Howson]

On 16/05/2008, at 10:39 PM, Jonathan Kew wrote:

> This is a xetex problem; the issue shows up when the crop-box of the
> PDF has very large coordinates (around 7200pt in your case) rather
> than being close to the origin. In this situation, a discrepancy
> between how the Linux and Mac versions deal with the coordinates (and
> the slight difference between TeX and PostScript units) becomes
> clearly visible. The difference between a "point" of 1/72 inch and
> one of 1/72.27 inch, when multiplied by 7200, leads to an offset of
> about 9.5mm... exactly what you're seeing.
>
> I have just made some corrections in the xetex svn source (version
> 0.998.5-dev), and with this latest version I am seeing consistent
> behavior across the platforms. Unfortunately, this does mean that
> when you update to TeX Live 2008 (or another release that includes
> the fix) you will need to adjust your document to remove the
> "compensating" kerns you currently have in the OS X version.
>
> (Most people will be unaffected; it's the huge coordinates involved
> in your cropped PDF from Illustrator that make the discrepancy  
> visible.)

Jonathon,

Thank you so much for spending the time to track this down. You are a  
champion.

This surely must qualify for the obscure bug of the year award? :)

I'm puzzled why Illustrator uses such enormous coordinates for the  
crop-box. Presumably it uses the same coordinate system for all the  
"boxes" -- bounding, art, etc.

But why this range of values?

OK, now I see. The "artboard" size for the document is 5080mm square.  
That is 14400 points! And because the tiny little graphic is right in  
the middle of the artboard, it would have a coordinate of 7200 points.  
Interesting.

If I set the artboard size to 10mm x 10mm then the cropbox coordinates  
are around 7-20pt -- 1000 times less! And now the MacOS version of the  
page renders correctly with the Linux settings.

Well I never.

Anyway, now I know how to workaround this -- just set the artboard  
size as small as possible.

Paul Howson