[XeTeX] combining overline and other unicode features
Jonathan Kew
jonathan_kew at sil.org
Sat Jun 25 18:29:50 CEST 2005
On 25 Jun 2005, at 4:21 pm, Bernd wrote:
> Hello,
> I've been playing around with the transliteration of Arabic using
> Unicode Characters. I found out that combining characters for dots
> and bars exist but I have no idea how to apply them. They copy fine
> from other texts but how do I type these myself? Is there a
> combination I have to enter on my keyboard as you do with accents
> and graves on vowels? Or do I need to enter the unicode number plus
> the letter?
It depends on the keyboard layout you're using, and what characters
that is able to generate. The standard US layout doesn't provide
keystrokes for these, but others might. Besides the layouts that ship
with the OS, there are links to some other available layouts,
including some intended for phonetic transcription, at:
http://scripts.sil.org/inputresources
If no available layout is suitable for your needs, there are several
utilities to help you build your own custom layout. One you could try
is Ukelele:
http://scripts.sil.org/ukelele
Alternatively, you can enter any Unicode character using the Hex
Input layout that Apple provides (and which you can enable via the
International preference panel); using this, you can type a 4-digit
Unicode value (in hex) while holding down the Option key, to generate
a single character. So <Option-0-3-0-4> gives the combining macron
(bar) above a letter, for example.
Or you can encode the characters in your TeX source using the
^^^^xxxx notation (four ^ characters, followed by four lowercase hex
digits); so ^^^^0304 also represents the combining macron.
Note that how well these combining characters work depends whether
the font you're using has full support for placing them properly over
the base characters; with many fonts, you may not get good
positioning. One that should support most combinations well is Doulos
SIL:
http://scripts.sil.org/doulossilfont
With many fonts, you'll get better results if you use precomposed
Unicode characters that represent the base letter + diacritic as a
single code, for the cases where these are available in Unicode.
That's what the standard keyboard layouts generate when you use "dead-
keys" to apply accents like acute/grave; they don't use the
individual combining marks, as relatively few fonts support these
fully. A tool like Ukelele would allow you to create a keyboard with
additional dead-keys for the precomposed accented characters you want
to use.
Hope this is helpful,
JK
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