[XeTeX] [off-topic] proper OpenType tag for hanging diacritics

[Andrew Moschou]

This solution reminded me of the hanging punctuation example in Appendix D
of the TeXBook. Here, Knuth describes a method to protrude the punctuation
characters into the margin using positive and negative kerns. In the middle
of a line, the two kerns cancel each other out (so there is no change) but
at the end of the line, one of the kerns is removed, so the other
effectively pulls the punctuation symbol into the margin. By applying the
method to the appropriate accented Greek capitals, instead of punctuation, a
similar effect to varying degrees can be achieved (The positive kern might
have to be larger than the negative kern to counter the negative left
bearing of the glyph).

Andrew



2009/10/6 John Was <john.was at ntlworld.com>

> Hello Pablo
>
> Until this can be fixed properly from within the font itself, you might try
> the following approach (this takes as its example Unicode character 1F1D,
> viz. asper acute in front of capital epsilon):
>
>
> \catcode"1F1D=\active
>
> \def Ἕ{\leavevmode \hbox to 0.2em{\hfill \char"1FDE\hfill}\char"0395}
>
>
>
> Then every time you have Ἕ in your file XeTeX will typeset the
> free-standing asper+lenis character (Unicode 1FDE) followed by a capital
> epsilon (Unicode 0395).  I have given a 0.2em box but you could try
> narrowing this down to the minimum that will work without generating an
> overfull \hbox (this is likely to be different for each font, but 0.2em is a
> reasonable starting-point).  There should then be (almost) no visible
> overhang at the left-hand side if it occurs at the start of a line in your
> prose text, _and_ you should get the normal interword space when the
> character occurs in the middle of a line.
>
>
>
> If this works, then you'll have to spend an hour or so doing it for all the
> relevant characters - it's always surprising just how many combinations
> there are to work through in polytonic Greek, as I discovered recently when
> I used Fontographer to do an amateurish (but functional!) conversion of my
> Porson Greek font to Unicode (I didn't want to use the GFS's version in
> spite of its Open Type features as it has the old upright capitals for
> Porson, whereas nowadays people expect the sloping capitals that were
> substitued in the twentieth century).    You would need to list all these
> \catcode redefenitions somewhere near the top of your file, before you start
> using the Greek.
>
>
>
> If you do want visible overhang at line-starts in poetry, say, you could do
> something clever with e.g. \newif\ifpoetry near the start of your file: then
> after \leavevmode in the above you would have \ifpoetry...... \else .....
> \fi:  the code after \else would be as above, and the code after \ifpoetry
> would be something like \llap{\hbox to 0.2em{\hfill
> \char"1FDE\hfill}}\char"0395  (Hope this works - I just thought of it!)
>
>
>
> One advantage of this is that when the font is improved (or you move over
> to another font which doesn't have this fault) you can just delete or
> comment out the \catcode definition section, or those parts of it which are
> no longer needed.  You could keep the list of \catcode definitions in a
> separate file which you might need for future use.  Whenever you do need it
> just give \input mycatcodes.tex (or whatever you've called it) in your file.
>
>
>
> Anyway, good luck!  (I use edmac all the time in plain XeTeX, but haven't
> investigated the LaTeX variety ledmac - I'm sure it's got more functionality
> and the results certainly look very nice).
>
>
>
>
>
>
>
> John
>
>
>
>
> ----- Original Message ----- From: "Pablo Rodríguez" <oinos at web.de>
> To: "Unicode-based TeX for Mac OS X and other platforms" <xetex at tug.org>
> Sent: Tuesday, October 06, 2009 8:07 AM
> Subject: Re: [XeTeX] [off-topic] proper OpenType tag for hanging diacritics
>
>
>
>  Karl Berry wrote:
>>
>>>    I'm afraid that this was the worst way of solving the issue, because
>>> the
>>>    effects when composing non-verse texts are obvious,
>>>
>>> How about reporting the problem to the authors of GFS Baskerville?
>>>
>>
>> Thanks, Karl, for you reply.
>>
>> Reporting the bug to the Greek Font Society is what I have in mind. But
>> I only wanted to know for sure whether optical bounds are the right
>> OpenType feature for that. From previous bug reports about their fonts,
>> I'm afraid that they don't know OpenType features very well.
>>
>> This is why I'm asking here about the proper OpenType feature.
>>
>>
>> Pablo
>>
>>
>
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