Number of possible characters in a substitution statement
Posted: Fri Apr 05, 2019 2:57 pm
You may have noticed the following thread.
viewtopic.php?f=10&t=7941
This question arises from that experiment but there is no need to read that thread in relation to this question, it is just the reason why I am asking.
In that font I used a liga glyph substitution statement as follows. (I use the term substitution statement - I do not know whether that is the correct term)
sub uniEFF8 uE0051 uE0032 uE0031 uE0038 uE0035 uE0034 uE0033 -> glyph218543;
That is a sequence of eight characters needed to result in the desired glyph being displayed.
It worked well both in FontCreator 8 in making a font and also in Affinity Publisher when using the font.
My question is as follows please.
Is there a limit within FontCreator as to how many characters can be in such a sequence? If so, what is it please? If so, is the limit imposed by High-Logic or by the OpenType specification.
The reason I ask is because there may be a need for at least three more tag characters, one of them the cancel tag, to be used straight away and maybe more in the longer term if the suggestion in the following document becomes implemented.
https://www.unicode.org/L2/L2019/19082-qid-emoji.pdf (It is over 6 Megabytes so I found it best to download to local storage rather than trying to read it online)
William Overington
Friday 5 April 2019
viewtopic.php?f=10&t=7941
This question arises from that experiment but there is no need to read that thread in relation to this question, it is just the reason why I am asking.
In that font I used a liga glyph substitution statement as follows. (I use the term substitution statement - I do not know whether that is the correct term)
sub uniEFF8 uE0051 uE0032 uE0031 uE0038 uE0035 uE0034 uE0033 -> glyph218543;
That is a sequence of eight characters needed to result in the desired glyph being displayed.
It worked well both in FontCreator 8 in making a font and also in Affinity Publisher when using the font.
My question is as follows please.
Is there a limit within FontCreator as to how many characters can be in such a sequence? If so, what is it please? If so, is the limit imposed by High-Logic or by the OpenType specification.
The reason I ask is because there may be a need for at least three more tag characters, one of them the cancel tag, to be used straight away and maybe more in the longer term if the suggestion in the following document becomes implemented.
https://www.unicode.org/L2/L2019/19082-qid-emoji.pdf (It is over 6 Megabytes so I found it best to download to local storage rather than trying to read it online)
William Overington
Friday 5 April 2019