[XeTeX] Re: [OS X TeX] pdftex's "hz extensions"

[Bruno Voisin]

Le 15 nov. 04, à 14:40, Jonathan Kew a écrit :

> I suspect that people are often loading fonts in XeTeX where the 
> height and depth (as measured by XeTeX, not true character bounding 
> boxes) comes close to, or even exceeds, the default \baselineskip 
> you're using, and so \lineskip kicks in; and then as soon as any 
> character is offset vertically, you'll see disturbance of the line 
> spacing.

I think that's indeed what's happening. Here are two examples. First 
the output of pdfTeX, with Lucida fonts:

-------------- next part --------------
A non-text attachment was scrubbed...
Name: Image 2.pdf
Type: application/pdf
Size: 43217 bytes
Desc: not available
Url : http://tug.org/pipermail/xetex/attachments/20041115/003a4550/Image2-0001.pdf
-------------- next part --------------


and

-------------- next part --------------
A non-text attachment was scrubbed...
Name: Image 4.pdf
Type: application/pdf
Size: 31441 bytes
Desc: not available
Url : http://tug.org/pipermail/xetex/attachments/20041115/003a4550/Image4-0001.pdf
-------------- next part --------------


Now the same input in XeTeX, with mixture of Lucida and Hoefler Text 
for maths:

-------------- next part --------------
A non-text attachment was scrubbed...
Name: Image 1.pdf
Type: application/pdf
Size: 47666 bytes
Desc: not available
Url : http://tug.org/pipermail/xetex/attachments/20041115/003a4550/Image1-0001.pdf
-------------- next part --------------


and

-------------- next part --------------
A non-text attachment was scrubbed...
Name: Image 3.pdf
Type: application/pdf
Size: 33671 bytes
Desc: not available
Url : http://tug.org/pipermail/xetex/attachments/20041115/003a4550/Image3-0001.pdf
-------------- next part --------------


In both examples in XeTeX, Hoefler Text is used (intentionally) for the 
superscripts.

> Well, that's not quite how XeTeX works, but I am aware this is an 
> issue. (One possibility I'm considering is to try supporting true 
> character bounding boxes, but it would come at a performance cost and 
> so would be an optional setting.)

That would be nice (at some point in the future, I understand you're 
quite busy), if that would mean emulating, for AAT (and OpenType) fonts 
what TeX does for MF fonts (such as CM etc.).

Bruno