[Dev-luatex] Chars to glyphs. How to?

Taco Hoekwater taco at elvenkind.com
Wed Dec 5 15:06:43 CET 2007

Jonathan Sauer wrote:
> Hello,
>> [...]
>>> Questions:
>>> - Section 6 of the manual states that the key of the "characters"
>>>   table is the "internal code TeX knows this character by". How do
>>>   I determine this code? Is this simply the Unicode code point?

You do not have to determine that code, you are defining it by
feeding a specific 'characters' array back into the define_font

If your text has to be hyphenated and your hyphenation patterns are
true Unicode, then this had better be a Unicode code point.

Proper Unicode patterns is our recommended practise, but characters
array deviations are useful for symbolic fonts and for language+font
combinations that are hard to express in Unicode (patterns have to
be UTF-8 encoded, but there is no strict requirement for Unicode

> Now I'm back to confused. How is this my choice? Let's say I have an
> input file with character "ä". Would its "internal code TeX knows
> this character by" be Unicode's "LATIN CAPITAL LETTER A WITH DIAERESIS"
> (00C4)? If yes: So in order to add this character to an OT1-font, would
> I simply add it to the "characters" table with key hex C4 (and an
> appropriate command table)?

Yes, spot on.

> If I have a command table "char 23; char 42", will character number 42
> be typeset on top of character 23, or to the right? (yes, it does, as
> Taco answered) Could this be added to the manual, to make the behaviour
> of the "char" font command clearer? (since some other commands explicitely
> state of they move the output pointer)

I will be fixing the manual in the coming weeks. Your questions are
helping a lot in that they make it clear where further explanations
are needed.

Best wishes,

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