Adding OpenType features: Long GSUB Strings

[William]

Since the previous posts in this thread I have now purchased a licence for FontCreator 7 professional edition and I am updated to version 7.0.0 (build 368).

I have gained a little experience of making OpenType fonts and I have gained experience of using Serif PagePlus X5 (which is not the latest version) to try the fonts in an application. Much of it from the great fun of the thread of last Monday, 20 May 2013.

Open Type Question

I’m making a new font which has several very open characters (i, j, r) in particular. I’m working in Illustrator, and have made all the joined characters that I need (“ra”, “ir”, etc.). With Font Creator 7, are these considered ligatures (and if so, how do I define the new ligature characters), or new glyphs? I know I’ll have to learn the scripting, but I also read that some features of Open Type aren’t supported–I just don’t know what procedure I need to follow. This is my first try at Open Typ…

Earlier today I made a font Ligatures 004, which worked well on some ligatures but not on the longer extreme examples that I was trying for my research on communication through the language barrier.

So I made a copy of the project file as Ligatures 004a and added some extra lines so as to test what is happening.

Here is the font.
Ligatures 004.otf (21.4 KB)
Here is the OpenType code copied from the project file.

script latn {
  feature Ligatures;
}

feature Ligatures liga {
  lookup LigaLookup;
}

lookup LigaLookup {
  sub f f i -> ffi;
  sub f f l -> ffl;
  sub f f -> ff;
  sub f i -> fi;
  sub f l -> fl;
  sub longs t -> longst;
  sub s t -> st;
  sub c t -> c_t;
  sub f j -> f_j;
  sub d a -> d_a;
  sub colon colon 3 4 5 6 7 8 9 -> big9;
  sub colon colon 3 4 5 6 7 8 -> big8;
  sub colon colon 3 4 5 6 7 -> big7;
  sub colon colon 3 4 5 6 -> big6;
  sub colon colon 3 4 5 -> big5;
  sub colon colon 3 4 -> big4;
  sub colon colon 3 -> big3;
  sub colon colon 1 0 0 1 6 colon semicolon -> ls10016;
  sub colon colon 1 0 0 1 7 colon semicolon -> ls10017;
  sub colon colon -> lsmbob;
  sub colon semicolon -> lsmbcb;
}

I am wondering just how long a substitution the font will store and how long a substitution PagePlus X5 will accept.

I am still learning so I accept that I may not have got it all correct.

I managed to get the sub colon colon → lsmbob; substitution to work in PagePlus X5 and the sub colon colon 3 → big3; seems to have been recognized in some way as, although the big3 glyph did not become displayed on the screen in PagePlus X5 at first, when I was deleting something it suddenly became displayed and I do not know how!

I wonder if readers could test the font with whatever OpenType-aware applications they have please.

I appreciate that I am pushing the envelope on this, and I may need to just abandon the idea, but perhaps trying to understand what is happening might be of benefit to learning more about OpenType generally.

William Overington

22 May 2013