[XeTeX] [tex-live] `BoldFont' feature for XeTeX?

[Jonathan Kew]

(This is a follow-up to a question originally asked on the tex-live  
list, but I am moving it to the XeTeX list as that's a better place  
for any further discussion.)

On 4 Mar 2008, at 9:35 pm, Jonathan Kew wrote:

> On 4 Mar 2008, at 7:39 am, Werner LEMBERG wrote:
>
>>
>> Jonathan,
>>
>>
>> I have been asked whether you can implement a `BoldFont' feature
>> similar to the `SlantFont' feature already part of XeTeX.  For CJK
>> fonts such an option can be very useful.  Currently, we are emulating
>> it with
>>
>>   \special{pdf: literal direct 0.5 w 2 Tr}
>>
>> but a native XeTeX solution would be better.
>
> I've avoided trying to implement a "synthetic bold" feature on the  
> grounds that it's likely to be far inferior to a true bold face.  
> While word processors and web browsers may get away with  
> algorithmically thickening strokes to create a "bold" effect, I  
> don't think it's something to encourage in quality typesetting.
>
> However, I can see that it could be useful at times, when there  
> aren't true styled fonts available; I'll try to look into the  
> possibilities.

I have just implemented a new "embolden" feature in xetex, which can  
be used to create "synthetic bold" fonts. For example:

   \font\A = "AR PL ZenKai Uni:script=hani" at 24pt
   \A 你好！\par
   \font\B = "AR PL ZenKai Uni:script=hani;embolden=2" at 24pt
   \B 你好！\par
   \end

Note that XeTeX will *not* automatically apply "embolden" in response  
to the /B option, if a true bold face isn't available; you'll only  
get "synthetic bold" if you explicitly ask for it. The amount of  
boldness is adjustable, and is in proportion to the font size.

This feature requires an update to the xdvipdfmx (or xdv2pdf) driver.  
As building xdvipdfmx "standalone" has always been a bit of a pain,  
I've put a copy of the sources into the xetex repository, and the  
build-xetex script there will now build the driver as well as xetex  
itself.

I hope a few people will try this out, and let me know of any  
problems before this is merged into the 2008 TeX Live release.

JK